GLOSSARY

A

AAMA American Architectural Manufacturers Association, a trade organization that develops standards for windows, doors, skylights, storefront, and curtain-wall systems.

Abutment joint A surface divider joint designed to allow free movement between new and existing construction or between differing materials.

AC See Articulation class.

ACC See Autoclaved aerated concrete.

Accelerating admixture An admixture that causes concrete or mortar to cure more rapidly.

Access flooring A raised finish floor surface consisting of small, individually removable panels beneath which wiring, ductwork, and other building services may be installed.

Access standard A set of regulations ensuring that buildings are accessible and usable by physically handicapped members of the population.

Acoustical ceiling A ceiling of fibrous tiles that are highly absorbent of sound energy.

ACQ See Alkaline copper quat.

Acrylic A transparent plastic material widely used in sheet form for glazing windows and skylights.

Active metal A metal relatively high on a galvanic series, tending to act as an anode in galvanic couples.

Actual dimension The true dimension of a material, as distinct from its nominal dimension.

ADA See Airtight drywall approach.

Admixture In a concrete or mortar, a substance other than cementitious material, water, and aggregates included in the mixture for the purpose of altering one or more properties of the mixed material, either in its plastic working state or after it has hardened.

Advanced framing techniques A wood light framing system that minimizes redundant framing members, reducing the amount of lumber required and increasing the thermal efficiency of the insulated frame.

Aerogel A silicon-based foam used to fill the interstitial space in insulating glazing units.

AESS See Architecturally exposed structural steel.

Aggregate Inert particles, such as sand, gravel, crushed stone, or expanded minerals, in a concrete, mortar, or plaster.

Air barrier A material that reduces air leakage through a building assembly.

Air barrier assembly An interconnected assemblage of materials that can effectively resist air pressure differentials acting across the boundary of a wall, roof, or floor assembly.

Air barrier system An interconnected collection of air barrier assemblies responsible for the overall air leakage performance of a completed building.

Air-entraining admixture An admixture that causes a controlled quantity of stable microscopic air bubbles to form in concrete or mortar during mixing, usually for the purposes of increasing workability and resistance to freeze-thaw conditions.

Air permeance A measure of a material's permeability to airflow. A low air permeance is a desirable characteristic of an air barrier material.

Air-supported structure A structure, usually long-span, with a fabric roof supported by an increase in air pressure inside the structure.

Airtight drywall approach (ADA) An air barrier system relying on gypsum board interior finish and the sealing of joints between framing members of a light frame building, serving to reduce the flow of air through the exterior walls and roof.

Air-to-air heat exchanger A device that exhausts air from a building while recovering much of the heat from the exhausted air and transferring it to the incoming air.

AISC American Institute of Steel Construction.

AISC Type I construction See Fully restrained moment connection.

AISC Type II construction See Simple connection.

AISC Type III construction See Partially restrained moment connection.

Albedo See Solar reflectance.

Alkaline copper quat (ACQ) A chemical used to preserve wood against attack by decay and insects.

Alloy A substance composed of two or more metals or of a metal and a nonmetallic constituent.

Aluminum A silver-colored, nonferrous metal that naturally forms a self-protecting oxide layer.

Anchorage The device that fastens the end of a posttensioning tendon to the end of a concrete slab or beam.

Anchor bolt A bolt embedded in concrete for the purpose of fastening a building frame to a concrete or masonry foundation.

Angle A structural section of steel or aluminum whose profile resembles the letter L.

Angle of repose The steepest angle at which an excavation may be sloped so that the soil will not slide back into the hole.

Annealed Cooled under controlled conditions to minimize internal stresses.

Anode The metal in a galvanic couple that experiences accelerated corrosion.

Anodizing An electrolytic process that forms a permanent protective oxide coating on aluminum, with or without added color.

ANSI American National Standards Institute, an organization that fosters the establishment of voluntary industrial standards.

Anticlastic Saddle-shaped or having curvature in two opposing directions.

APP See Atactic polypropylene.

Appearance grading The grading of wood for its appearance properties, as distinct from its structural properties; not to be confused with visual grading

Apron The finish piece that covers the joint between a window stool and the wall finish below.

Arch A structural device that supports a vertical load by translating it into axial inclined forces at its supports.

Architectural concrete Concrete intended as a finish surface and produced to a higher-quality standard.

Architectural sheet metal roofing A roof covering made up of sheets of metal in a traditional shop- or site-fabricated pattern such as standing seam, flat seam, or batten seam.

Architecturally exposed structural steel (AESS) Structural steel intended to be left exposed in the finished building and fabricated and installed to a higher-quality standard.

Architectural Woodwork Institute (AWI) A trade organization that develops standards for custom millwork.

Arc welding A process of joining two pieces of metal by melting them together at their interface with a continuous electric spark and adding a controlled additional amount of molten metal from a metallic electrode.

Area divider A curb used to partition a large roof membrane into smaller areas to allow for expansion and contraction in the deck and membrane.

Articulation class (AC) A measure of a finish ceiling's absorption and reflection of sound, particularly with regard to speech clarity in an open office environment.

Ash dump A door in the underfire of a fireplace that permits ashes from the fire to be swept into a chamber beneath, from which they may be removed at a later time.

Ashlar Squared stonework.

Asphalt A tarry brown or black mixture of hydrocarbons; one type of bitumen.

Asphalt roll roofing A continuous sheet of the same roofing material used in asphalt shingles. See Asphalt shingle.

Asphalt-saturated felt A water-resistive sheet material, available in several different thicknesses, usually consisting of matted cellulose fibers that have been impregnated with asphalt; used to provide a protective layer in an exterior wall or roof assembly; also called building felt.

Asphalt shingle A roofing unit composed of a heavy organic or inorganic felt saturated with asphalt and faced with mineral granules.

ASTM American Society for Testing and Materials, an organization that promulgates standards for testing, materials, and methods of building construction.

Atactic polypropylene (APP) An amorphous form of polypropylene used as a modifier in modified bitumen roofing.

Auger A helical tool for creating cylindrical holes.

Autoclaved aerated concrete (AAC) Concrete formulated so as to contain a large percentage of gas bubbles as a result of a chemical reaction that takes place in an atmosphere of steam.

AWI See Architectural Woodwork Institute.

Awning window A window that pivots on a horizontal axis at the top edge of the sash and projects toward the outdoors.

Axial In a direction parallel to the long axis of a structural member.

B

Backer board A fiber-reinforced cement board or glass-mat-faced gypsum board used as a base for thin-set tile applications.

Backer rod A flexible, compressible strip of plastic foam inserted into a joint to limit the depth to which sealant can penetrate.

Backfill Earth or earthen material used to fill the excavation around a foundation; the act of filling around a foundation.

Backup, backup wall A vertical plane of masonry, concrete, or wood framing used to support a thin facing such as a single wythe of brickwork.

Backup bar A small rectangular strip of steel applied beneath a joint to provide a solid base for beginning a weld between two steel structural members.

Ballast A heavy material installed over a roof membrane to prevent wind uplift and shield the membrane from sunlight.

Balloon frame A wooden building frame composed of closely spaced members nominally 2 inches (51 mm) thick, in which the wall members are single pieces that run from the sill to the top plates at the eave.

Baluster A small vertical member that serves to fill the opening between a handrail and a stair or floor.

Band joist A wooden joist running perpendicular to the primary direction of the joists in a floor and closing off the floor platform at the outside face of the building.

Bar A small rolled steel shape, usually round or rectangular in cross section; a rolled steel shape used for reinforcing concrete.

Barrel shell A scalloped roof structure of reinforced concrete that spans in one direction as a barrel vault and in the other as a folded plate.

Barrel vault A segment of a cylindrical surface that spans as an arch.

Barrier wall An exterior wall of a building whose watertightness depends on its freedom from passages through the wall.

Basalt A very dense and durable igneous rock, usually dark gray in color; classified by ASTM C119 in the Granite group.

Baseboard A strip of finish material placed at the junction of a floor and a wall to create a neat intersection and to protect the wall against damage from feet, furniture, and floor-cleaning equipment.

Base-coat plaster One or more preparatory plaster coats that provide a flat, solid surface suitable for the application of the final finish coat plaster. See also Scratch coat and Brown coat.

Base flashing The flashing at the edges of a low-slope roof membrane that turns up against the adjacent face of a parapet or wall, and frequently overlapped by a counterflashing.

Base isolator A device at foundation level that diminishes the transmission of seismic motions to a building.

Baseplate A steel plate inserted between a column and a foundation to spread the concentrated load of the column across a larger area of the foundation.

Basic oxygen process A steel-making process in which a stream of pure oxygen is introduced into a batch of molten iron so as to remove excess carbon and other impurities.

Batten A strip of wood or metal used to cover the crack between two adjoining boards or panels.

Batten-seam A seam in a sheet metal roof that encloses a wood batten.

Batter board Boards mounted on stakes outside the excavation area of a building, used to preserve locations for string lines marking the corners of the building foundation.

Bay A rectangular area of a building defined by four adjacent columns; a portion of a building that projects from a facade.

Bead A narrow line of weld metal or sealant; a strip of metal or wood used to hold a sheet of glass in place; a narrow, convex molding profile, a metal edge or corner accessory for plaster.

Beam A straight structural member that acts primarily to resist nonaxial loads.

Beam blank See Bloom.

Bearing A point at which one building element rests upon another.

Bearing block A piece of wood fastened to a column to provide support for a beam or girder.

Bearing pad A block of plastic or synthetic rubber used to cushion the point at which one precast concrete element rests upon another.

Bearing wall A wall that supports floors or roofs.

Bed See Casting bed.

Bed joint The horizontal layer of mortar beneath a masonry unit.

Bedrock A solid stratum of rock.

Bending moment The combination of tension and compression forces that cause a beam or other structural member to bend. See also Moment.

Bending stress A compressive or tensile stress resulting from the application of a nonaxial force to a structural member.

Bent A plane of framing consisting of beams and columns joined together, often with rigid joints.

Bentonite clay An absorptive colloidal clay that swells to several times its dry volume when saturated with water; the primary ingredient in bentonite waterproofing.

Bessemer process An early method of steel manufacturing in which air was blown into a vessel of molten iron to burn out impurities.

Bevel An end or edge that is cut at an angle other than a right angle.

Bevel siding Wood cladding boards that taper in cross section.

Billet A large cylinder or rectangular solid of material.

BIM See Building information modeling.

Birdsmouth cut An angled notch cut into a rafter to allow the rafter to seat securely on the top plate of a wall.

Bite The depth to which the edge of a piece of glass is held by its frame.

Bitumen A tarry mixture of hydrocarbons, such as asphalt or coal tar.

Bituminous roof membrane A low-slope roof membrane made from bituminous materials, either a built-up roof membrane or a modified bitumen roof membrane.

Blast furnace slag A hydraulic cementitious material formed as a byproduct of iron manufacture, used in mortar and concrete mixtures; also called slag cement.

Blast-resistant glazing Window, storefront, or curtainwall systems designed for resistance to the force of explosive blasts.

Bleed water In freshly placed concrete, water that rises to the top surface of the concrete as the solid cement and aggregate particles settle.

Blended hydraulic cement Hydraulic cement made from a mixture of cementitious materials such as portland cement, other hydraulic cements, and pozzolans for the purpose of altering one or more properties of the cement or reducing the energy required in the cement manufacturing process.

Blind nailing Attaching boards to a frame, sheathing, or subflooring with toe nails driven through the edge of each piece so as to be completely concealed by the adjoining piece.

Blind-side waterproofing An impervious layer or coating on the outside of a foundation wall that, for reasons of inaccessibility, was installed before the wall was constructed.

Blocking Pieces of wood inserted tightly between joists, studs, or rafters in a building frame to stabilize the structure, inhibit the passage of fire, provide a nailing surface for finish materials, or retain insulation.

Bloom A rectangular solid of steel formed from an ingot as an intermediate step in creating rolled steel structural shapes.

Blooming mill A set of rollers used to transform an ingot into a bloom.

Bluestone A sandstone that is gray to blue-gray in color and splits readily into thin slabs; classified by ASTM C119 in the Quartz-Based Stone group.

Board foot A unit of lumber volume, a rectangular solid nominally 12 square inches in cross-sectional area and 1 foot long.

Board siding Wood cladding made up of boards, as differentiated from shingles or manufactured wood panels.

Bolster A long chair used to support reinforcing bars in a concrete slab.

Bolt A fastener consisting of a cylindrical metal body with a head at one end and a helical thread at the other, intended to be inserted through holes in adjoining pieces of material and closed with a threaded nut.

Bond In masonry, the adhesive force between mortar and masonry units, or the pattern in which masonry units are laid to tie two or more wythes together into a structural unit. In reinforced concrete, the adhesion between the surface of a reinforcing bar and the surrounding concrete.

Bond breaker A strip of material to which sealant does not adhere.

Bonded posttensioning A system of prestressing in which the tendons are grouted after stressing so as to bond them to the surrounding concrete.

Bonded terrazzo Terrazzo flooring whose underbed is poured directly upon the structural floor.

Bottom bar A reinforcing bar that lies close to the bottom of a beam or slab.

Bottom plate See Sole plate.

Bound water In wood, the water held within the cellulose of the cell walls. See also Free water.

Box beam A bending member of metal or plywood whose cross section resembles a closed rectangular box.

Box girder A major spanning member of concrete or steel whose cross section is a hollow rectangle or trapezoid.

Box nail A nail with a more slender shank than a common nail, used for fastening framing members in wood light frame construction.

Braced frame A structural building frame strengthened against lateral forces with diagonal members.

Bracing Diagonal members, either temporary or permanent, installed to stabilize a structure against lateral loads.

Brad A small finish nail.

Brake A machine used to form lengths of sheet metal into bent shapes.

Brazing A process that uses molten, nonferrous metal to join two pieces of metal. The brazing metal is melted at a temperature below that of the metals being joined, so that, unlike in welding, the joined metals remain in a solid state throughout the process.

Breather mat A wiry plastic matting placed within a roof or wall assembly to create a space for drainage and ventilation.

Bridging Bracing or blocking installed between steel or wood joists at midspan to stabilize them against buckling and, in some cases, to permit adjacent joists to share loads.

British thermal unit (BTU) The quantity of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.

Broom finish A skid-resistant texture imparted to an uncured concrete surface by dragging a stiff-bristled broom across it.

Brown coat The second of two basecoat plaster applications in a three-coat plaster.

Brownstone A brownish or reddish sandstone; classified by ASTM C119 in the Quartz-Based Stone group.

BTU See British thermal unit.

Buckling Structure failure by gross lateral deflection of a slender element under compressive stress, such as the sideward buckling of a long, slender column or the upper edge of a long, thin floor joist.

Building brick Brick used for concealed masonry work where appearance is not a concern.

Building code A set of regulations intended to ensure a minimum standard of health and safety in buildings.

Building enclosure The parts of the building, principally its walls, roofs, and fenestration, that separate the interior of the building from the exterior, and that must effectively control the flow of heat, air, and moisture; also called the thermal envelope or the building envelope.

Building envelope See Building enclosure.

Building felt See Asphalt-saturated felt.

Building information modeling (BIM) The computerized three-dimensional modeling of building systems, with the linking of model components to a database of properties and relationships.

Building paper A water-resistive, asphalt-saturated paper used similarly to asphalt-saturated felt, to provide a protective layer in an exterior wall assembly.

Building separation joint A plane along which a building is divided into separate structures that may move independently of one another.

Built-up roof (BUR) A multi-ply roof membrane, made from layers of asphalt-saturated felt or other fabric, bonded together with bitumen.

Bull float A long-handled tool used for the initial floating of a freshly poured concrete slab. See also Darby.

Buoyant uplift The force of water or liqufied soil that tends to raise a building foundation out of the ground.

BUR See Built-up roof.

Butt The thicker end, such as the lower edge of a wood shingle or the lower end of a tree trunk; a joint between square-edged pieces; a weld between square-edged pieces of metal that lie in the same plane; a type of door hinge that attaches to the edge of the door.

Butt-joint glazing A type of glass installation in which the vertical joints between lights of glass do not meet at a mullion, but are made weathertight with a sealant.

Button head A smooth, convex bolt head with no provision for engaging a wrench.

Buttress A structural device of masonry or concrete that resists the diagonal forces from an arch or vault.

Butyl rubber A synthetic rubber compound.

C

CA See Copper boron azole.

CAC See Ceiling Attenuation Class.

CAD See Computer-aided design.

Caisson A cylindrical sitecast concrete foundation unit that penetrates through unsatisfactory soil to rest upon an underlying stratum of rock or satisfactory soil; an enclosure that permits excavation work to be carried out underwater. Also called a drilled pier.

Calcined gypsum. Gypsum which has been ground to a fine powder and heated to drive off most of its water of hydration; used in the manufacture of gypsum board and as the principal ingredient in gypsum plasters; a nonhydraulic cementitious material; also called plaster of Paris.

Calcining The driving off of the water of hydration from gypsum by the application of heat.

Camber A slight, intentional initial curvature in a beam or slab.

Cambium The thin layer beneath the bark of a tree that manufactures cells of wood and bark.

Cantilever A beam, truss, or slab that extends beyond its last point of support.

Cant strip A strip of material with a sloping face used to ease the transition from a horizontal to a vertical surface at the edge of a membrane roof.

Capillary action The pulling of water through a small orifice or fibrous material by the adhesive force between the water and the material.

Capillary break A slot or groove intended to create an opening too large to be bridged by a drop of water and, thereby, to eliminate the passage of water by capillary action; the coarse aggregate layer under a concrete slab on grade which reduces the migration of water from the ground below into the concrete slab above.

Carbide-tipped tools Drill bits, saws, and other tools with cutting edges made of an extremely hard alloy.

Carbonation The process by which lime mortar reacts with atmospheric carbon dioxide to cure.

Carbon fiber reinforcing In precast concrete, an open grid fabric of carbon fibers bonded with epoxy resin, used as a substitute for welded-wire reinforcing.

Carbon steel Low-carbon or mild steel.

Carpenter One who makes things of wood.

Casement window A window that pivots on an axis at or near a vertical edge of the sash.

Casing The wood finish pieces surrounding the frame of a window or door; a cylindrical steel tube used to line a drilled or driven hole in foundation work.

Castellated beam A steel wide-flange section whose web has been cut along a zigzag path and reassembled by welding in such a way as to create a deeper section.

Casting Pouring a liquid material or slurry into a mold whose form it will take as it solidifies.

Casting bed A permanent, fixed form in which precast concrete elements are produced.

Cast in place Concrete that is poured in its final location; sitecast.

Cast iron Iron with too high a carbon content to be classified as steel.

Cathode The metal in a galvanic couple that experiences a decreased rate of corrosion.

Caulk A low-range sealant.

Cavity drainage material A material placed in the air space of a cavity wall to catch mortar droppings and prevent clogging of weep holes at the bottom of the cavity.

Cavity wall A masonry wall that includes a continuous airspace between its outermost wythe and the remainder of the wall.

CBA See Copper boron azole.

CCA See Chromated copper arsenate.

Cee A metal framing member whose cross-sectional shape resembles the letter C.

Ceiling Attenuation Class (CAC) An index of the ability of a ceiling construction to obstruct the passage of sound between rooms through the plenum.

Ceiling joist See Joist.

Cellular decking Panels made of steel sheets corrugated and welded together in such a way that hollow longitudinal cells are created within the panels.

Cellular raceway A rectangular tube cast into a concrete floor slab for the purpose of housing electrical and communications wiring.

Cellulose A complex polymeric carbohydrate of which the structural fibers in wood are composed.

Celsius A temperature scale on which the freezing point of water is established as 0 and the boiling point as 100 degrees.

Cement Generally, any substance used to adhere material together. In concrete, masonry, and plastering work, any of a number of inorganic materials that have cementing properties when combined with the water. See also Cementitious materials.

Cementitious materials In concrete, masonry, and plastering, inorganic materials that, when mixed with water, produce hardened products with adhesive and cohesive (cementing) properties; frequently used to refer exclusively to hydraulic cements (such as portland cement), to the exclusion of nonhydraulic (lime and gypsum) cements.

Cement-lime mortar Mortar made from portland cement, hydrated lime, aggregate, and water, the most traditional formulation of modern masonry mortars. See also Masonry cement, Mortar cement.

Centering Temporary formwork for an arch, dome, or vault.

Centering shims Small blocks of synthetic rubber or plastic used to hold a sheet of glass in the center of its frame.

Ceramic tile Small, flat, thin clay tiles intended for use as wall and floor facings.

Chair A device used to support reinforcing bars.

Chamfer A flattening of a longitudinal edge of a solid member on a plane that lies at an angle of 45 degrees to the adjoining planes.

Channel A steel or aluminum section shaped like a rectangular box with one side missing.

Chemically strengthened glass Glass strengthened by immersion in a molten salt bath, causing an ion exchange at the surfaces of the glass that creates a prestress in much the same manner as heat-treated glass.

Chlorinated polyethylene (CPE) A plastic material used in roof membranes.

Chlorosulfonated polyethylene (CSPE) A plastic material used in roof membranes.

Chord A top or bottom member of a truss.

Chromated copper arsenate (CCA) A chemical used to protect wood against attack by decay and insects. Due to toxicity concerns, this chemical has been phased out of most treated wood used in residential and commercial buliding construction.

Chromogenic glass Glass that can change its optical properties, such as thermochromic, photochromic, or electrochromic glass.

C-H stud A steel wall framing member whose profile resembles a combination of the letters C and H, used to support gypsum panels in shaft walls.

Chuck A device for holding a steel wire, rod, or cable securely in place by means of steel wedges in a tapering cylinder.

Churn drill A steel tool used with an up-and-down motion to cut through rock at the bottom of a steel pipe caisson.

Cladding A material used to cover the exterior of a building.

Clamp A tool for holding two pieces of material together temporarily; unfired bricks piled in such a way that they can be fired without using a kiln.

Class A, B, C roofing Roof covering materials classified according to their resistance to fire when tested in accordance with ASTM E108. Class A is the most resist tant, and Class C is the least.

Clay A fine-grained soil with plate-shaped particles less than 0.0002 inch (0.005 mm) in size, which properties are significantly influenced by the structural arrangements of the particles and the electrostatic forces acting between them.

Cleanout hole An opening at the base of a masonry wall through which mortar droppings and other debris can be removed prior to grouting the interior cavity of the wall.

Clear dimension, clear opening The dimension between opposing inside faces of an opening.

Cleavage membrane A resilient sheet placed underneath a finish tile assembly to prevent movement stresses in the underlying substrate from telegraphing into the finish assembly.

Climbing crane A heavy-duty lifting machine that raises itself as the building rises.

Clinker A fused, pebblelike mass that is an intermediate product of cement manufacture; a brick that is overburned.

Closer The last masonry unit laid in a course; a partial masonry unit used at the corner of a header course to adjust the joint spacing; a mechanical device for regulating the closing action of a door.

CLSM See Controlled low-strength material.

CMU See Concrete masonry unit.

Coarse aggregate Gravel or crushed stone in a concrete mix.

Coarse-grained soil Soil with particles ranging in size from roughly 0.003 to 3 inches (0.075–75 mm); sands and gravels.

Code See Building code.

Cohesionless soil See Frictional soil.

Cohesive soil A soil such as clay whose particles are able to adhere to one another by means of cohesive and adhesive forces.

Cold-formed steel See Cold-worked steel.

Cold-rolled steel Steel rolled to its final form at a temperature at which it is no longer plastic.

Cold-worked steel Steel formed at a temperature at which it is no longer plastic, as by rolling or forging at room temperature.

Collar joint The vertical mortar joint between wythes of masonry.

Collar tie A piece of wood nailed across two opposing rafters near the ridge to resist wind uplift.

Collated nails Nails glued together in a strip for insertion into a nail gun.

Column An upright structural member acting primarily in compression.

Column bar See Vertical bar.

Column cage An assembly of vertical reinforcing bars and ties for a concrete column.

Column-cover-and-spandrel system A system of cladding in which panels of material cover the columns and spandrels, with horizontal strips of windows filling the remaining portion of the wall.

Column spiral A continuous coil of steel reinforcing used to tie a concrete column.

Column tie A single loop of steel bar, usually bent into a rectangular configuration, used to tie a concrete column.

Combination door A door with interchangeable inserts of glass and insect screening, usually used as a second, exterior door and mounted in the same opening with a conventional door.

Combination window A sash that holds both insect screening and a retractable sheet of glass, mounted in the same frame with a window and used to increase its thermal resistance.

Commercial wrap A synthetic sheet material, heavier than housewrap, with water-resistive and air-resistive properties used to provide a protective layer in an exterior wall assembly.

Common bolt An ordinary carbon steel bolt.

Common bond Brickwork laid with five courses of stretchers followed by one course of headers.

Common nail A standard-sized nail used for the fastening of framing members in wood light frame construction.

Common rafter A roof rafter that runs parallel to the main slope of the roof. See also Hip rafter.

Composite A material or assembly made up of two or more materials bonded together to act as a single structural unit.

Composite column An upright structural member, acting primarily in compression, that is composed of concrete and a steel structural shape, usually a wide flange or a tube.

Composite construction Any element in which concrete and steel, other than reinforcing bars, work as a single structural unit.

Composite metal decking Corrugated steel decking manufactured in such a way that it bonds securely to the concrete floor fill to form a reinforced concrete deck.

Composite wall A masonry wall that incorporates two or more different types of masonry units, such as clay bricks and concrete blocks.

Composition shingle See Asphalt shingle.

Compression A squeezing force.

Compression gasket A synthetic rubber strip that seals around a sheet of glass or a wall panel by being squeezed tightly against it.

Compressive strength The ability of a structural material to withstand squeezing forces.

Computer-aided design (CAD) The digital two-dimensional representation of building systems.

Concave joint A mortar joint tooled into a curved, indented profile.

Concealed flashing See Internal flashing.

Concealed grid A suspended ceiling framework that is completely hidden by the tiles or panels it supports.

Concrete A structural material produced by mixing predetermined amounts of cement, aggregates, and water and allowing this mixture to cure under controlled conditions.

Concrete block A concrete masonry unit, usually hollow, that is larger than a brick.

Concrete masonry unit (CMU) A block of hardened concrete, with or without hollow cores, designed to be laid in the same manner as a brick or stone; a concrete block.

Condensate Water formed as a result of condensation.

Condensation The process of changing from a gaseous to a liquid state, especially as applied to water.

Conduit A steel or plastic tube through which electrical wiring is run.

Consolidate In freshly poured concrete, eliminate trapped air and cause the concrete to fill completely around the reinforcing bars and into all the corners of the formwork, usually by vibrating the concrete.

Construction documents The graphic construction drawings and written specifications to which a building is constructed.

Construction Drawings The graphic instructions from an architect or an engineer concerning the construction of a building.

Construction manager An entity that assists the owner in the procurement of construction services.

Construction Type In the International Building Code, any of five major systems of building construction that are differentiated by their relative resistance to fire.

Continuous ridge vent See Ridge vent.

Contraction joint See Control joint.

Contractor A person or organization that undertakes a legal obligation to do construction work.

Control joint An intentional, linear discontinuity in a structure or component designed to form a plane of weakness where cracking can occur in response to various forces so as to minimize or eliminate cracking elsewhere in the structure. Also called a contraction joint.

Controlled low-strength material (CLSM) A concrete that is purposely formulated to have a very low but known strength, used primarily as a backfill material.

Convector A heat exchange device that uses the heat in steam, hot water, or an electric resistance element to warm the air in a room; often called, inaccurately, a radiator.

Cool color A coating applied to a roofing material that is nonwhite, yet reflects a relatively high percentage of the sun's thermal energy.

Cool roof A roof covering that reflects a substantial portion of the sun's thermal energy.

Cope The removal of a flange at the end of a steel beam in order to facilitate connection to another member.

Coped connection A joint in which the end of one member is cut to match the profile of the other member.

Coping A protective cap on the top of a masonry wall.

Coping saw A handsaw with a thin, narrow blade, used for cutting detailed shapes in the ends of wood moldings and trim.

Copolymer A large molecule composed of repeating patterns of two or more chemical units.

Copper A soft, nonferrous metal, orange-red in color, that oxidizes to a color ranging from blue-green to black.

Copper boron azole (CBA, CA) A chemical used to preserve wood against attack by decay and insects.

Corbel A spanning device in which masonry units in successive courses are cantilevered slightly over one another; a projecting bracket of masonry or concrete.

Coreboard A thick gypsum panel used primarily in shaft walls.

Corner bead A metal or plastic strip used to form a neat, durable edge at an outside corner of two walls of plaster or gypsum board.

Cornice The exterior detail at the meeting of a wall and a roof overhang; a decorative molding at the intersection of a wall and a ceiling.

Corrosion Oxidation, such as rust.

Corrosion inhibitor A concrete admixture intended to prevent oxidation of reinforcing bars.

Corrugated Formed into a fluted or ribbed profile.

Counterflashing A flashing turned down from above to overlap another flashing turned up from below so as to shed water.

Course A horizontal layer of masonry units one unit high; a horizontal line of shingles or siding.

Coursed In masonry, laid in courses with straight bed joints.

Cove base A flexible strip of plastic or synthetic rubber used to finish the junction between resilient flooring and a wall.

Cover In concrete, a specified thickness of concrete surrounding steel reinforcing bars to provide full embedment for the bars and protect them against fire and corrosion.

CPE See Chlorinated polyethylene.

Crawlspace A space that is not tall enough to stand in, located beneath the bottom of a building.

Creep A permanent inelastic deformation in a material due to changes in the material caused by the prolonged application of a structural stress, common in wood and concrete.

Cripple stud A wood wall framing member that is shorter than full-length studs because it is interrupted by a header or sill.

Critical path The sequence of tasks that determines the least amount of time in which a construction project can be completed.

Cross-grain wood Wood incorporated into a structure in such a way that the direction of its grain is perpendicular to the direction of the principal loads on the structure.

Crosslot bracing Horizontal compression members running from one side of an excavation to the other, used to support sheeting.

Crown glass Glass sheet formed by spinning an opened hollow globe of heated glass.

Cruck A framing member cut from a bent tree so as to form one-half of a rigid frame.

CSPE See Chlorosulfonated polyethylene.

Cup A curl in the cross section of a board or timber caused by unequal shrinkage or expansion between one side of the board and the other.

Curing The hardening of concrete, plaster, gunnable sealant, or other wet materials. Curing can occur through evaporation of water or a solvent, hydration, polymerization, or chemical reactions of various types, depending on the formulation of the material.

Curing compound A liquid that, when sprayed on the surface of newly placed concrete, forms a water-resistant layer to prevent premature dehydration of the concrete.

Curtain wall An exterior building wall that is supported entirely by the frame of the building, rather than being self-supporting or loadbearing.

Cylinder glass Glass sheet produced by blowing a large, elongated glass cylinder, cutting off its ends, slitting it lengthwise, and opening it into a flat rectangle.

D

d See Penny.

Damper A flap to control or obstruct the flow of gases; specifically, a metal control flap in the throat of a fireplace or in an air duct.

Dampproofing A coating intended to resist the passage of water, commonly applied to the outside face of basement walls or to the inner face of a cavity in a masonry cavity wall.

Dap A notch at the end of a piece of material.

Darby A stiff straightedge of wood or metal used to level the surface of wet plaster or concrete.

Daylighting Illuminating the interior of a building by natural means.

Dead load Permanent loads on a building, including the weight of the building itself and any permanently attached equipment.

Deadman A large and/or heavy object buried in the ground as an anchor.

Decking A material used to span across beams or joists to create a floor or roof surface.

Deep foundation A building foundation that extends through upper strata of incompetent soil to reach deeper strata with greater bearing capacity.

Deformation A change in the shape of a structure or structural element caused by a load or force acting on the structure.

Deformed reinforcing bar Steel reinforcing bars with surface ribs for better bonding to concrete.

Depressed strand A pretensioning tendon that is pulled to the bottom of the beam at the center of the span to follow more closely the path of tensile forces in the member.

Derrick Any of a number of devices for hoisting building materials on the end of a rope or cable.

Design/bid/build project delivery A method of providing design and construction services in which the design and construction phases of the project are provided by different entities, usually used in combination with sequential construction.

Design/build project delivery A method of providing design and construction services in which the design and construction phases of the project are provided by a single entity, frequently used in combination with fast track construction.

Dew point The temperature at which water will begin to condense from a mass of air with a given moisture content.

Dewatering The extraction of water from an excavation or its surrounding soil.

Diagonal bracing See Bracing.

Diamond saw A tool with a moving chain, belt, wire, straight blade, or circular blade whose cutting action is carried out by diamonds.

Diaphragm action A bracing action that derives from the stiffness of a thin plane of material when it is loaded in a direction parallel to the plane. Diaphragms in buildings are typically floor, wall, or roof surfaces of plywood, reinforced masonry, steel decking, or reinforced concrete.

Die An industrial tool for giving identical form to repeatedly produced or continuously generated units, such as a shaped orifice for giving form to a column of clay, a steel wire, or an aluminum extrusion; a shaped punch for making cutouts of sheet metal or paper; or a mold for casting plastic or metal.

Die-cut Manufactured by punching from a sheet material.

Differential settlement Subsidence of the various foundation elements of a building at differing rates.

Diffuser A louver shaped so as to distribute air about a room.

Dimension lumber Lengths of wood, rectangular in cross section, sawed directly from the log.

Dimension stone Building stone cut to a rectangular shape.

Direct tension indicator washer See Load indicator washer.

Distribution rib A transverse beam at the midspan of a one-way concrete joist structure, used to allow the joists to share concentrated loads.

Divider strip A strip of metal or plastic embedded in terrazzo to form control joints and decorative patterns.

Dome An arch rotated about its vertical axis to produce a structure shaped like an inverted bowl; a form used to make one of the cavities in a concrete waffle slab.

Dormer A structure protruding through the plane of a sloping roof, usually containing a window and having its own smaller roof.

Double glazing Two parallel sheets of glass with an airspace between.

Double-hung window A window with two overlapping sashes that slide vertically in tracks.

Double shear Acting to resist shear forces at two locations, such as a bolt that passes through a steel supporting angle, a beam web, and another supporting angle.

Double-skin facade An exterior wall system consisting of two separate glass skins separated by an interstitial space; also called dual-wall facade or double-skin wall.

Double-skin wall See Double-skin facade.

Double-strength glass Glass that is approximately ⅛ inch (3 mm) thick.

Double tee A precast concrete slab element that resembles the letters TT in cross section.

Dovetail slot anchor A system for fastening to a concrete structure that uses metal tabs inserted into a slot that is small at the face of the concrete and larger behind.

Dowel A short cylindrical rod of wood or steel; a steel reinforcing bar that projects from a foundation to tie it to a column or wall, or from one section of a concrete slab or wall to another.

Downspout A vertical pipe for conducting water from a roof to a lower level, also called a leader.

Drainage Removal of water.

Drainage backfill Crushed stone or gravel backfill materials with good drainage characteristics, placed around a foundation to facilitate drainage.

Draped tendon A posttensioning strand that is placed along a curving profile that approximates the path of the tensile forces in a beam.

Drawing Shaping a material by pulling it through an orifice, as in the drawing of steel wire or the drawing of a sheet of glass.

Drawings See Construction Drawings.

Drawn glass Glass sheet pulled directly from a container of molten glass.

Drift Lateral deflection of a building caused by wind or earthquake loads.

Drift pin A tapered steel rod used to align bolt holes in steel connections during erection.

Drilled pier See Caisson.

Drip A discontinuity formed into the underside of a window sill or wall component to force adhering drops of water to fall free of the face of the building rather than to move farther toward the interior.

Dropchute A flexible hoselike tube for placing concrete; used to break the fall of the concrete and prevent segregation.

Drop panel A thickening of a two-way concrete structure at the head of a column.

Drying shrinkage Shrinkage of concrete, mortar, or plaster, that occurs as excess water evaporates from the material.

Dry-pack grout A low-slump cementitious mixture tamped into the space in a connection between precast concrete members.

Dry-press process A method of molding slightly damp clays and shales into bricks by forcing them into molds under high pressure.

Dry-set mortar A tile setting mortar formulated with portland cement, sand, and water retention compounds, used in thin-set tile applications.

“Dry” systems Systems of construction that use little or no water during construction, as differentiated from systems such as masonry, plastering, and ceramic tile work.

Drywall See Gypsum board.

Dry well An underground pit filled with broken stone or other porous material from which rainwater from a roof drainage system can seep into the surrounding soil.

Dual-wall facade See Double-skin facade.

Duct A hollow conduit, commonly of sheet metal, through which air can be circulated; a tube used to establish the position of a posttensioning tendon in a concrete structure.

DWV Pipe Drain–waste–vent pipe; the part of the plumbing system of a building that removes liquid wastes and conducts them to the sewer or sewage disposal system.

E

Earlywood See Springwood.

Earth material Rock or soil.

Eave The horizontal edge at the low side of a sloping roof.

Eco-roof See Green roof.

Edge bead A strip of metal or plastic used to make a neat, durable edge where plaster or gypsum board abuts another material.

Edge-grain lumber See Vertical gain lumber.

Edge spacer The material used to separate lights of glass in an insulating glass unit, also called a spline.

Efflorescence A powdery deposit on the face of a structure of masonry or concrete, caused by the leaching of chemical salts by water migrating from within the structure to the surface.

EIFS See Exterior insulation and finish system.

Elastic Able to return to its original size and shape after removal of stress.

Elastomer A rubber or synthetic rubber.

Elastomeric Rubberlike. In low-slope roofing, a thermosetting membrane material.

Electrochromic glass Glass that changes its optical properties in response to the application of electric current.

Electrode A consumable steel wire or rod used to maintain an arc and furnish additional weld metal in electric arc welding.

Electrogalvanizing A method of galvanizing, in which an electric current is used to deposit zinc from a liquid bath onto steel.

Elevation A drawing that views a building from any of its sides; a vertical height above a reference point such as sea level.

Elongation Stretching under load; growing longer because of temperature expansion.

Embodied energy The total life cycle energy expended in extraction of raw materials, processing, fabrication, and transportation of a material or product to its point of use in a building; in some calculations, may also include energy required to dispose of or recycle the material.

EMC See Equilibrium moisture content.

Enamel A glossy or semigloss paint.

End dam The turned-up end of a flashing that prevents water from running out of the end; a block inserted into the space within a horizontal aluminum mullion for the same purpose.

End nail A nail driven through the side of one piece of lumber and into the end of another.

Engineered fill Earth compacted into place in such a way that it has predictable physical properties, based on laboratory tests and specified, supervised installation procedures.

Engineered lumber See Structural composite lumber.

English bond Brickwork laid with alternating courses, each consisting entirely of headers or stretchers.

EPDM Ethylene propylene diene monomer, a synthetic rubber thermosetting material used in low-slope roofing membranes.

Equilibrium moisture content (EMC) The moisture content at which wood stabilizes after a period of time in its destination environment.

Erector The subcontractor who raises, connects, and plumbs up a building frame from fabricated steel or precast concrete components.

Ethylene propylene diene monomer See EPDM.

Expanded metal lath A thin sheet of metal that has been slit and stretched to transform it into a mesh, used as a base for the installation of plaster.

Expanded shale aggregate A structural lightweight aggregate made from ground shale particles that have been heated to the point that moisture within the particles vaporizes, causing the particles to expand.

Expansion joint A surface divider joint that provides space for the surface to expand. In common usage, a building separation joint.

Exposed aggregate finish A concrete surface in which the coarse aggregate is revealed.

Exposed grid A framework for an acoustical ceiling that is visible from below after the ceiling is completed.

Exposure durability classification A system for rating the expected resistance of a wood panel product to weathering.

Extended-life admixture A substance that retards the onset of the curing reaction in mortar so that the mortar may be used over a protracted period of time after mixing.

Extended set-control admixture A substance that retards the onset of the curing reaction in concrete or mortar so that the material may be used over a protracted period of time after mixing.

Extensive green roof A green roof with a relatively shallow soil, planted with low-maintenance, drought-tolerant plant materials.

Exterior insulation and finish system (EIFS) A cladding system that consists of a thin layer of reinforced stucco applied directly to the surface of an insulating plastic foam board.

External flashing In masonry, a flashing that is not concealed within the wall, usually at the roof level or top of the wall.

External gutter A gutter hung off the edge of a roof, external to the roof construction itself.

Extrados The convex surface of an arch.

Extrusion The process of squeezing a material through a shaped orifice to produce a linear element with the desired cross section; an element produced by this process.

F

Fabricator The company that prepares structural steel members for erection; any entity that assembles building components prior to arrival on the construction site.

Facade An exterior face of a building.

Face brick A brick selected on the basis of appearance and durability for use in the exposed surface of a wall.

Face nail A nail driven through the side of one wood member into the side of another.

Face shell The portion of a hollow concrete masonry unit that forms the face of the wall.

Fahrenheit A temperature scale on which the boiling point of water is fixed at 212 degrees and the freezing point at 32 degrees.

Fanlight A semicircular or semielliptical window above an entrance door, often with radiating muntins that resemble a fan.

Fascia The exposed vertical face of an eave.

Fast track construction A method of providing design and construction services in which design and construction overlap in time; also called phased construction.

Faying surface The contacting surfaces of steel members joined with a slip-critical connection.

Felt A thin, flexible sheet material made of soft fibers pressed and bonded together. In building practice, a thick paper or a sheet of glass or plastic fibers.

Ferrous metal Any iron-based metal.

Ferrous steel In common usage, steel unprotected from corrosion by either galvanizing or alloying.

Fibrous reinforcing Short fibers of glass, steel, or polypropylene mixed into concrete to act as either microfiber reinforcing or macrofiber reinforcing.

Fieldstone Rough building stone gathered from river beds and fields.

Figure The surface pattern of the grain of a piece of smoothly finished wood or stone.

Filigree precast concrete A hybrid concrete system in which precast concrete sections are used as permanent formwork for cast in place concrete.

Fillet A rounded inside intersection between two surfaces that meet at an angle.

Fillet weld A weld at the inside intersection of two metal surfaces that meet at right angles.

Fine aggregate Sand used in concrete, mortar, or plaster mixes.

Fine-grained soil Soil with particles 0.003 inch (0.075 mm) or less in size; silts and clays.

Finger joint A glued end connection between two pieces of wood, using an interlocking pattern of deeply cut “fingers.” A finger joint creates a large surface for the glue bond, to allow it to develop the full tensile strength of the wood it connects.

Finial A slender ornament at the top of a roof or spire.

Finish Exposed to view; material that is exposed to view.

Finish carpenter One who does finish carpentry.

Finish carpentry The wood components exposed to view on the interior of a building, such as window and door casings, baseboards, bookshelves, and the like; may also refer to exterior finish carpentry, such as exterior trim, deck railings, and similar items.

Finish coat The final coat of a paint or other finishing system.

Finish-coat plaster The final coat of plaster, applied over gypsum base or one or more applications of base-coat plaster.

Finish floor The floor material exposed to view, as differentiated from the subfloor, which is the loadbearing floor surface beneath.

Finish lime A fine grade of quicklime used in finish-coat gypsum plasters and in ornamental plaster work; also called lime putty.

Finish nail A relatively thin nail with a very small head, used for fastening trim and other finish woodwork items.

Fire area In the International Building Code, an area within a building bounded by fire-resistant construction. Fire area size, occupant load, and location within the building are used to determine automatic sprinkler requirements.

Fire barrier In the International Building Code, a fire-resistant wall intended to deter the spread of fire, used to separate exit stair enclosures, differing occupancies, and fire areas.

Fireblocking Wood or other material used to partition concealed spaces within combustible framing, intended to restrict the spread of fire within such spaces.

Firebox The part of a fireplace, stove, or furnace in which fuel is combusted.

Firebrick A brick made to withstand very high temperatures, as in a fireplace, furnace, or industrial chimney.

Firecut A sloping end cut on a wood beam or joist where it enters a masonry wall. The purpose of the firecut is to allow the wood member to rotate out of the wall without prying the wall apart if the floor or roof structure burns through in a fire.

Fire door A fire-resistant door, used in fire-resistance rated partitions and walls.

Fire partition In the International Building Code, a fire-resistant wall intended to deter the spread of fire, used to separate tenant spaces, dwelling units, and corridors from surrounding areas of a building.

Fireproofing Material used around a steel (or concrete) structural element to insulate it against excessive temperatures in case of fire.

Fire protective glazing Fire-rated glass for use in fire doors, fire windows, and other protected openings that does not meet all of the requirements for use as a fire-resistance rated wall assembly.

Fire-rated glass Glass that is capable of retaining its integrity in an opening after being exposed to fire. See also Fire protective glazing, glass fire wall.

Fire resistance rating The time, in hours or fractions of an hour, that a material or assembly will resist fire exposure as determined by ASTM E119.

Fire resistant Noncombustible; slow to be damaged by fire; forming a barrier to the passage of fire.

Fire-resistive glazing See Glass fire wall.

Firestopping A component or mastic installed in an opening through a floor or around the edge of a floor to retard the passage of fire; frequently used interchangeably with fireblocking.

Fire wall A wall extending from foundation to roof, required under a building code to separate buildings, or parts of buildings, as a deterrent to the spread of fire.

Fire zone A legally designated area of a city in which construction must meet established standards of fire resistance and/or combustibility.

Firing The process of converting dry clay into a ceramic material through the application of intense heat.

First cost The cost of construction, not including operational costs.

Fixed window Glass that is immovably mounted in a wall.

Flagstone Flat stones used for paving or flooring.

Flame-spread rating A measure of the rapidity with which fire will spread across the surface of a finish material as determined by ASTM standard E84.

Flange A projecting crosspiece of a wide-flange or channel profile; a projecting fin.

Flash cove A detail in which a sheet of resilient flooring is turned up at the edge and finished against the wall to create an integral baseboard.

Flashing A thin, continuous sheet of metal, plastic, rubber, or waterproof paper used to prevent the passage of water through a joint in a wall, roof, or chimney.

Flat-grain lumber Dimension lumber sawed in such a way that annual rings are oriented close to parallel with the face. See also Vertical grain lumber.

Flat seam A sheet metal roofing seam that is formed flat against the surface of the roof.

Flemish bond Brickwork laid with each course consisting of alternating headers and stretchers.

Flitch-sliced veneer A thin sheet of wood cut by passing a block of wood vertically against a long, sharp knife.

Float A small platform suspended on ropes from a steel building frame to permit ironworkers to work on a connection; a trowel with a slightly rough surface used in an intermediate stage of finishing a concrete slab; as a verb, to use a float for finishing concrete.

Float glass Glass sheet manufactured by cooling a layer of molten glass on a bath of molten tin.

Floating floor Wood or laminate flooring that is not fastened or adhered to the subfloor.

Floating foundation A foundation placed at depth such that the weight of the soil removed is close to the weight of the building being supported.

Flocculated Having a “fluffy” microstructure such as that of clay particles in which the platelets are randomly oriented.

Flood test The submersion of a horizontal waterproofing system, usually for an extended period of time, to check for leaks.

Floor joist See Joist.

Flue A passage for smoke and combustion products from a furnace, stove, water heater, or fireplace.

Fluid-applied roof membrane A roof membrane applied in one or more coats of a liquid that cure to form an impervious sheet.

Fluoropolymer A highly stable organic compound used as a finish coating for building cladding.

Flush Smooth, lying in a single plane.

Flush door A door with smooth planar faces.

Flush glazing See Structural silicone flush glazing.

Flux A material added to react chemically with impurities and remove them from molten metal. Fluxes are used both in steelmaking and in welding. Welding fluxes serve the additional purpose of shielding the molten weld metal from the air to reduce oxidation and other undesirable effects.

Fly ash Dust collected in the stacks of coal-fired power plants, used as a supplementary cementitious material in concrete and mortar.

Flying formwork Large sections of slab formwork that are moved by crane.

Fly rafter A rafter in a rake overhang.

F-number An index number expressing the statistical flatness or levelness of a concrete slab.

Foil-backed gypsum board Gypsum board with aluminum foil laminated to its back surface to act as a vapor retarder and thermal insulator.

Folded plate A roof structure whose strength and stiffness derive from a pleated or folded geometry.

Footing The part of a foundation that spreads a load from the building across a broader area of soil.

Forced-air system A furnace and/or cooling coil and ductwork that heat and/or cool air and deliver it, driven by a fan, to the rooms of a building.

Form deck Thin, corrugated steel sheets that serve as permanent formwork for a reinforced concrete deck.

Form release compound A substance applied to concrete formwork to prevent concrete from adhering.

Form tie A steel or plastic rod with fasteners on either end, used to hold together the two surfaces of formwork for a concrete wall.

Form tie hole A depression, typically conical in shape, in a cast-in-place concrete wall that remains after the protruding portions of a form tie are removed.

Formwork Structures, usually temporary, that serve to give shape to poured concrete and to support it and keep it moist as it cures.

Foundation The portion of a building that transmits structural loads from the building into the earth.

Framed connection A shear connection between steel members made by means of steel angles or plates connecting to the web of the beam or girder.

Framing plan A diagram showing the arrangement and sizes of the structural members in a floor or roof.

Framing square An L-shaped measuring tool used by carpenters to lay out right-angle cuts as well as more complicated cuts, such as those required for stairs and sloping roof rafters.

Freestone Fine-grained sedimentary rock that has no planes of cleavage or sedimentation along which it is likely to split.

Free water In wood, water held within the cavities of the cells. See also Bound water.

Freeze protection admixture A concrete or mortar additive, used to allow curing under conditions of low ambient temperature.

French door A symmetrical pair of glazed doors hinged to the jambs of a single frame and meeting at the center of the opening.

Frictional soil A soil such as sand that has little or no attraction between its particles and derives its strength from geometric interlocking of the particles; also called a cohesionless soil.

Friction connection See Slip-critical connection.

Frit Ground-up colored glass that is heat-fused to lights of glass to form functional or decorative patterns.

Frost line The depth in the earth to which the soil can be expected to freeze during a severe winter.

Fully restrained moment connection A steel frame moment connection sufficiently rigid such that the geometric angles between connected pieces remain unchanged during normal loading; previously referred to as an “AISC Type 1” connection.

Furring channel A formed sheet metal furring strip.

Furring strip A length of wood or metal attached to a masonry or concrete wall to permit the attachment of finish materials to the wall using screws or nails; any linear material used to create a spacial separation between a finish material and an underlying substrate.

G

Gable The triangular wall beneath the end of a gable roof.

Gable roof A roof consisting of two oppositely sloping planes that intersect at a level ridge.

Gable vent A screened, louvered opening in a gable, used for exhausting excess heat and humidity from an attic.

Gage See Gauge.

Galling Chafing or tearing of one material against another under extreme pressure.

Galvanic couple A pair of metals with differing electrochemical potential, between which electrical current will flow if the metals are placed in a conducting medium.

Galvanic series A list of metals in order of their relative electrochemical potential when immersed in a given conducting medium.

Galvanized steel Steel with a zinc coating for the purpose of providing protection from corrosion.

Galvanizing The application of a zinc coating to steel.

Gambrel A roof shape consisting of two superimposed levels of gable roofs with the lower level at a steeper pitch than the upper.

Gantt chart A graphic representation of a construction schedule, using a series of horizontal bars representing the duration of various tasks or groups of tasks that make up the project.

Gasket A dry, resilient material used to seal a joint between two rigid assemblies by being compressed between them.

Gauge A measure of the thickness of sheet material. Lower gauge numbers signify thicker sheets; also spelled “gage.”

Gauged brick A brick that has been rubbed on an abrasive stone to reduce it to a trapezoidal shape for use in an arch.

Gauging plaster A gypsum plaster formulated for use in combination with finishing lime in finish coat plaster.

General contractor A construction entity with responsibility for the overall conduct of a construction project.

Geotextile A synthetic cloth used beneath the surface of the ground to stabilize soil or promote drainage.

GFRC See Glass-fiber-reinforced concrete.

Girder A horizontal beam that supports other beams; a very large beam, especially one that is built up from smaller elements.

Girt A horizontal beam that supports wall cladding between columns.

Glass block A hollow masonry unit made of glass.

Glass fiber batt A thick, fluffy, nonwoven insulating blanket of filaments spun from glass.

Glass-fiber-reinforced concrete (GFRC) Concrete with a strengthening admixture of short, alkali-resistant glass fibers.

Glass fire wall Fire-rated glass meeting all of the requirements for use as a fire-resistance rated wall assembly; also called fire-resistive glazing.

Glass mullion system A method of constructing a large glazed area by stiffening the sheets of glass with perpendicular glass ribs.

Glaze A glassy finish on a brick or tile; as a verb, to install glass.

Glazed structural clay facing tile A hollow clay block with glazed faces, usually used for constructing interior partitions.

Glazier One who installs glass.

Glazier's points Small pieces of metal driven into a wood sash to hold glass in place.

Glazing The act of installing glass; the transparent material (most often glass) in a glazed opening; as an adjective, referring to materials used in installing glass, for example “glazing tape.”

Glazing compound Any of several types of mastic used to bed small lights of glass in a frame.

Glue-laminated wood A wood member made up of a large number of small strips of wood glued together.

Glulam A short expression for glue-laminated wood.

Grade A classification of size or quality for an intended purpose; to classify as to size or quality.

Grade The surface of the ground; to move earth for the purpose of bringing the surface of the ground to an intended level or profile.

Grade beam A reinforced concrete beam that transmits the load from a bearing wall into spaced foundations such as pile caps or caissons.

Grain In wood, the direction of the longitudinal axes of the wood fibers or the figure formed by the fibers. In stone, see Quarry bed.

Granite Igneous rock with visible crystals of quartz and feldspar.

Green building Sustainable building; energy-efficient building; See also Sustainability.

Green roof A roof covered with soil and plant materials; eco-roof; vegetated roof.

Groove weld A weld made in a groove, created by beveling or milling the edges of the mating pieces of metal.

Ground A strip attached to a wall or ceiling to establish the level to which plaster should be applied.

Grout A high-slump mixture of portland cement, aggregates, and water, which can be poured or pumped into cavities in concrete or masonry for the purpose of embedding reinforcing bars and/or increasing the amount of loadbearing material in a wall; a specially formulated mortarlike material for filling under steel baseplates and around connections in precast concrete framing; a mortar used to fill joints between ceramic tiles or quarry tiles.

Gunnable sealant A sealant material that is extruded in liquid or mastic form from a sealant gun.

Gusset plate A flat steel plate used to connect the members of a truss; a stiffener plate.

Gutter A channel to collect rainwater and snowmelt at the eave of a roof.

GWB Gypsum wallboard; see Gypsum board.

Gypsum An abundant mineral; chemically, hydrous calcium sulfate.

Gypsum backing board A lower-cost gypsum panel intended for use as an interior layer in multilayer constructions of gypsum board.

Gypsum board An interior facing panel consisting of a gypsum core sandwiched between paper faces. Also called drywall, plasterboard.

Gypsum lath Sheets of gypsum board manufactured specifically for use as a plaster base.

Gypsum plaster Plaster whose cementing substance is calcined gypsum; used almost exclusively for interior finish plaster work.

Gypsum sheathing panel A water-resistant, gypsum-based sheet material used for exterior sheathing.

Gypsum wallboard (GWB) See Gypsum board.

H

Hammerhead boom crane A heavy-duty lifting device that uses a tower-mounted horizontal boom that may rotate only in a horizontal plane.

Hardboard A very dense panel product, usually with at least one smooth face, made of highly compressed wood fibers.

Hardwood Wood from deciduous (broadleaf) trees.

Hawk A square piece of sheet metal with a perpendicular handle beneath, used by a plasterer to hold a small quantity of wet plaster and transfer it to a trowel for application to a wall or ceiling.

HDO See High-density overlay.

Head The horizontal top portion of a window or door.

Header In framed construction, a member that carries other perpendicular framing members, such as a beam above an opening in a wall or a joist supporting other joists where they are interrupted by a floor opening. In steel construction, a beam that spans between girders. In masonry construction, a brick or other masonry unit that is laid across two wythes with its end exposed in the face of the wall.

Head jamb See Head.

Head joint The vertical layer of mortar between ends of masonry units.

Hearth The noncombustible floor area outside a fireplace opening.

Heartwood The dead wood cells in the center region of a tree trunk.

Heat-fuse To join by softening or melting the edges with heat and pressing them together.

Heat of hydration The thermal energy given off by concrete or gypsum as it cures.

Heat-strengthened glass Heat-treated glass that is not as strong as tempered glass, and that may not be used as safety glazing.

Heat-treated glass Glass that is strengthened by a heat treatment process; either heat-strengthened glass or tempered glass.

Heaving The forcing upward of ground or buildings by the action of frost or pile driving.

Heavy timber construction A type of wood construction made from large wood members and solid timber decking in a post and beam configuration; in the International Building Code, buildings of Type IV HT construction, consisting of heavy timber interior construction and noncombustible exterior walls, are considered to have moderate fire-resistive properties.

High-density overlay (HDO) A heavy weight, resin-treated overlay applied to plywood panels to achieve a smoother, more durable face.

High-lift grouting A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in story-high increments.

High-range sealant A sealant that is capable of a high degree of elongation without rupture.

High-range water-reducing admixture See Superplasticizer.

High-reactivity kaolin See Metakaolin.

High-strength bolt A bolt designed to connect steel members by clamping them together with sufficient force that the load is transferred between them by friction.

High-volume fly ash concrete (HVFA concrete) A concrete in which a high percentage of cementing substance is fly ash rather than portland cement.

Hip The diagonal intersection of planes in a hip roof.

Hip rafter A roof rafter at the intersection of two sloping roof planes. See also Common rafter.

Hip roof A roof consisting of four sloping planes that intersect to form a pyramidal or elongated pyramid shape.

Hollow brick Clay brick with up to 60 percent void area.

Hollow concrete masonry Concrete masonry units that are manufactured with open cores, such as ordinary concrete blocks.

Hollow-core door A door consisting of two face veneers separated by an airspace, with solid wood spacers around the four edges. The face veneers are usually connected by a grid of thin spacers within the airspace.

Hollow-core slab A precast concrete slab element that has internal longitudinal cavities to reduce its self-weight.

Hollow structural section (HSS). Hollow steel cylindrical or rectangular shapes made to be used as structural members; also called structural tubing.

Hook A semicircular bend in the end of a reinforcing bar, made for the purpose of anchoring the end of the bar securely into the surrounding concrete.

Hopper window A window whose sash pivots on an axis along or near the sill and that opens by tilting toward the interior of the building.

Horizontal force A force whose direction of action is horizontal or nearly horizontal. See also Lateral force.

Horizontal reinforcing Steel reinforcing that runs horizontally in a masonry wall in the form of either welded grids of small diameter metal rods or larger conventional reinforcing bars.

Hose stream test A standard laboratory test to determine the relative ability of a building assembly to stand up to water from a fire hose after a specified period of fire testing.

Hot-dip galvanizing A method of galvanizing in which a steel member or assembly is dipped into a bath of molten zinc.

Hot-rolled steel Steel formed into its final shape by passing it between rollers while it is very hot.

Housewrap A synthetic sheet material with water-resistive and air-resistive properties used as a substitute for asphalt-saturated felt or building paper to provide a protective layer in an exterior wall assembly.

HSS See Hollow structural section.

HVFA concrete See High-volume fly ash concrete.

Hydrated lime Quicklime mixed with water, either in the factory or on the job site; an ingredient in masonry mortars, portland cement plaster, and gypsum plasters, to which materials it imparts properties such as workability, bulk, and smoothness; chemically, calcium hydroxide; also called slaked lime.

Hydration The process by which cements combine chemically with water to harden.

Hydraulic cements Cementitious materials, such as portland cement or blast furnace slag, that harden by reacting with water and whose hardened products are not water soluble. Nonhydraulic cements, such as lime, can also be mixed with pozzolans to create cements with hydraulic properties.

Hydronic heating system A system that circulates warm water through convectors to heat a building.

Hydrostatic pressure Pressure exerted by standing water.

Hygroscopic Readily absorbing and retaining moisture.

Hyperbolic paraboloid shell A concrete roof structure with a saddle shape.

I

IBC See International Building Code and International Residential Code.

I-beam (obsolete term) An American Standard section of hot-rolled steel.

Ice and water shield See Rubberized underlayment.

Ice barrier A sheet material, usually rubberized underlayment or sheet metal, applied to the lower portions of sloped roofs in cold climates to protect against ice dams.

Ice dam An obstruction along the eave of a roof, caused by the refreezing of water emanating from melting snow on the roof surface above.

ICF See Insulating concrete form.

Igneous rock Rock formed by the solidification of magma.

IIC See Impact Isolation Class.

I-joist A manufactured wood framing member whose cross-sectional shape resembles the letter I.

Impact Isolation Class (IIC) An index of the extent to which a floor assembly transmits impact noise from a room above to the room below.

Impact noise Noise generated by footsteps or other impacts on a floor.

Impact wrench A device for tightening bolts and nuts by means of rapidly repeated torque impulses produced by electrical or pneumatic energy.

Incising Short, repetitive cuts made in the surface of a wood member to increase its absorption of treatment chemicals.

Ingot A large block of cast metal.

Insulating concrete form (ICF) A system of lightweight components, most commonly made of rigid polystyrene insulating foam, used as permanent formwork for the casting of concrete walls.

Insulating glass A glazing unit made up of two or more sheets of glass with an airspace in between.

Insulating glass unit (IGU) See Insulating glass.

Intensive green roof A green roof with relatively deep soil capable of supporting a broad variety of plants and shrubs.

Internal drainage Providing a curtain wall with hidden channels and weep holes to remove any water that may penetrate the exterior layers of the wall.

Internal flashing In masonry, a flashing concealed with the masonry; also called a concealed or through-wall flashing.

Internal gutter A gutter built into a roof assembly.

International Building Code (IBC) and International Residential Code (IRC) The predominant U.S. model building codes.

Interstitial ceiling A suspended ceiling with sufficient structural strength to support workers safely as they install and maintain mechanical and electrical installations above the ceiling.

Intrados The concave surface of an arch.

Intumescent coating A paint or mastic that expands to form a stable, insulating char when exposed to fire.

Inverted roof A membrane roof assembly in which the thermal insulation lies above the membrane.

IRC See International Building Code and International Residential Code.

Iron In pure form, a metallic element. In common usage, ferrous alloys other than steels, including cast iron and wrought iron.

Iron dog A heavy U-shaped staple used to tie the ends of heavy timbers together.

Ironworker A skilled laborer who erects steel building frames or places reinforcing bars in concrete construction.

Isocyanurate foam A thermosetting plastic foam with thermal insulating properties.

Isolation joint A type of structure/enclosure joint used with concrete slabs on grade to allow differential movement where they abut adjacent walls and columns.

J

Jack A device for exerting a large force over a short distance, usually by means of screw action or hydraulic pressure.

Jack rafter A shortened rafter that joins a hip or valley rafter.

Jack stud A shortened stud that carriers a header above a wall opening; also called a trimmer stud.

Jamb The vertical side of a door or window.

Jet burner A torch that burns fuel oil and compressed air, used in quarrying granite.

Joist One of a parallel array of light, closely spaced beams used to support a floor deck (floor joist) or low-slope roof (ceiling joist).

Joist band A broad, shallow concrete beam that supports one-way concretejoists whose depths are identical to its own.

Joist girder A light steel truss used to support open-web steel joists.

Joist hanger A sheet metal device used to create a structural connection where a joist is framed into a header or a ledger.

K

Keenes cement A proprietary, dense, crack-resistant gypsum plaster formulation.

Key A slot formed into a concrete surface for the purpose of interlocking with a subsequent pour of concrete; a slot at the edge of a precast member into which grout will be poured to lock it to an adjacent member; a mechanical interlocking of plaster with lath.

Kiln A furnace for firing clay or glass products; a heated chamber for seasoning wood; a furnace for manufacturing quicklime, gypsum hemihydrate, or portland cement.

King stud A full-length stud nailed alongside a jack stud.

Knee wall A short wall under the slope of a roof.

Knot A growth characteristic in wood, occurring where a branch joins the trunk of the tree from which the wood has been sawed.

kPa Kilopascal, a unit of pressure equal to 1 kilonewton per square meter.

L

Labyrinth A cladding joint design in which a series of interlocking baffles prevents drops of water from penetrating the joint by momentum.

Lacquer A coating that dries extremely quickly through evaporation of a volatile solvent.

Lagging Planks placed between soldier beams to retain earth around an excavation.

Lag screw A large-diameter wood screw with a square or hexagonal head.

Laminate As a verb, to bond together in layers; as a noun, a material produced by bonding together layers of material.

Laminated glass A glazing material consisting of outer layers of glass laminated to an inner layer of transparent plastic.

Laminated strand lumber (LSL) Wood members made up of long shreds of wood fiber joined with a binder.

Laminated veneer lumber (LVL) Structural composite lumber made up of thin wood veneers joined with glue.

Laminated wood See Glue-laminated wood.

Landing A platform in or at either end of a stair.

Lap joint A connection in which one piece of material is placed partially over another piece before the two are fastened together.

Lateral force A force acting generally in a horizontal direction, such as wind, earthquake, or soil pressure against a foundation wall.

Lateral thrust The horizontal component of the force produced by an arch, dome, vault, or rigid frame.

Latewood See Summerwood.

Latex caulk A low-range sealant based on a synthetic latex.

Latex/polymer modified portland cement mortar A tile setting mortar similar to dry-set mortar, but with additives that improve the cured mortar's freeze-thaw resistance, flexibility, and adhesion; used for thin-set tile applications.

Lath (rhymes with “math”) A base material to which plaster is applied.

Lathe (rhymes with “bathe”) A machine in which a piece of material is rotated against a sharp cutting tool to produce a shape, all of whose cross sections are circles; a machine in which a log is rotated against a long knife to peel a continuous sheet of veneer.

Lather (rhymes with “rather”) One who applies lath.

Lay-in panel A finish ceiling panel that is installed merely by lowering it onto the top of the metal grid components of the ceiling.

Lead (rhymes with “bed”) A soft, easily formed nonferrous metal, dull gray in color.

Lead (rhymes with “bead”) In masonry work, a corner or wall end accurately constructed with the aid of a spirit level to serve as a guide for placing the bricks in the remainder of the wall.

Leader (rhymes with “feeder”) See Downspout.

Leaf The moving portion of a door.

Lean construction Methods of construction and its management that emphasize efficiency, elimination of waste, and continuous improvement in quality.

Ledger A horizontal wood member fastened to a wall or beam to which the ends of joists may be connected.

Lehr A chamber in which glass is annealed.

Let-in bracing Diagonal bracing that is nailed into notches cut in the face of the studs so as not to increase the thickness of the wall.

Level cut A saw cut that produces a level surface in a sloping rafter when the rafter is in its final position. See also Plumb cut.

Leveling plate A steel plate placed in grout on top of a concrete foundation to create a level bearing surface for the lower end of a steel column.

Lewis A device for lifting a block of stone by means of friction exerted against the sides of a hole drilled in the top of the block.

Life-cycle cost A cost that takes into account both the first cost and the costs of maintenance, replacement, fuel consumed, monetary inflation, and interest over the life of the object being evaluated.

Lift-slab construction A method of building multistory sitecast concrete buildings by casting all the slabs in a stack on the ground, then lifting them up the columns with jacks and welding them in place.

Light A sheet of glass, also spelled “lite.”

Light gauge steel stud A length of thin sheet metal formed into a stiff shape and used as a wall framing member.

Light to solar gain (LSG) ratio The visible light transmittance of a glazing unit divided by the solar heat gain coefficient, a measure of the energy-conserving potential of the unit.

Lightweight aggregate Low-density aggregate used to make lightweight concrete, mortar, and plaster; in concrete, aggregate with a density of less than 70 lb/ft³ (1120 kg/m³).

Lignin The natural cementing substance that binds together the cellulose in wood.

Lime A nonhydraulic cementitious material, used as an ingredient in mortars and plasters. See also Hydrated lime, Quicklime.

Lime mortar Masonry mortar made from a mix of lime, sand, and water; used principally in the restoration of historic structures.

Lime putty See Finish lime.

Limestone A sedimentary rock consisting of calcium carbonate, magnesium carbonate, or both.

Linear metal ceiling A finish ceiling whose exposed face is made up of long, parallel elements of sheet metal.

Liner A piece of marble doweled and cemented to the back of another sheet of marble.

Line wire Wire stretched across wall studs as a base for the application of metal mesh and stucco.

Linoleum A resilient floor covering material composed primarily of ground cork and linseed oil on a burlap or canvas backing.

Lintel A beam that carries the load of a wall across a window or door opening.

Liquid sealant Gunnable sealant.

Lite See Light.

Live load Nonpermanent loads on a building caused by the weights of people, furnishings, machines, vehicles, and goods in or on the building.

Load A weight or force acting on a structure.

Loadbearing Supporting a superimposed weight or force.

Loadbearing wall See Bearing wall.

Load indicator washer A disk placed under the head or nut of a high-strength bolt to indicate sufficient tensioning of the bolt by means of the deformation of ridges on the surface of the disk; also called a direct tension indicator washer.

Lockpin and collar fastener A boltlike device that is passed through holes in structural steel components, held in very high tension, and closed with a steel ring that is squeezed onto its protruding shank.

Lockstrip gasket A synthetic rubber strip compressed around the edge of a piece of glass or a wall panel by inserting a spline (lockstrip) into a groove in the strip.

Longitudinal shrinkage In wood, shrinkage along the length of the log.

Lookout A short rafter, running perpendicular to the other rafters in the roof, which supports a rake overhang.

Louver A construction of numerous sloping, closely spaced slats used to diffuse air or to prevent the entry of rainwater into a ventilating opening.

Low-e coating See Low-emissivity coating.

Low-emissivity coating A surface coating for glass that selectively reflects solar radiation of different wavelengths so as to permit high visible light transmittance while reflecting some or all types of infrared (heat) radiation.

Low-lift grouting A method of constructing a reinforced masonry wall in which the reinforcing bars are embedded in grout in increments not higher than 4 feet (1200 mm).

Low-range sealant A sealant that is capable of only a slight degree of elongation prior to rupture; a caulk.

Low-slope roof A roof that is pitched so near to horizontal that it must be made waterproof with a continuous membrane rather than shingles; commonly and inaccurately referred to as a “flat roof.” In the International Building Code, a roof with a slope of less than 2:12 (17 percent).

LSG See Light to solar gain ratio.

LSL See Laminated strand lumber.

Luffing-boom crane A heavy-duty lifting device that uses a tower-mounted boom that may rotate in any vertical plane as well as in a horizontal plane.

LVL See Laminated veneer lumber.

M

Machine grading The grading of wood for its structural properties, performed by automated machinery, as distinct from visual gpading.

Macrofiber reinforcing In concrete, fibrous reinforcement capable of providing resistance to drying shrinkage and thermal stresses, and in some specialized concretes, also capable of acting as primary reinforcing. See also Microfiber reinforcing.

Mandrel A stiff steel core placed inside the thin steel shell of a sitecast concrete pile to prevent it from collapsing during driving.

Mansard A roof shape consisting of two superimposed levels of hip roofs with the lower level at a steeper pitch than the upper.

Manufactured home. A transportable house that is entirely factory built on a steel underframe supported by wheels; euphemistically referred to as a mobile home.

Marble A metamorphic rock formed from limestone by heat and pressure.

Mason One who builds with bricks, stones, or concrete masonry units; one who works with concrete.

Masonry Brickwork, concrete blockwork, and stonework.

Masonry cement A hydraulic cement made from a blend of portland cement, lime and other dry admixtures designed to increase the workability of the mortar. See also Cement-lime mortar.

Masonry opening The clear dimension required in a masonry wall for the installation of a specific window or door unit.

Masonry unit A brick, stone, concrete block, glass block, or hollow clay tile intended to be laid in mortar.

Masonry veneer A single wythe of masonry used as a facing over a frame of wood or metal.

MasterFormat The copyrighted title of a uniform indexing system for construction specifications, as created by the Construction Specifications Institute and Construction Specifications Canada.

Mastic A viscous, doughlike, adhesive substance; can be any of a large number of formulations for different purposes such as sealants, adhesives, glazing compounds, or roofing cements.

Mat foundation A single concrete footing that is essentially equal in area to the area of ground covered by the building.

Medium-density fiberboard (MDF) A fine-grained wood fiber and resin panel product.

Medium-density overlay (MDO) A medium-weight, resin-treated overlay applied to plywood panels to achieve a smoother, more durable face.

Medium-range sealant A sealant material that is capable of a moderate degree of elongation before rupture.

Meeting rail The wood or metal bar along which one sash of a double-hung, single-hung, or sliding window seals against the other.

Member An element of a structure such as a beam, girder, column, joist, piece of decking, stud, or component of a truss.

Membrane A sheet material that is impervious to water or water vapor.

Membrane fire protection A ceiling used to provide fire protection to the structural members above.

Metakaolin A white-colored natural pozzolan that enhances appearance, workability, and hardened properties of concrete; also called high reactivity metakaolin.

Metal decking Corrugated metal sheets used as the structural base for floors (“floor decking”) and roofs (“roof decking”) in steel frame construction. See also Celluar decking and Composite metal decking.

Metal lath A steel mesh used primarily as a base for the application of plaster.

Metallic-coated steel Steel sheet coated with zinc or zinc-aluminum for improved corrosion resistance.

Metamorphic rock A rock created by the action of heat or pressure on a sedimentary rock or soil.

Microfiber reinforcing In concrete, fibrous reinforcement against plastic shrinkage cracking. See also Macrofiber reinforcing.

Microsilica See Silica fume.

Middle strip The half-span-wide zone of a two-way concrete slab that lies midway between columns.

Mild steel Ordinary structural steel, containing less than three-tenths of 1 percent carbon.

Mill construction The traditional name for a construction type consisting of exterior masonry bearing walls and an interior framework of heavy timbers and solid timber decking; also called slow-burn construction. See also Heavy timber construction.

Milling Shaping or planing by using a rotating cutting tool.

Millwork Wood interior finish components of a building, including moldings, windows, doors, cabinets, stairs, mantels, and the like.

Minimum critical radiant flux exposure A measure of a material's resistance to ignition by the radiant heat of fire and hot gases in adjacent spaces, usually applied to flooring materials.

Miter A diagonal cut at the end of a piece; the joint produced by joining two diagonally cut pieces at right angles.

Mobile home See Manufactured home.

Model building code A code that is offered by a recognized national organization as worthy of adoption by state or local governments.

Modified bitumen A natural bitumen with admixtures of synthetic compounds to enhance such properties as flexibility, plasticity, and durability.

Modified bitumen roof membrane A multi-ply bituminous roof membrane made from plies of factory-manufactured modified bitumen sheets.

Modular Conforming to a multiple of a fixed dimension.

Modular green roof A green roof system in which all components are provided in self-contained, easily transported and installed trays or modules.

Modular home A house assembled on the site from boxlike factory-built sections.

Modulus of elasticity An index of the stiffness of a material, derived by measuring the elastic deformation of the material as it is placed under stress and then dividing the stress by the deformation.

Moisture barrier A membrane used to resist the migration of liquid water through a floor, wall, or roof.

Molding A strip of wood, plastic, or plaster with an ornamental profile.

Molding plaster A fast-setting gypsum plaster used for the manufacture of cast ornament.

Moment A force acting at a distance from a point in a structure so as to cause a tendency of the structure to rotate about that point. See also Bending moment, Moment connection.

Moment connection A connection between two structural members that is highly resistant to rotation between the members and therefore capable of transmitting bending moments between the connected members, as differentiated from a shear connection, which allows (slight) rotation. See also Fully restrained moment connection, Partially restrained moment connection, and Simple connection.

Moment-resisting frame A structural building frame, strengthened to resist lateral forces with moment connections between beams and columns.

Momentum The tendency of a moving body to continue to move in the same direction unless acted on by an outside force.

Monolithic Of a single massive piece.

Monolithic terrazzo A thin terrazzo topping applied to a concrete slab without an underbed.

Mortar A substance used to join masonry units, consisting of cementitious materials, fine aggregate, and water. See also Cement-lime mortar, Lime mortar.

Mortar bed tile See Thickset tile.

Mortar cement In masonry, a blend of portland cement, lime, and other additives, that produces mortar comparable in its bond strength properties to cement-lime mortar. See also Cement-lime mortar.

Mortise and tenon A joint in which a tonguelike protrusion (tenon) on the end of one piece is tightly fitted into a rectangular slot (mortise) in the side of the other piece.

Movement joint A line or plane along which movement is allowed to take place in a building or a surface of a building in response to such forces as moisture expansion and contraction, thermal expansion and contraction, foundation settling, and seismic forces.

MPa Megapascal, a unit of pressure equal to 1 meganewton per square meter.

Mud set tile See Thickset tile.

Mud slab A slab of weak concrete placed directly on the ground to provide a usually temporary working surface that is hard, level, and dry.

Mullion A vertical or horizontal bar between adjacent window or door units. A framing member in a metal-and-glass curtain wall.

Muntin A small vertical or horizontal bar between small lights of glass in a sash.

Muriatic acid Hydrochloric acid.

Mushroom capital A flaring conical head on a concrete column.

N

Nail A sharp-pointed metal pin used for fastening of wood.

Nail-base sheathing A sheathing material, such as wood boards or plywood, to which siding can be attached by nailing, as differentiated from one such as cane fiber board or plastic foam board that is too soft to hold nails.

Nail popping The loosening of nails holding gypsum board to a wall, caused by drying shrinkage of the studs.

Nail set A hardened steel punch used to drive the head of a nail to a level flush with or below the surface of the wood.

National Building Code of Canada (NBCC) The predominant Canadian model building code.

NBCC See National Building Code of Canada.

Near-infrared (NIR) radiation An invisible portion of the solar spectrum that accounts for over half of the total heat energy in solar radiation.

Needle beam A steel or wood beam threaded through a hole in a bearing wall and used to support the wall and its superimposed loads during underpinning of its foundation.

Needling The use of needle beams.

Negative-side waterproofing Waterproofing applied to the inner side of a wall, acting to resist water passage from the opposite side.

Neoprene Polychloroprene, a synthetic rubber.

NIR radiation See Near-infrared radiation.

Noble metal See Passive metal.

Noise Reduction Coefficient (NRC) An index of the proportion of incident sound that is absorbed by a surface, expressed as a decimal fraction of 1.

Nominal dimension An approximate dimension assigned to a piece of material as a convenience in referring to the piece.

Nonaxial In a direction not parallel to the long axis of a structural member.

Nonbearing Not carrying a load.

Nonhydraulic cements Cementitious materials, such as gypsum and lime, that remain water soluble after curing. See also Hydraulic cements.

Nonmovement joint A connection between materials or elements that is not designed to allow for movement.

Nonworking joint A joint that is not subjected to significant deformations.

Nosing The projecting forward edge of a stair tread.

NRC See Noise Reduction Coefficient.

Nut A steel fastener with internal helical threads, used to close a bolt.

O

o.c. Abbreviation for “on center,” meaning that the spacing of framing members is measured from the center of one member to the center of the next, rather than the clear spacing between members.

Occupancy group In the International Building Code, a definition of the types of activities that occur within the building or a part of the building, relating to considerations of life safety.

Ogee An S-shaped curve.

Oil-based caulk A low-range sealant made with linseed oil.

One-way action The structural action of a slab that spans between two parallel beams or bearing walls.

One-way concrete joist system A reinforced concrete framing system in which closely spaced concrete joists span between parallel beams or bearing walls.

One-way solid slab A reinforced concrete floor or roof slab that spans between parallel beams or bearing walls.

Open-truss wire stud A wall framing member in the form of a small steel truss.

Open-web steel joist A lightweight, prefabricated, welded steel truss used at closely spaced intervals to support floor or roof decking.

Optical-quality ceramic A transparent, glasslike material that is used as a firerated glazing sheet.

Optimum value engineering See Advanced framing techniques.

Ordinary construction A traditional building type with exterior masonry bearing walls and an interior structure of balloon framing

Organic soil Soil containing decayed vegetable and/or animal matter; topsoil.

Oriented strand board (OSB) A building panel composed of long shreds of wood fiber oriented in specific directions and bonded together under pressure.

Oriented strand lumber (OSL) Structural composite lumber made from shredded wood strands, coated with adhesive, and pressed into a rectangular cross section.

OSB See Oriented strand board.

OSL See Oriented strand lumber.

Oxidation Corrosion; rusting; rust; chemically, the combining with oxygen.

P

Package fireplace A factory-built fireplace that is installed as a unit.

Paint A heavily pigmented coating applied to a surface for decorative and/or protective purposes.

Pan A form used to produce the cavity between joists in a one-way concrete joist system.

Panel A broad, thin piece of wood; a sheet of building material such as plywood or particleboard; a prefabricated building component that is broad and thin, such as a curtain wall panel; a rectangular area within a truss bounded by two vertical interior members.

Panel door A wood door in which one or more thin panels are held by stiles and rails.

Panelized construction A method of prefabricated wood light frame construction, in which whole sections of walls or floors are framed and sheathed in the factory and then transported to the construction site for erection.

Panic hardware A mechanical device that opens a door automatically if pressure is exerted against the device from the interior of the building.

Parallel strand lumber (PSL) Structural composite lumber made of wood shreds oriented parallel to the long axis of each piece and bonded together with adhesive.

Parapet The region of an exterior wall that projects above the level of the roof.

Parging Portland cement plaster applied over masonry to make it less permeable to water.

Partially restrained moment connection A steel frame moment connection that is less rigid than a fully restrained moment connection but that still possesses a usable degree of resistance to rotation; previously referred to as an “AISC Type 3” connection.

Particleboard A building panel composed of small particles of wood bonded together under pressure.

Parting compound See Form release compound.

Partition An interior nonloadbearing wall.

Passive metal A metal relatively low on a galvanic series, tending to act as an cathode in galvanic couples; also called a noble metal.

Patterned glass Glass into which a texture has been rolled during manufacture.

Pattern rafter A wood rafter cut to size and shape and then used to trace cuts onto additional wood members so as to assure consistent dimensions among all rafters.

Paver A half-thickness brick used as finish flooring.

PEC See Pressure equalization chamber.

Pediment The gable end of a roof in classical architecture.

Penetrometer A device for testing the resistance of a material to penetration, usually used to make a quick, approximate determination of its compressive strength.

Penny (d) A designation of nail size.

Performance grade A rating used to indicate the relative weather resistance of a window.

Periodic kiln A kiln that is loaded and fired in discrete batches, as differentiated from a tunnel kiln, which is operated continuously.

Perlite Expanded volcanic glass, used as a lightweight aggregate in concrete and plaster and as an insulating fill.

Perm A unit of vapor permeance, a measure of a material's permeability to the diffusion of water vapor.

Permanent formwork Concrete formwork that remains permanently in place after concrete is poured and cured and becomes part of the finished construction.

Phased construction See Fast track construction.

Photochromic glass Glass that changes it optical properties in response to light intensity.

Photovoltaic Capable of converting light into electricity.

Pier A caisson foundation unit.

Pilaster A vertical, integral stiffening rib in a masonry or concrete wall.

Pile A long, slender piece of material driven into the ground to act as an element of a foundation.

Pile cap A thick slab of reinforced concrete poured across the top of a pile cluster to cause the cluster to act as a unit in supporting a column or grade beam.

Piledriver A machine for driving piles.

Pill test A test of a flooring material's propensity for flame spread when exposed to a burning tablet intended to simulate a dropped lit cigarette, match, or similar hazard.

Pintle A metal device used to transmit compressive forces between superimposed columns in Mill construction.

Pitch The slope of a roof or other plane, often expressed as inches of rise per foot of run; a dark, viscous hydrocarbon distilled from coal tar; a viscous resin found in wood.

Pitched roof A sloping roof.

Pivoting window A window that opens by rotating around its vertical centerline.

Plainsawing Sawing a log into dimension lumber without regard to the direction of the annual rings.

Plain slicing Cutting a log into veneers without regard to the direction of the annual rings.

Plan An architectural drawing, representing the layout of walls and floor areas as seen from above (“floor plan”) or ceilings as seen from below (“ceiling plan”).

Planing Smoothing the surface of a piece of wood, stone, or steel with a cutting blade.

Plank flooring Solid wood finish flooring members 3 inches (75 mm) or more in width.

Plaster A cementitious material, usually based on gypsum or portland cement, applied to lath or masonry in paste form to harden into a finish surface.

Plasterboard See Gypsum board.

Plaster of Paris See Calcined gypsum.

Plaster screeds Intermittent spots or strips of plaster used to establish the level to which a large plaster surface will be finished.

Plastic A synthetically produced giant molecule, mostly based on carbon chemistry.

Plasticity The ability to retain a shape attained by pressure deformation.

Plastic laminate flooring A finish material for floors that consists of a thin decorative and wearing layer of melamine laminate glued to a wood composite substrate.

Plastic lumber Lumberlike products with a plastic content of 50 percent or more. See also Structural-grade plastic lumber.

Plastic shrinkage cracking Cracking in freshly mixed concrete, most commonly in slabs, that occurs when the surface of the concrete dries too rapidly.

Plate A broad sheet of rolled metal ¼ inch (6.35 mm) or more thick; a twoway concrete slab; a horizontal top or bottom member in a platform frame wall structure.

Plate girder A large beam made up of steel plates, sometimes in combination with steel angles, that are welded, bolted, or riveted together.

Plate glass Glass of high optical quality, produced by grinding and polishing both faces of a glass sheet.

Platform frame A wooden building frame composed of closely spaced members nominally 2 inches (51 mm) thick in which the wall members do not run past the floor framing members.

Plenum The space between the ceiling of a room and the structural floor above, used as a passage for ductwork, piping, and wiring.

Plumb Vertical.

Plumb cut A saw cut that produces a vertical (plumb) surface in a sloping rafter after the rafter is in its final position. See also Level cut.

Plumbing up The process of making a steel building frame vertical and square.

Ply A layer, such as a layer of felt in a built-up roof membrane or a layer of veneer in plywood.

Plywood A wood panel composed of an odd number of layers of wood veneer bonded together under pressure.

PMR See Protected membrane roof.

Pneumatically placed concrete See Shotcrete.

Pointing The process of applying mortar to the surface of a mortar joint after the masonry has been laid, either as a means of finishing the joint or to repair a defective joint. Raked mortar joints can also be pointed with elastomeric sealant.

Pointing mortar Mortar used for the pointing of masonry joints, generally of relatively low strength and with good wok-ability and adhesion characteristics.

Poke-through fitting An electrical outlet that is installed by drilling a hole through a floor, inserting the outlet from above, and bringing in the wiring from the plenum below.

Polybutene tape A sticky, masticlike tape used to seal nonworking joints, especially between glass and mullions.

Polycarbonate An extremely tough, strong, usually transparent plastic used for window and skylight glazing, light fixture globes, door sills, and other applications.

Polyethylene A thermoplastic widely used in sheet form for vapor retarders, moisture barriers, and temporary construction coverings.

Polyisocyanurate foam see Isocyanurate foam.

Polymer A large molecule composed of many identical chemical units.

Polypropylene A plastic formed by the polymerization of propylene.

Polystyrene foam A thermoplastic foam with thermal insulating properties.

Polysulfide A high-range gunnable sealant.

Polyurethane Any of a large group of resins and synthetic rubber compounds used in sealants, varnishes, insulating foams, and roof membranes.

Polyurethane foam A thermosetting foam with thermal insulating properties.

Polyvinyl butyral (PVB) interlayer A transparent plastic used in the fabrication of laminated glass.

Polyvinyl chloride (PVC) A thermoplastic material widely used in construction products, including plumbing pipes, floor tiles, wall coverings, and roof membranes. Called “vinyl” for short.

Ponding The accumulation of standing water on a low-slope roof due to inadequate drainage.

Poorly graded soil See Well-sorted soil.

Poorly sorted soil See Well-graded soil.

Portal frame A rigid frame; two columns and a beam attached to one another with moment connections.

Portland cement A gray or white powder, composed principally of calcium silicates, which, when combined with water, hydrates to form the binder in concrete, mortar, and stucco.

Posttensioning Compressing the concrete in a structural member by tensioning high-strength steel tendons against it after the concrete has cured.

Pour To cast concrete; an increment of concrete casting carried out without interruption.

Powder coating A coating produced by applying a powder consisting of thermosetting resins and pigments, adhered to the substrate by electrostatic attraction, and fused into a continuous film in an oven.

Powder driven Inserted by a gunlike tool using energy provided by an exploding charge of gunpowder.

Pozzolan A supplementary cementitious material, such as fly ash, silica fume, and some naturally occurring shales and clays, that has few or no inherent cementitious properties but that, in the presence of moisture, can react with calcium hydroxide released by other cementitious materials to create a hydraulic cement product. The Romans mixed natural pozzolans with lime to make the first hydraulic cement.

Precast concrete Concrete cast and cured in a location other than its final position in the structure.

Predecorated gypsum board Gypsum board finished at the factory with a decorative layer of paint, paper, or plastic.

Prefabrication Construction that takes place in a factory or shop, rather than on the building site.

Preformed cellular tape sealant A sealant inserted into a joint in the form of a compressed sponge impregnated with compounds that cure to form a watertight seal.

Preformed joint filler A strip of rubbery or spongelike material designed to fit snugly into a gap between two materials.

Preformed solid tape sealant A sealant inserted into a joint in the form of a flexible strip of solid material.

Prehung door A door that is hinged to its frame in a factory or shop.

Prescriptive building code A set of legal regulations that mandate specific construction details and practices rather than establish performance standards.

Preservative-treated wood Wood that has been impregnated with preservative chemicals to increase its resistance to decay and biological attack; also commonly called pressure-treated wood.

Pressure equalization chamber (PEC) The wind-pressurized cavity in a rain-screen wall.

Pressure-equalized wall design Curtain wall design that relies on neutralization of wind pressures on both sides of a the exterior cladding to control water entry into the wall system. See also Rainscreen principle.

Pressure-treated wood Wood that has been impregnated with chemicals under pressure for the purpose of retarding decay or reducing combustibility.

Prestressed concrete Concrete that has been pretensioned or posttensioned.

Prestressing Applying an initial compressive stress to a concrete structural member, either by pretensioning or posttensioning.

Pretensioning Compressing the concrete in a structural member by pouring the concrete for the member around stretched high-strength steel strands, curing the concrete, and releasing the external tensioning force on the strands.

Prime window A window unit that is made to be installed permanently in a building.

Priming Covering a surface with a coating that prepares it to accept another coating or a sealant.

Protected membrane roof (PMR) A membrane roof assembly in which the thermal insulation lies above the membrane.

Protection board Semirigid sheet material used to cushion the outside of a foundation wall, particularly its waterproofing layer, from damage caused by rocks in the backfill material.

PSL See Parallel strand lumber.

Pultrusion The process of producing a shaped linear element by pulling glass fibers through a bath of uncured plastic, then through a heated, shaped die in which the plastic hardens.

Punty A metal rod used in working with hot glass.

Purlin A beam that spans across the slope of a steep roof to support the roof decking.

Putty A simple glazing compound used to seal around a small light.

PVB interlayer See Polyvinyl butyral interlayer.

PVC See Polyvinyl chloride.

Pyrolitic coating A coating applied at a very high temperature.

Q

Quarry An excavation from which building stone is obtained; the act of taking stone from the ground.

Quarry bed A plane in a building stone that was horizontal before the stone was cut from the quarry; also called grain.

Quarry sap Excess water found in rock at the time of its quarrying.

Quarry tile A large clay floor tile, usually unglazed.

Quartersawn Lumber sawn in such a way that the annual rings run roughly perpendicular to the face of each piece.

Quartersliced Veneer sliced in such a way that the annual rings run roughly perpendicular to the face of each veneer.

Quenching The rapid cooling of metal so as to alter its physical properties; a form of heat treatment.

Quicklime Produced by burning calcium carbonate found in limestone or sea shells; once hydrated, used as an ingredient in mortars and plasters; chemically, calcium oxide. See also Hydrated lime.

Quoin (pronounced “coin”) A corner reinforcing of cut stone or bricks in a masonry wall, usually done for decorative effect.

R

Radial shrinkage In wood, shrinkage perpendicular to the growth rings.

Rabbet A longitudinal groove cut at the edge of a member to receive another member; also called a rebate.

Radiant barrier A reflective foil or metal placed adjacent to an airspace in roof or wall assemblies as a deterrent to the passage of infrared energy.

Radiant heating system Providing heat to spaces and their inhabitants by heating one or more surfaces of each room. The heated surface is usually either the floor or the ceiling. Heat is usually provided either by electric resistance coils or by hot-water tubing.

Radiator See Convector.

Raft A mat footing.

Rafter A framing member that runs up and down the slope of a steep roof.

Rail A horizontal framing piece in a panel door; a handrail.

Rainscreen principle A theory by which wall cladding is made watertight by providing wind-pressurized air chambers behind joints to eliminate air pressure differentials between the outside and the inside that might transport water through the joints. See also Pressure-equalized wall design.

Rainscreen siding Siding systems that include a system of internal drainage, but not necessarily meeting all the criteria of a pressure-equalized wall design.

Raised access flooring See Access flooring.

Rake The sloping edge of a steep roof.

Raked mortar joint A mortar joint in which mortar has been removed from the portion of the joint closest to the surface of the masonry.

Raker A sloping brace for supporting sheeting around an excavation.

Ram A hydraulic piston device used for bending steel, tensioning steel strands in prestressed concrete, or lifting heavy loads.

Random stone masonry See Uncoursed stone masonry.

Ratchet A mechanical device with sloping teeth that allows one piece to be advanced against another in small increments, but not to move in the reverse direction.

Ray A tubular cell that runs radially in a tree trunk.

RBM See Reinforced brick masonry.

Rebar See Steel reinforcing bars.

Rebate See Rabbet.

Reflective coated glass Glass onto which a thin layer of metal or metal oxide has been deposited to reflect light and/or heat.

Reglet A slot, usually horizontal, and inclined in cross section, into which a flashing or roof membrane may be inserted in a concrete or masonry surface.

Reinforced brick masonry (RBM) Brickwork into which steel bars have been embedded to impart tensile strength to the construction.

Reinforced concrete Concrete work into which steel bars have been embedded to impart tensile strength to the construction.

Relative humidity A percentage representing the ratio of the amount of water vapor contained in a mass of air to the maximum amount of water it could contain under the existing conditions of temperature and pressure.

Relieved back A longitudinal groove or series of grooves cut from the back of a flat wood molding or flooring strip to minimize cupping forces and make the piece easier to fit to a flat surface.

Removable glazing panel A framed sheet of glass that can be attached to a window sash to increase its thermal insulating properties.

Replacement window A window unit that is designed to be installed easily in an opening left in a wall by a deteriorated window unit that has been removed.

Repointing The process of removing deteriorated mortar from the zone near the surface of a brick wall and inserting fresh mortar. See also Tuckpointing.

Reshoring Inserting temporary supports under concrete beams and slabs after the formwork has been removed to prevent overloading prior to full curing of the concrete.

Resilient clip A springy mounting device for plaster or gypsum board that helps reduce the transmission of sound vibrations through a wall or ceiling.

Resilient flooring A manufactured sheet or tile flooring made of asphalt, polyvinyl chloride, linoleum, rubber, or other elastic material.

Resin A natural or synthetic, solid or semisolid organic material of high molecular weight, used in the manufacture of paints, varnishes, and plastics.

Restraightening A step in the finishing of concrete slabs for the purpose of removing minor undulations produced during floating or troweling.

Retaining wall A wall that resists horizontal soil pressures at an abrupt change in ground elevation.

Retarding admixture An admixture used to slow the curing of concrete, mortar, or plaster.

Ridge beam A structural beam supporting the upper ends of rafters in a sloped roof, required where the rafters are not tied at their lower ends.

Ridge board A nonstructural framing member against which the upper ends of rafters are fastened.

Ridge vent A screened, water-shielded ventilation opening that runs continuously along the ridge of a gable roof.

Rigid connection A fully restrained moment connection.

Rigid frame Two columns and a beam or beams attached to one another with moment connections; a moment-resisting frame.

Rim joist See Band joist.

Rise A difference in elevation, such as the rise of a stair from one floor to the next or the rise per foot of run in a sloping roof.

Riser A single vertical increment of a stair; the vertical face between two treads in a stair; a vertical run of plumbing, wiring, or ductwork.

Rivet A structural fastener on which a second head is formed after the fastener is in place.

Rock anchor A posttensioned rod or cable inserted into a rock formation for the purpose of tying it together.

Rock wool An insulating material manufactured by forming fibers from molten rock.

Roofer One who installs roof coverings.

Roofing The material used to make a roof watertight, such as shingles, slate, tiles, sheet metal, or a roof membrane; the act of applying roofing.

Roof membrane A waterproof sheet or multiply assembly that protects a low-slope roof from water penetration.

Roof window Either an openable glazed unit installed in the sloping surface of a roof or, more specifically, a glazed roof unit with the inward sash operation to allow easy cleaning.

Rotary-sliced veneer A thin sheet of wood produced by rotating a log against a long, sharp knife blade in a lathe.

Rough arch An arch made from masonry units that are rectangular rather than wedge- shaped.

Rough carpentry Framing carpentry, as distinguished from finish carpentry.

Roughing in The installation of mechanical, electrical, and plumbing components that will not be exposed to view in the finished building.

Rough opening The clear dimensions of the opening that must be provided in a wall frame to accept a given door or window unit.

Rowlock A brick laid on its long edge, with its end exposed in the face of the wall.

RSI-value The metric equivalent of R-value.

Rubberized underlayment An adhered bituminous sheet material that self-heals around nails, applied to roof sheathing to prevent the entry of water; also called ice and water shield.

Rubble Unsquared stones.

Run Horizontal dimension in a stair or sloping roof.

Runner channel A steel member from which furring channels and lath are supported in a suspended plaster ceiling.

Running bond Brickwork consisting entirely of stretchers.

Runoff bar One of a pair of small rectangular steel bars attached temporarily at the end of a prepared groove for the purpose of permitting the groove to be filled to its very end with weld metal.

Run plaster ornament A linear molding produced by passing a profiled sheet metal or plastic template back and forth across a mass of wet plaster.

R-value A numerical measure of resistance to the flow of heat; the reciprocal of U-factor.

S

Safety glazing Glass or plastic glazing material that, when broken, does not create hazardous shards, permitted for use in locations in buildings at risk of occupant impact; typically tempered glass, laminated glass, or plastic.

Safing Fire-resistant material inserted into a space between a curtain wall and a spandrel beam or column to retard the passage of fire through the space.

Sand cushion terrazzo Terrazzo with an underbed that is separated from the structural floor deck by a layer of sand.

Sand-mold brick, sand-struck brick A brick made in a mold that was wetted and then dusted with sand before the clay was placed in it.

Sandstone A sedimentary rock formed from sand; classified by ASTM C119 in the Quartz-Based Dimension Stone group.

Sandwich panel A panel consisting of two outer faces of wood, metal, gypsum, or concrete bonded to a core of insulating foam.

Sapwood The living wood in the outer region of a tree trunk or branch.

Sash A frame that holds glass.

SBS See Styrene-butadiene-styrene.

SBX See Sodium borate.

Scab A piece of framing lumber nailed to the face of another piece of lumber.

Scarf joint A glued end connection between two pieces of wood, using a sloping cut to create a large surface for the glue bond, to allow it to develop the full tensile strength of the wood that it connects.

SCC See Self-consolidating concrete.

SCOF See Static Coefficient of Friction.

Scratch coat The first of two base-coat plaster applications in a three-coat plaster.

Screed A strip of wood, metal, or plaster that establishes the level to which concrete or plaster will be placed.

Screw port A three-quarter circular profile in an aluminum extrusion, made to accept a screw driven parallel to the long axis of the extrusion.

Screw slot A serrated slot profile in an aluminum extrusion, made to accept screws driven at right angles to the long axis of the extrusion.

Scupper An opening through a parapet through which water can drain over the edge of a flat roof.

Sealant A rubberlike, adhesive material, usually applied in liquid or tape form, used to seal a joint, gap, or crack against the passage of air and moisture.

Sealant gun A tool for injecting sealant into a joint.

Sealer A coating used to close the pores in a surface, usually in preparation for the application of a finish coating.

Seasoning The drying of wood, to bring its moisture content into equilibrium with ambient conditions.

Seated connection A connection in which a steel beam rests on top of a steel angle or tee that is fastened to a column or girder.

Section An architectural drawing representing a vertically cut plane through a whole building, part of a building, or detail.

Security glass A glazing sheet with multiple laminations of glass and plastic, designed to stop bullets.

Sedimentary rock Rock formed from materials deposited as sediments, such as sand or sea shells, which form sandstone and limestone, respectively.

Segregation Separation of the constituents of wet concrete caused by excessive handling or vibration.

Seismic Relating to earthquakes.

Seismic load A force on a structure caused by movement of the earth relative to the structure during an earthquake.

Seismic separation joint A building separation joint that allows adjacent building masses to oscillate independently during an earthquake.

Self-adhered flashing A flexible, self-sticking flashing material, usually made of polymer-modified asphalt laminated to a plastic backing, with preapplied adhesive on one side.

Self-consolidating concrete (SCC) Concrete formulated so that it is highly flowable and fills formwork completely without needing consolidation.

Self-consolidating grout Grout formulated so that it is highly flowable.

Self-drilling Drills its own hole.

Self-furring metal lath Metal lath with dimples that space the lath away from the sheathing behind to allow plaster to penetrate the lath and key to it.

Self-tapping Creates its own screw threads on the inside of the hole.

Self-weight The weight of a beam or slab.

Semirigid connection A partially restrained moment connection.

Sequential construction A method of providing design and construction services in which each major phase of design and construction is completed before the next phase is begun.

Set To cure; to install; to recess the heads of nails; a punch for recessing the heads of nails.

Setting block A small block of synthetic rubber or lead used to support the weight of a sheet of glass at its lower edge.

Settlement joint A building separation joint that allows the foundations of adjacent building masses to settle at different rates.

SFRM See Spray-applied fire-resistive material.

SGPL See Structural-grade plastic lumber.

Shading coefficient The ratio of total solar heat passing through a given sheet of glass to that passing through a sheet of clear double-strength glass; mostly replaced in contemporary energy calculations by solar heat gain coefficient.

Shaft An unbroken vertical passage through a multistory building, used for elevators, wiring, plumbing, ductwork, and so on.

Shaft wall A wall surrounding a shaft.

Shake A shingle split from a block of wood.

Shake-on hardener A dry powder that is dusted onto the surface of a concrete slab before troweling to react with the concrete and produce a hard wearing surface for industrial use.

Shale A rock formed from the consolidation of clay or silt.

Shallow foundation A building foundation located at the base of a wall or a column, bearing on soil relatively close to the ground surface.

Shear A deformation in which planes of material slide with respect to one another.

Shear connection A connection designed to resist only the tendency of one member to slide past the other, and not, as in a moment connection, to resist any tendency of the members to rotate with respect to one another; in steel frame construction, a simple connection.

Shear panel A wall, floor, or roof surface that acts as a deep beam to help stabilize a building against deformation by lateral forces.

Shear stud A piece of steel welded to the top of a steel beam or girder so as to become embedded in the concrete fill over the beam and cause the beam and the concrete to act as a single structural unit.

Shear wall A stiff wall that imparts lateral force resistance to a building frame.

Sheathing The rough covering applied to the outside of the roof, wall, or floor framing of a structure.

Shed A building or dormer with a single-pitched roof.

Sheeting A stiff material used to retain the soil around an excavation; a material such as polyethylene in the form of very thin, flexible sheets.

Sheet metal Flat rolled metal generally less than ¼ inch (6.35 mm) thick.

Shelf angle A horizontal steel angle attached to the wall or spandrel of a building to support a masonry facing.

SHGC See Solar heat gain coefficient.

Shim A thin piece of material placed between two components of a building to adjust their relative positions as they are assembled; to insert shims.

Shingle A small unit of water-resistant material nailed in overlapping fashion with many other such units to render a wall or sloping roof watertight; to apply shingles.

Shiplap A board with edges rabbeted so as to overlap flush from one board to the next.

Shop drawings Detailed drawings prepared by a fabricator to guide the shop production of such building components as cut stonework, steel or precast concrete framing, curtain wall panels, and cabinetwork.

Shoring Temporary vertical or sloping supports of steel or timber.

Shotcrete A low-slump concrete mixture that is deposited by being blown from a nozzle at high speed with a stream of compressed air; pneumatically placed concrete.

Shrinkage-compensating cement Specially formulated cement, used to counteract the drying shrinkage that normally occurs during curing.

Shrinkage-reducing admixture A concrete additive that reduces drying shrinkage and the cracking that results.

Shrinkage–temperature steel Reinforcing bars laid at right angles to the principal bars in a one-way slab for the purpose of preventing excessive cracking caused by drying shrinkage or temperature stresses in the concrete.

Side-hinged inswinging window A window that opens by pivoting inward on hinges at or near a vertical edge of the sash.

Side jamb See Jamb.

Sidelight A tall, narrow window alongside a door.

Siding The exterior wall finish material applied to a light frame structure.

Siding nail A nail with a small head, used to fasten siding to a building.

Silica fume Very finely divided silicon dioxide, a pozzolan, used as an admixture in the formulation of high-strength, low-permeability concrete; also called microsilica.

Silicone A polymer used for high-range sealants, roof membranes, and masonry water repellents.

Sill The horizontal bottom portion of a window or door; the exterior surface, usually sloped to shed water, below the bottom of a window or door.

Sill plate The strip of wood that lies immediately on top of a concrete or masonry foundation in wood frame construction.

Sill sealer A compressible material placed between a foundation and a sill to reduce air infiltration between the outdoors and indoors.

Simple caulk and seal A method similar to the airtight drywall approach for constructing a light frame building enclosure that is resistant to the free flow of air, but requiring less coordination between framing and sealing operations than the airtight drywall approach.

Simple connection A steel frame shear connection with no useable resistance to rotation; previously referred to as an “AISC Type 2” connection.

Single-hung window A window with two overlapping sashes, the lower of which can slide vertically in tracks and the upper of which is fixed.

Single-ply roof membrane A sheet of plastic or synthetic rubber used as a membrane for a low-slope roof.

Single-strength glass Glass approximately inch (2.5 mm) thick.

Single tee A precast slab element whose profile resembles the letter T.

SIP See Structural insulated panel.

Sitecast Concrete that is poured and cured in its final position in a building; cast in place.

Skip-joist system See Wide-module concrete joist system.

Skylight A glazed unit installed in a roof; also referred to as a unit skylight.

Slab band A very broad, shallow beam used with a one-way solid slab.

Slab on grade A concrete surface lying upon, and supported directly by, the ground beneath.

Slag The mineral waste that rises to the top of molten iron or steel or to the top of a weld.

Slag cement See Blast furnace slag.

Slaked lime See Hydrated lime.

Slate A metamorphic form of clay, easily split into thin sheets.

Sliding window A window with one fixed sash and another that moves horizontally in tracks.

Slip-critical connection A structural steel connection in which the members are clamped together by high-strength bolts with sufficient force that the loads on the members are transmitted between them by friction along their mating (faying) surfaces; also called a friction connection.

Slip forming Building multistory sitecast concrete walls with forms that rise up the wall as construction progresses.

Slip sheet A thin sheet of paper, plastic, or felt, placed between two materials to eliminate friction or bonding of the materials.

Slurry A watery mixture of insoluble materials with a high concentration of suspended solids.

Sloped glazing A system of metal and glass components used to make an inclined, transparent roof; in the International Building Code, glass sloped more than 15 degrees from vertical.

Slump test A test in which wet concrete or plaster is placed in a cone-shaped metal mold of specified dimensions and allowed to sag under its own weight after the cone is removed. The vertical distance between the height of the mold and the height of the slumped mixture is an index of its working consistency.

Slurry A watery mixture of insoluble materials with a high concentration of suspended solids.

Smoke-developed rating An index of the toxic fumes generated by a material as it burns, as determined by ASTM standard E84.

Smoke shelf The horizontal area behind the damper of a fireplace.

Slow-burn construction See Mill construction.

Sodium borate (SBX) A chemical used to preserve wood against attack by decay and insects.

Soffit The undersurface of a horizontal element of a building, especially the underside of a stair or a roof overhang.

Soffit vent An opening under the eave of a roof used to allow air to flow into the attic or the space below the roof sheathing.

Soft mud process Making bricks by pressing wet clay into molds.

Softwood Wood from coniferous (evergreen) trees.

Soil Any particulate earth material, excluding rock.

Solar heat gain coefficient (SHGC) The ratio of solar heat admitted through a particular glass to the total heat energy striking the glass.

Solar reflectance A unitless index, ranging from 0 to 1, expressing a material's tendency to absorb or reflect solar radiation; also called albedo.

Soldering A low-temperature form of brazing.

Soldier A brick laid on its end, with its narrow face toward the outside of the wall.

Sole plate The horizontal piece of dimension lumber at the bottom of the studs in a wall in a light frame building; also called a bottom plate.

Solid-core door A flush door with no internal cavities.

Solid masonry Masonry walls without cavities; historically, thick, monolithic masonry walls that rely primarily on their mass for their strength, durability, and tempering of the flow of heat and moisture from inside to outside.

Solid slab A concrete slab, without ribs or voids, that spans between beams or bearing walls.

Solid tape sealant See Preformed solid tape sealant.

Solvent A liquid that dissolves another material.

Sound Transmission Class (STC) An index of the resistance of a wall or partition to the passage of sound.

Space truss, space frame A truss that spans with two-way action.

Spalling The cracking or flaking of the surface of concrete or masonry units, caused, for example, by freeze-thaw action, corroding reinforcing, or pointing mortars that are harder and stronger than the mortar deeper in the masonry joint.

Span The distance between supports for a beam, girder, truss, vault, arch, or other horizontal structural device; to carry a load between supports.

Spandrel The wall area between the head of a window on one story and the sill of a window on the floor above; the area of a wall between adjacent arches.

Spandrel beam A beam that runs along the outside edge of a floor or roof.

Spandrel glass Opaque glass manufactured especially for use in spandrel panels.

Spandrel panel A curtain wall panel used in a spandrel.

Span rating The number stamped on a sheet of plywood or other wood building panel to indicate how far in inches it may span between supports.

Specifications The written instructions from an architect or engineer concerning the quality of materials and execution required for a building.

Spirit level A tool in which a bubble in an upwardly curving cylindrical glass vial indicates whether a building element is level or not level, plumb or not plumb.

Splash block A small precast block of concrete or plastic used to divert water at the bottom of a downspout.

Spline A thin strip inserted into grooves in two mating pieces of material to hold them in alignment; a ridge or strip of material intended to lock to a mating groove. In glazing, the edge spacer in an insulating glass unit.

Split jamb A door frame fabricated in two interlocking halves, to be installed from the opposite sides of an opening.

Spray-applied fire-resistive material (SFRM) Fibrous or cementitious insulation applied to steel or concrete with a sprayer to provide protection against the heat of fire.

Springwood In wood, the portion of the growth ring comprised of relatively larger, less dense cells; also called earlywood.

SSP See Stressed-skin panel.

Staggered truss system A steel framing system in which story-high trusses, staggered one-half bay from one story to the next, support floor decks on both their top and bottom chords.

Stain A coating intended primarily to change the color of wood or concrete without forming an impervious film.

Stainless steel A steel alloy, silvery in color, with superior corrosion resistance due principally to high chromium and nickel content.

Standing and running trim Door and window casings and baseboards.

Standing seam A sheet metal roofing seam that projects at right angles to the plane of the roof.

Static Coefficient of Friction (SCOF) A measure of the slip resistance of a flooring material.

Stay A sloping cable used to stabilize a structure.

STC See Sound Transmission Class.

Steam curing Aiding and accelerating the setting reaction of concrete by the application of steam.

Steel Iron with a controlled amount of carbon, generally less than 2 percent.

Steel reinforcing bars Hot-rolled, deformed steel bars used to impart tensile strength and ductility to concrete structures; rebar.

Steel trowel A metal bladed tool used in the final stages of finishing of a concrete slab.

Steep roof A roof with sufficient slope to be made waterproof with shingles. In the International Building Code, a roof with a slope of 2:12 (17 percent) or greater.

Sticking The cementing together of defects in marble slabs.

Stick system A metal curtain wall system that is largely assembled in place.

Stiffener plate A steel plate attached to a structural member to support it against heavy localized loading or stresses.

Stiff mud process A method of molding bricks in which a column of damp clay is extruded from a rectangular die and cut into bricks by fine wires.

Stile A vertical framing member in a panel door.

Stirrup A vertical loop of steel bar used to reinforce a concrete beam against diagonal tension forces.

Stirrup-tie A stirrup that forms a complete loop, as differentiated from a U-stirrup, which has an open top.

Stool The interior horizontal plane at the sill of a window.

Storm window A sash added to the outside of a window in winter to increase its thermal resistance and decrease air infiltration.

Story pole A strip of wood marked with the exact course heights of masonry for a particular building, used to make sure that all the leads are identical in height and coursing.

Straightedge To strike off the surface of a concrete slab using screeds and a straight piece of lumber or metal; as a noun, a long, straight item, used to perform straightedging, test the flatness of a surface, or trace a straight line.

Strain Deformation under stress; expressed as a ratio of the change in length over the original length.

Stress Force per unit area.

Stressed-skin panel (SSP) A panel consisting of two face sheets of wood, metal, or concrete bonded to perpendicular spacer ribs or framing members such that the panel can act as a composite structural panel.

Stretcher A brick or masonry unit laid in its most usual position, with the broadest surface of the unit horizontal and the length of the unit parallel to the surface of the wall.

Striated Textured with parallel scratches or grooves.

Stringer The sloping wood or steel member that supports the treads of a stair.

Strip flooring Solid wood finish flooring members less than 3 inches (75 mm) in width, usually in the form of tongue-and-groove boards.

Stripping Removing formwork from concrete; sealing around a roof flashing with layers of felt and bitumen.

Structural bond The interlocking pattern of masonry units used to tie two or more wythes together in a wall.

Structural composite lumber Substitutes for solid lumber made from wood veneers or wood fiber strands and glue; also called engineered lumber.

Structural glazed facing tile A hollow clay masonry unit with glazed faces.

Structural-grade plastic lumber (SGPL) Lumberlike plastic members, reinforced with glass fibers, and formulated to be roughly as strong as conventional solid wood.

Structural insulated panel (SIP) A panel consisting of two face sheets of wood panel bonded together by plastic foam core.

Structural lightweight aggregate Lightweight aggregate with sufficient density and strength for use in structural concrete.

Structural mill The portion of a steel mill that rolls structural shapes.

Structural silicone flush glazing Glass secured to the face of a building with strong, highly adhesive silicone sealant to eliminate the need for any metal to appear on the exterior of the building.

Structural standing-seam metal roofing Sheets of folded metal that serve both as decking and as the waterproof layer of a roof.

Structural terra cotta Molded components, often highly ornamental, made of fired clay, designed to be used in the facades of buildings.

Structural tubing See Hollow structural section.

Structure/enclosure joint A connection designed to allow the structure of a building and its cladding or partitions to move independently.

Stucco Plaster made from a mixture of portland cement, lime, sand, and water; commonly used as an exterior finish material.

Stud One of an array of small, closely spaced, parallel wall framing members; a heavy steel pin.

Styrene-butadiene-styrene (SBS) A copolymer of butadiene and styrene used as a modifier in polymer-modified bitumen roofing.

Subcontractor A contractor who specializes in one area of construction activity and who works under a general contractor.

Subfloor The loadbearing surface beneath a finish floor.

Subpurlin A very small roof framing member that spans between joists or purlins.

Substrate The base to which a coating, veneer, or finish material is applied.

Substructure The occupied below-ground portion of a building.

Summerwood In wood, the portion of the growth ring comprised of relatively smaller, denser cells; also called latewood.

Sump A pit designed to collect water for removal from an excavation or basement.

Superflat floor A concrete slab finished to a high degree of flatness and levelness according to a recognized system of measurement.

Superplasticizer An admixture that makes wet concrete or grout extremely fluid without additional water.

Superstructure The above-ground portion of a building.

Supplementary cementitious material Hydraulic cementitious material or poz-zolan mixed with portland cement to modify the cement product's properties or lower the energy required to manufacture the cement.

Supply pipe A pipe that brings clean water to a plumbing fixture.

Supporting stud A wall framing member that extends from the sole plate to the underside of a header and supports the header.

Surface-bonded masonry Concrete block laid without mortar and then plastered on both sides with a fiber-reinforced cement plaster so as to make a structurally sound masonry wall.

Surfacing Smoothing the surface of a material, usually by planing.

Surface divider joint A line along which a surface may expand and/or contract without damage.

Surface number In glazing assemblies, the distinct faces of glazing, counting from the outermost to the innermost of a glazing unit, including each face of each glazing material.

Suspended ceiling A finish ceiling that is hung on wires from the structure above.

Suspended glazing Large sheets of glass hung from clamps at their top edges to eliminate the need for metal mullions.

Sustainability Providing for the needs of the current generation without compromising the ability of future generations to provide for their needs. Providing healthy, resource- conserving, energy-efficient buildings. “Green” building.

Swedge bolt See lockpin and collar fastener.

Synthetic gypsum Chemically manufactured gypsum made from the byproducts of various industrial processes, such as the desulfurization of power plant flue gasses.

T

Tackstrip See Tackless strip.

Tackless strip A wood strip with projecting points used to fasten a carpet around the edge of a room; also called a tackstrip.

Tagline A rope attached to a building component to help guide it as it is lifted by a crane or derrick.

Tap To cut internal threads, such as in a hole or nut.

Tangential shrinkage In wood, shrinkage along the circumference of the log.

Tapered edge The longitudinal edge of a sheet of gypsum board, which is recessed to allow room for reinforcing tape and joint compound.

Tee A metal or precast concrete member with a cross section resembling the letter T.

Tempered glass Heat-treated glass that is stronger than heat-strengthened glass and is suitable for use as safety glazing.

Tempering Controlled heating and cooling of a material to alter its mechanical properties; a form of heat-treatment.

Tendon A steel strand used for prestressing a concrete member.

Tensile strength The ability of a structural material to withstand stretching forces.

Tensile stress A stress caused by stretching of a material.

Tension A stretching force; to stretch.

Tension control bolt A bolt tightened by means of a splined end that breaks off when the bolt shank has reached the required tension.

Termite shield A metal flashing placed on top of a concrete foundation to prevent termites from traveling undetected from the ground into the superstructure.

Terne An alloy of lead and tin, used to coat sheets of carbon steel or stainless steel, used in the past for metal roofing sheet.

Terrace door A double glass door, one leaf of which is fixed and the other hinged to the fixed leaf at the centerline of the door.

Terrazzo A finish floor material consisting of concrete with an aggregate of marble chips selected for size and color, which is ground and polished smooth after curing.

Thatch A thick roof covering of reeds, straw, grasses, or leaves.

Thermal break A section of material with low thermal conductivity installed between metal components to retard the passage of heat through a wall or window assembly.

Thermal bridge A component of higher thermal conductivity that conducts heat more rapidly through an insulated building assembly, such as a steel stud in an insulated stud wall.

Thermal conductivity The rate at which a material conducts heat.

Thermal emittance A unitless index, from 0 to 1, expressing a material's tendency to radiate thermal energy as its temperature rises in relation to surrounding surfaces.

Thermal envelope See Building enclosure.

Thermal insulation A material that greatly retards the passage of heat.

Thermal resistance The resistance of a material or assembly to the conduction of heat.

Thermochromic glass Glass that changes its optical properties in response to changes in temperature.

Thermoplastic In plastics, having the property of softening when heated and rehardening when cooled; weldable by heat or solvents.

Thermoplastic polyolefin (TPO) A thermoplastic single-ply roof membrane material, made from blends of polyethylene, polypropylene, and ethylene-propylene rubber polymers.

Thermosetting In plastics, not having the property of softening when heated; not heat-fusible.

Thickset tile Ceramic tile installed on a thick bed of portland cement mortar; also called mortar bed or mud set tile.

Thin-set tile Ceramic tile bonded to a solid base with a thin application of portland cement mortar or organic adhesive.

Through-wall flashing See Internal flashing.

Thrust A lateral or inclined force resulting from the structural action of an arch, vault, dome, suspension structure, or rigid frame.

Thrust block A wooden block running perpendicular to the stringers at the bottom of a stair, whose function is to hold the stringers in place.

Tie A device for holding two parts of a construction together; a structural device that acts in tension.

Tieback A tie, one end of which is anchored in the ground, with the other end used to support sheeting around an excavation.

Tie beam A reinforced concrete beam cast as part of a masonry wall, whose primary purpose is to hold the wall together, especially against seismic loads, or cast between a number of isolated foundation elements to maintain their relative positions.

Tier The portion of a multistory steel building frame supported by one set of fabricated column pieces, commonly two stories in height.

Tie rod A steel rod that acts in tension.

Tile A fired clay product that is thinner in cross section than a brick, either a thin, flat element (ceramic tile or quarry tile), a thin, curved element (roofing tile), or a hollow element with thin walls (flue tile, tile pipe, structural clay tile); also a thin, flat element of another material, such as an acoustical ceiling unit or a resilient floor unit.

Tilt/turn window A window that opens either by rotating its sash about its vertical centerline or as a hopper.

Tilt-up construction A method of constructing concrete walls in which panels are cast and cured flat on a floor slab, then tilted up into their final positions.

Timber Standing trees; a large piece of dimension lumber.

Tinted glass Glass that is colored with pigments, dyes, or other admixtures.

Titanium A strong, corrosion-resistant, nonferrous metal, silver gray in color.

Toe nailing Fastening with nails driven at an angle.

Tongue and groove An interlocking edge detail for joining planks or panels.

Tooling The finishing of a mortar joint or sealant joint by pressing and compacting it to create a particular profile.

Toothed plate A multipronged fastener made from stamped sheet metal, used to join members of a lightwood wood truss.

Top-hinged inswinging window A window that opens inward on hinges on or near its head.

Topping A thin layer of concrete cast over the top of a floor deck.

Topping-out Placing the last member in a building frame.

Top plate The horizontal member at the top of the studs in a wall in a light frame building.

Topside vent A water-protected opening through a roof membrane to relieve pressure from water vapor that may accumulate beneath the membrane.

Torque Twisting action; moment.

Torsional stress Stress resulting from the twisting of a structural member.

Touch sanded In plywood, lightly sanded to produce a smoother, flatter surface.

TPO see Thermoplastic polyolefin.

Tracheids The longitudinal cells in a softwood.

Traffic deck A walking surface placed on top of a roof membrane.

Transit-mixed concrete Concrete mixed in a drum on the back of a truck as it is transported to the building site.

Travertine A richly patterned, marblelike form of limestone; classified by ASTM C119 in the Other Stone group.

Tread One of the horizontal planes that make up a stair.

Tremie A large funnel with a tube attached, used to deposit concrete in deep forms or beneath water or slurry.

Trim accessories Casing beads, corner beads, expansion joints, and other devices used to finish edges and corners of a plaster wall or ceiling.

Trimmer joist A joist that supports a header around an opening in a floor or roof frame.

Trimmer stud. See Jack stud

Trowel A thin, flat steel tool, either pointed or rectangular, provided with a handle and held in the hand, used to manipulate mastic, mortar, plaster, or concrete. Also, a machine whose rotating steel blades are used to finish concrete slabs; to use a trowel.

Truss A triangulated arrangement of structural members that reduces nonaxial external forces to a set of axial forces in its members. See also Vierendeel truss.

Tuckpointing Traditionally, a method of finishing masonry joints using mortars of different colors to artificially create the appearance of a more refined joint; in contemporary usage, may be used interchangeably with repointing.

Tunnel kiln A kiln through which clay products are passed on railroad cars.

Turn-of-nut method A method of achieving the correct tightness in a high-strength bolt by first tightening the nut snugly, then turning it a specified additional fraction of a turn.

Two-way action Bending of a slab or deck in which bending stresses are approximately equal in the two principal directions of the structure.

Two-way concrete joist system A reinforced concrete framing system in which columns directly support an orthogonal grid of intersecting joists.

Two-way flat plate A reinforced concrete framing system in which columns directly support a two-way slab that is planar on both of its surfaces.

Two-way flat slab A reinforced concrete framing system in which columns with mushroom capitals and/or drop panels directly support a two-way slab that is planar on both of its surfaces.

Type IV HT construction See Heavy timber construction.

Type X gypsum board A fiber-reinforced gypsum board used where greater fire resistance is required.

U

U-Factor A measure of the thermal conductance of a material or assembly; the mathematical reciprocal of R-value.

Unbonded construction Posttensioned concrete construction in which the tendons are not grouted to the surrounding concrete.

Uncoursed stone masonry Stone masonry laid without continuous horizontal joints; random.

Undercarpet wiring system Flat, insulated electrical conductors that run under carpeting, and their associated outlet boxes and fixtures.

Undercourse A course of shingles laid beneath an exposed course of shingles at the lower edge of a wall or roof in order to provide a waterproof layer behind the joints in the exposed course.

Underfire The floor of the firebox in a fireplace.

Underlayment A panel laid over a subfloor to create a smooth, stiff surface for the application of finish flooring. Or, a water-resistant material applied under shingled roofing.

Underpinning The process of placing new foundations beneath an existing structure.

Unfinished bolt An ordinary carbon steel bolt.

Uniformly graded soil A special instance of a well-sorted soil in which the soil particles are mostly of one size.

Uniform settlement Subsidence of the various foundation elements of a building at the same rate, resulting in no distress to the structure of the building.

Unit-and-mullion system A curtain wall system consisting of prefabricated panel units secured with site-applied mullions.

Unit skylight See Skylight.

Unit system A curtain wall system consisting entirely of prefabricated panel units.

Unreinforced Constructed without steel reinforcing bars or welded wire fabric.

Up–down construction A sequence of construction activity in which construction proceeds downward on the sublevels of a building at the same time as it proceeds upward on the superstructure.

Upside-down roof A membrane roof assembly in which the thermal insulation lies above the membrane.

U-stirrup An open-top, U-shaped loop of steel bar used as reinforcing against diagonal tension in a concrete beam.

V

Valley A trough formed by the intersection of two roof slopes.

Valley rafter A diagonal rafter that supports a valley.

Vapor barrier See Vapor retarder.

Vapor permeability Vapor permeance per unit of thickness.

Vapor permeance A measure of the ease with which water vapor can diffuse through a material.

Vapor pressure A measure of the pressure exerted by water molecules in a gaseous state, generally higher with higher relative humidity and higher air temperature.

Vapor retarder A layer of material intended to resist the diffusion of water vapor through a building assembly. Also called, less accurately, vapor barrier.

Varnish A slow-drying transparent coating.

Vault An arched surface. A strongly built room for such purposes as housing large electrical equipment or safeguarding money.

Vee joint A joint whose profile resembles the letter V.

Vegetated roof See Green roof.

Veneer A thin layer, sheet, or facing.

Veneer plaster A wall finish system in which a thin finish layer of gypsum plaster is applied over a special gypsum board base.

Veneer plaster base The special gypsum board over which veneer plaster is applied.

Vent spacer A device used to maintain a free air passage above the thermal insulation in an attic or roof.

Vermiculite Expanded mica, used as an insulating fill or lightweight aggregate.

Vertical bar An upright reinforcing bar in a concrete column; also called a column bar.

Vertical grain lumber Dimension lumber sawed in such a way that the annual rings run mostly perpendicular to the faces of each piece; also called edge-grain lumber. See also Flat-grain lumber.

Vierendeel truss A truss with rectangular panels and rigid joints but no diagonal members. The members of a Vierendeel truss are subjected to strong nonaxial forces.

Vinyl See Polyvinyl chloride.

Visible light transmittance (VT) The ratio of visible light that passes through a sheet of glass or a glazing unit to the amount of light striking the glass or unit.

Visual grading The grading of wood for its structural properties, based on visual inspection, as distinct from machine grading; not to be confused with appearance grading.

Vitrification The process of transforming a material into a glassy substance by means of heat.

Volatile organic compound (VOC) Organic (carbon-based) chemical compound that evaporates readily, is a significant air pollutant, a potential irritant to building occupants, and, in some cases, a greenhouse gas.

Volume change joint A building separation joint that allows for expansion and contraction of adjacent portions of a building without distress.

Voussoir A wedge-shaped element of an arch or vault.

VT See Visible light transmittance.

W

Waferboard A building panel made by bonding together large, flat flakes of wood.

Waffle slab A two-way concrete joist system.

Wainscoting A wall facing, usually of wood, cut stone, or ceramic tile, that is carried only partway up a wall.

Waler A horizontal beam used to support sheeting or concrete formwork.

Wane An irregular rounding of a long edge of a piece of dimension lumber caused by cutting the lumber from too near the outside surface of the log.

Warm edge spacer A glazing edge spacer with improved thermal resistance.

Washer A steel disk with a hole in the middle, used to spread the load from a bolt, screw, or nail across a wider area of material.

Water–cement ratio An expression of the relative proportions, by weight, of water and cement in a concrete mixture.

Waterproofing Material acting as a barrier to the flow of water and capable of withstanding hydrostatic pressure.

Water-reducing admixture Concrete admixture that allows a reduction in the amount of mixing water while retaining the same workability, resulting in higher-strength concrete.

Water-resistant gypsum board A gypsum board designed for use in locations where it may be exposed to occasional dampness.

Water smoking The process of applying heat to evaporate the last water from clay products before they are fired.

Waterstop A metal, synthetic rubber, bentonite clay, or sealant strip used to seal joints in concrete foundation walls.

Water-struck brick A brick made in a mold that was wetted before the clay was placed on it.

Water table The level at which the pressure of water in the soil is equal to the atmospheric pressure; effectively, the level to which groundwater will fill an excavation; a wood molding or shaped brick used to make a transition between a thicker foundation and the wall above.

Water vapor Water in its gaseous phase.

Wattle and daub Mud plaster (daub) applied to a primitive lath of woven twigs or reeds (wattle).

Waxing Filling of voids in marble slabs.

Weathered joint A mortar joint finished in a sloping, planar profile that tends to shed water to the outside of the wall.

Weathering steel A steel alloy that forms a tenacious, self-protecting rust layer when exposed to the atmosphere.

Weather-resistive barrier A membrane used to resist the passage of liquid water or air through the exterior enclosure of a building.

Weatherstrip A ribbon of resilient, brushlike, or springy material used to reduce air infiltration through the crack around a sash or door.

Web A cross-connecting piece, such as the portion of a wide-flange shape that is perpendicular to the flanges or the portion of a concrete masonry unit that is perpendicular to the face shells.

Web stiffener A metal rib used to support the web of a light gauge steel joist or a structural steel girder against buckling.

Weep hole A small opening whose purpose is to permit drainage of water that accumulates inside a building component or assembly.

Weld A joint between two pieces of metal formed by fusing the pieces together by the application of intense heat, usually with the aid of additional metal melted from a rod or electrode.

Welded wire fabric (WWF) See Welded wire reinforcing.

Welded wire reinforcing (WWR) A welded grid of steel reinforcing wires or bars, used most commonly for reinforcing of slabs; also called welded wire fabric (WWF).

Welding The process of making a weld.

Weld plate A steel plate anchored into the surface of concrete, to which another steel element can be welded.

Well-graded soil Coarse-grained soil with a full range of particle sizes; also called poorly sorted soil.

Well-sorted soil Soil with less than a full range of particle sizes; also called poorly graded soil.

“Wet” systems Construction systems that utilize considerable quantities of water on the construction site, such as masonry, plaster, sitecast concrete, and terrazzo.

White portland cement A portland cement that is white in color; used for architectural concrete where greater color control is required.

Wide-flange shape Any of a wide range of structural steel components rolled in the shape of the letter I or H.

Wide-module concrete joist system A one-way concrete framing system with joists that are spaced more widely than those in a conventional one-way concrete joist system.

Wind brace A diagonal structural member whose function is to stabilize a frame against lateral forces.

Winder (rhymes with “reminder”) A stair tread that is wider at one end than at the other.

Wind load A force on a building caused by wind pressure and/or suction.

Wind uplift Upward forces on a structure caused by negative aerodynamic pressures that result from certain wind conditions.

Wired glass Glass in which a wire mesh is embedded during manufacture, principally for fire resistance.

Wood-plastic composites (WPC) Wood-like products made from wood fibers, plastics of various types, and other additives, with a plastic content not exceeding 50 percent

Wood–polymer composite planks Linear strips intended for outdoor decking and other outdoor uses that are made of wood fiber and a plastic binder.

Workability agent Admixture for concrete that improves the plasticity of wet material to make it easier to place in forms and to finish.

Working construction joint A connection that is designed to allow for small amounts of relative movement between two pieces of a building assembly.

WPC See Wood-plastic composites.

Wracking Forcing out of plumb.

Wrought iron A form of iron that is soft, tough, and fibrous in structure, containing about 0.1 percent carbon and 1–2 percent slag.

WWF See Welded wire fabric.

WWR See Welded wire reinforcing.

Wythe (rhymes with “scythe” and “tithe”) A vertical layer of masonry that is one masonry unit thick.

Y

Yield strength The stress at which a material ceases to deform in a fully elastic manner and begins to deform irreversibly.

Z

Z-brace door A door made of vertical planks held together and braced on the back by three pieces of wood whose configuration resembles the letter Z.

Zero-slump concrete A concrete mixed with so little water that it does not sag when piled vertically.

Zinc A relatively weak and brittle nonferrous metal used, most notably, as a protective galvanic coating for steel.

Zoning ordinance A law that specifies in detail how land within a municipality may be used.