Now that you have created all the building components that will be in the floor plan, it's a good time to draw the exterior elevations. Elevations are horizontal views of a building, seen as if you were standing facing the building instead of looking down at it, as you do with a floor plan. An elevation view shows you how windows and doors fit into the walls and gives you an idea of how the building will look from the outside. In most architectural design projects, the drawings include at least four exterior elevations: front, back, and one for each side.
I'll go over how to create the south elevation first. Then I'll discuss some of the considerations necessary to complete the other elevations, and you'll have an opportunity to draw them on your own.
In mechanical drawing, the item being drawn is often a machine part or a fixture. The drafter uses orthographic projection—a method for illustrating an object in views set at right angles to each other: front, top, side, back, and so on—instead of elevations and plans. An exercise later in this chapter will give you practice with orthographic projection, but the procedure will be the same whether you're drawing buildings or mechanical objects.
The first elevation view you'll create is the south view. This will reflect the appearance of the cabin as if you were looking at it from the side with the bath and living room windows. Before starting on these elevation views, however, you'll need to create some additional layers. These layers will mimic many of the layers already in your drawing but will use the major ELEV code to distinguish them from the layers used for your floor plan.
Open the Layer Properties Manager palette from the Home tab Layers panel.
Using the New Layer button, create the layers with the properties shown in the following table.
You draw the elevation by using techniques similar to those used on a traditional drafting board. You'll draw the south elevation view of the cabin directly below the floor plan by dropping lines down from key points on the floor plan and intersecting them with horizontal lines representing the heights of the corresponding components in the elevation. Figure 10.1 shows those heights. For this project, we'll consider the top of the screen to be north.
Follow these steps:
The line you offset establishes a baseline to represent the ground or the bottom of the cabin. You can now offset the other height lines from the baseline or from other height lines:
A soffit is the under-side of the roof over-hang that extends from the outside edge of the roof back to the wall.
The lines should look like those shown in Figure 10.4.
These will be the lines at the edge of the roof, where it covers the pop-out (see Figure 10.5). Note that two of the lines appear to be at the same height. Use a crossing selection window to select the lines; be sure not to select the line representing the tops of the windows.
Each of these lines represents the height of one or more components of the cabin. Now you'll drop lines down from the points in the floor plan that coincide with components that will be visible in the elevation. The south elevation will consist of the exterior walls, two windows, the pop-out, and the roof.
As you know, to create a standard line, you must define both a starting and ending point for the line. In addition to the standard LINE command, however, the Autodesk® AutoCAD® software offers two additional types of lines: rays and construction lines.
Rays Rays are a mix between standard and construction lines. Rays have a starting point but no end point.
Construction Lines Construction lines have neither a starting nor an ending point, and they extend to infinity in both directions.
Both rays and construction lines can be trimmed in much the same way as standard lines. Because, by definition, a construction line is a line of infinite length, trimming it will force it to extend to infinity in one direction. Consequently, using the TRIM command on a construction line will, at a minimum, turn it into a ray. Similarly, using the TRIM command on a ray will define an endpoint, consequently reducing it to a standard AutoCAD line.
You'll use construction lines to project key points from your floor plan to the area within the drawing where you will draw your south elevation. As you do this, pay attention to the way construction lines are reduced into rays, and rays into standard lines.
Start the XLINE (Construction Line) command from the expanded Draw panel on the Home tab.
With the Vertical option, the XLINE command will create a vertical line extending to your south elevation and beyond at each point you select.
Construction lines, like most other objects in AutoCAD, have a number of grips. Selecting the construction line you just drew will make three grips (blue boxes) appear. Grips can be used to modify objects in your drawing quickly and easily.
Among the possible operations using grips is the Copy function. You'll create the remaining projection points using this method:
Three grips appear along the construction line: one at the insertion point and two more above and below it (see Figure 10.7).
The STRETCH command is a modifying tool that you use to lengthen or shorten lines and other objects. You'll have another chance to use it in Chapter 11, “Working with Hatches, Gradients, and Tool Palettes.”
The grip changes color from blue to red, and the prompt changes to Specify stretch point or [Base point/Copy/Undo/eXit]:. This is the STRETCH command. Any time you activate a grip, the STRETCH command automatically starts.
This starts the COPY command, using the selected grip as the first point.
Every command that works with grips has a Copy option, which keeps the original object “as is” while you modify the copy. You can copy with grips in ways not possible with the COPY command.
The construction line is copied to each of these corners and extends down to where you'll draw the south elevation.
In the next section, you'll trim the lines as necessary to continue the elevation drawing.
GETTING A GRIP ON GRIPS
In Chapter 7, “Combining Objects into Blocks,” you saw how to use grips to detect whether an object is a block. Grips actually serve a larger function. The STRETCH command will automatically start when you select a single grip. With a single grip selected, the right-click menu offers a list of additional tools for editing objects quickly by using one or more of the following five commands: STRETCH, MOVE, ROTATE, SCALE, and MIRROR. These commands operate a little differently when using grips than when using them otherwise.
The commands can also perform a few more tasks with the help of grips. Each command has a Copy option. So, for example, if you rotate an object with grips, you can keep the original object unchanged while you make multiple copies of the object in various angles of rotation. You can't do this by using the ROTATE command in the regular way or by using the regular COPY command.
To use grips, follow these steps:
You can also cycle through these commands by pressing the spacebar and watching the command prompt.
The key to being able to use grips efficiently is in knowing which grip to select to start the process. This requires a good understanding of the five commands that work with grips.
This book doesn't cover grips in depth, but it introduces you to the basics. You'll get a chance to use the MOVE command with grips in this chapter, and you'll use grips again when you get to Chapter 12, “Dimensioning a Drawing.”
Keep the following in mind when working with grips:
1. Select a grip, and enter B.
2. Pick a different point to serve as a base point.
3. Continue the command.
The next task is to extend and trim the appropriate lines in the elevation. You'll start by extending the rooflines:
By not selecting any cutting edges, every edge in the drawing is used as a cutting edge.
The roof extends a little farther than the rest of the roof where the hot tub is located.
NOTE Notice that the extension lines are no longer construction lines. By using the TRIM command, you defined a start point for each construction line where it intersected a cutting edge. Because construction lines extend to infinity in both directions, our line is reduced to a ray. As you may recall, a ray has a start point but no endpoint.
Start the FILLET command from the Home tab Modify panel.
This completes the roof outline in your elevation view. The only thing left to do is clean up the lines defining the two windows.
From the extended Modify panel within the Home tab, choose the Break At Point tool.
The line will appear unchanged visually; however, selecting it will reveal that the line has been divided into two separate line segments.
This is the basic process for generating an elevation: drop lines down from the floor plan, and trim the lines that need to be trimmed. The trick is to learn to see the picture you want somewhere among all the crossed lines and then to be able to use the TRIM command accurately to cut away the appropriate lines.
TIPS FOR USING THE TRIM AND EXTEND COMMANDS
TRIM and EXTEND are sister commands. Here are a few tips on how they work.
Basic Operation
Both commands involve two steps: selecting cutting edges (TRIM) or boundary edges (EXTEND) and then selecting the lines to be trimmed or extended:
You can use the Fence option or a selection window to select several lines to trim or extend at one time.
Trimming and Extending in the Same Command
If you find that a cutting edge for trimming can also serve as a boundary edge for extending, hold down the Shift key and click a line to extend it to the cutting edge. The opposite is true for the EXTEND command.
Correcting Errors
It's easy to make a mistake in selecting cutting or boundary edges or in trimming and extending. You can correct a mistake in two ways:
1. Enter R, and then choose the lines again that were picked in error. They will lose their highlighting.
2. If you need to keep selecting cutting or boundary edges, enter A and select new lines.
3. When finished, press to move to the second part of the command.
1. Enter U, or right-click and choose Undo from the context menu. This undoes the last trim.
2. Click Undo again if you need to untrim or unextend more lines.
3. When you have made all the corrections, continue trimming or extending.
4. Press to end the command.
If the command ended and you click the Undo button, you will undo all trimming or extending that was done in the preceding command.
You set the A-ELEV-WALL layer as current as you began drawing your elevation view. At that point, you were mostly interested in getting the elevation's geometry in place, and not as interested in layers. With the geometry in place, now is a good time to pause for a moment and place everything on the correct layers. Currently, the exterior walls, roof, and windows are drawn. Follow these steps to assign A-ELEV-WALL, A-ELEV-ROOF, and A-ELEV-GLAZ, respectively, to those objects:
With each component of your elevation view on the proper layer, you can begin to refine the view further. Currently, the elevation view does not illustrate your deck, stairs, or foundation. Let's begin adding these components, starting with the front and rear decks.
The cabin sits on an 18″ (457 mm) foundation (which you'll add in the “Drawing the Supports and Foundation” section later in this chapter), with the surrounding land falling away from it at a slight angle. On the front and back sides are decks with stairways to step up to the door levels. In this section, you'll draw the front deck first, mirror it to the other end, and then adjust the second deck to match the conditions at the back of the cabin.
Figure 10.17 shows the dimensions required to draw the horizontal elements of the stairway, while most vertical lines are dropped from the floor plan.
Follow these steps to draw the front deck:
Make sure the line extends beyond the limits of the stairway in the floor plan.
Here you're first going to offset the horizontal line several times and then trim the resulting lines back to the lines that represent the post.
(194 mm)
(295 mm)
(1260 mm)
(1312 mm)
The right end of your elevation should look like Figure 10.19.
The railing posts are (20 mm) square components that are 3′-0″ (915 mm) long and spaced with a 4″ (102 mm) gap between each one. After the first object is drawn, you could apply strategies learned in earlier chapters to copy the remaining posts manually.
As you will see in a moment, the ARRAY command provides an efficient way to copy objects as an associative group. This associative group can be created in any one of three distinct ways: rectangular, polar, or what you'll use in this exercise—path. Using the Path Array (ARRAYPATH) command, each of the vertical railing posts will be created using only a single instance of one command. Here's how:
Because you have not yet defined any parameters for the array, the ARRAYPATH command fits a large number of vertical railings along the selected path, as shown in Figure 10.24.
The array is created using the parameters specified in the preceding procedure, and it should now match Figure 10.25.
There are four steps leading up to the cabin, each with an 8″ (204 mm) rise and a (41 mm) thick tread. The 10″ (254 mm) length of the steps, also called the run, is based on the lines dropped from the steps in the floor plan.
These lines are the tops of the stair treads.
Try using a crossing window to select multiple lines to trim at one time.
Your stairway should look like Figure 10.28.
For the stringer (the support for the steps), you need a line that matches the angle between each step.
The last parts of the stairway to draw are the 2″ (51 mm) railing posts and the handrail.
When you're finished, your deck should look like Figure 10.31.
The cabin rests on a foundation, and the decks are supported by concrete posts. You can quickly draw these by using the Rectangle (RECTANG) command with object snaps and the Object Snap Tracking tool.
Start the Rectangle (RECTANG) command, and draw a rectangle with its first point at the right end of the lowest horizontal deck line and the second point 1′ (305 mm) to the left and 2′-10″ (864 mm) below that point (in other words, at −1′,−2′-10″ or at −305,−864 mm).
The foundation rectangle is shown in Figure 10.33.
From this view, the decks, stairways, post, and supports are nearly symmetrical, making the Mirror tool an excellent choice for creating most of the objects on the back deck. The front deck is wider than the back deck, but an efficient use of the ERASE and TRIM commands can quickly fix that.
The components on the right remain ghosted, while the new components on the left appear solid, as shown in Figure 10.34.
Try enabling Selection Cycling on the status bar to help you select the line that overlaps the top of the foundation.
Your back deck should look like Figure 10.35.
WARNING Trimming the horizontal deck lines prior to adjusting the Path Array will open an Associative Path Array error dialog box. This dialog box is simply warning that your array extends beyond the length of the path (or in this case, line) that was selected when the array was created.
The full set of drawings that contractors use to construct a building includes an elevation for each side of the building. In traditional drafting by hand, the elevations were usually drawn on separate sheets. This required transferring measurements from one drawing to another by taping drawings next to each other, turning the floor plan around to orient it to each elevation, and using several other cumbersome techniques. You do it about the same way on the computer, but it's much easier to move the drawing around. You'll be more accurate, and you can quickly borrow parts from one elevation to use in another.
Because the north elevation shares components and sizes with the south elevation, you can mirror the front elevation to the rear of the building and then make the necessary changes:
Use the Pan tool, or hold down the scroll wheel, to move the view of the floor plan to the middle of the screen.
The first side elevation is mirrored to the opposite side of the cabin (see the right of Figure 10.36). You can now make the necessary changes to the new elevation so that it correctly describes the south elevation of the cabin. However, you might find it easier to work if the view is right side up.
Take a look at the icon, currently located at the origin, for a moment. The two lines in the icon show the positive X and Y directions of the current user coordinate system (UCS). That is the world coordinate system (WCS), which is the default system for all AutoCAD drawings. You'll change the orientation of the icon to the drawing and then change the orientation of the drawing to the screen.
The UCS defines the positive X and Y directions in your drawing. A drawing can have several UCSs, but can use only one at a time.
The WCS is the default UCS for all new drawings and remains available in all drawings.
This rotates the UCS icon 180° around the z-axis, to an upside-down position. The square box at the intersection of the x- and y-axes disappears, showing you that you're no longer using the default WCS (see Figure 10.38).
The entire drawing is rotated 180°, and the mirrored elevation is now right side up. Note that the UCS icon is now oriented the way it used to be, but the square in the icon is still missing. This signals that the current UCS is not the WCS.
NOTE You used the UCS command to reorient the UCS icon relative to the drawing. You then used the Current option of the PLAN command to reorient the drawing on the screen so that the positive X and Y directions of the current UCS are directed to the right and upward, respectively. This process is a little bit like turning your monitor upside down to get the correct orientation—but easier.
A brief inspection will tell you that the decks and stairs don't need any changes. The windows and roof need revisions, however, and the pop-out doesn't exist on this side of the cabin:
You can accomplish these tasks quickly by using commands with which you're now familiar:
After removing these lines, your elevation view should look like Figure 10.40.
The gap left after erasing the pop-out needs to be reconstructed.
Start the JOIN command by choosing the Home tab extended Modify panel Join tool.
After you've joined each of the rooflines into three individual segments, your view should look like Figure 10.41.
Once these are drawn, your elevation will look like Figure 10.42.
Your elevation should look like Figure 10.43.
You need to save the UCS you used to work on this elevation so that you can quickly return to it in the future, from the WCS or from any other UCS you might be in. The default AutoCAD workspace does not include access to UCS commands. To access these UCS commands, you'll load an additional Ribbon panel to the View Ribbon tab.
The Coordinates Ribbon panel is now included within the View Ribbon tab (see the bottom of Figure 10.44).
Click the UCS, Named UCS button on the Coordinates panel of the View tab to open the UCS dialog box. Alternatively, you can enter UCSMAN at the command line.
This will allow you to recall the UCS if you need to work on this elevation again.
TIP You can save any UCS in this way. The WCS is a permanent part of all drawings, so you never need to save it.
You can also save the view to be able to recall it quickly.
Back in the View Manager dialog box, North_Elev appears in the list of views.
TIP You can name and save any view of your drawing and then restore it later.
Now you can restore the drawing to its original orientation, with the side elevation below the floor plan and right side up. You do this by restoring the preset Top view.
Use the In-Canvas Viewport Control toolbar found in the upper-left corner of the drawing area to restore the preset Top view.
This zooms to Extents view and displays a plan view of the drawing with the X and Y positive directions in their default orientation.
You created a new UCS as a tool to flip the drawing upside down without changing its orientation with respect to the WCS. Now you'll use it again to create the front and back elevations.
You can generate the front and back elevations by using techniques similar to those you have been using for the two side elevations. You need to be able to transfer the heights of building components from one of the side elevations to either of the remaining elevations. To do this, you'll make a copy of the first elevation you drew, rotate it 90°, and then line it up so that you can transfer the heights to the front elevation. It's quite easy:
You need to transfer the height data from the side elevation to the front elevation. To ensure that the front elevation is the same distance from the floor plan as the side elevation, you'll use a 45° line that extends down and to the right from the rightmost and lowermost lines in the floor plan.
A cross appears at the intersection point. Don't click yet.
Vertical and horizontal tracking lines appear and intersect where the crosshair cursor is positioned, and a small X appears at the intersection. A tracking tooltip also appears.
This completes the diagonal reference line (see the bottom of Figure 10.48).
An X appears on the diagonal line where the ground line would intersect it if it were longer (see the top of Figure 10.50). This is called the implied intersection: a distinct object snap in itself, and also the osnap that is used when the Intersection osnap is specified but an intersection is not clicked. This is why the three dots appeared after the X symbols.
The rest of the process for creating the front elevation is straightforward and uses routines you have just learned. Here's a summary of the steps:
You won't be able to get the height line for the sliding glass door from the side elevation. It's 7′-3″ (2210 mm) from the top of the deck (see the middle of Figure 10.53).
The support post measures 1′-0″ (305 mm) across.
The railing posts have the same size and spacing on the front of the deck as they do on the sides.
This process can create a congested drawing, and you may want to draw the guidelines only as necessary to draw each component and then erase them. (See the bottom of Figure 10.53.)
TIP Although colors aren't visible in this book's grayscale print, it's good idea to “layer” your drawing when working with so many extension lines at once. Because each layer has a different color, assigning layers as you go will help you differentiate objects by color.
For instance, do not draw two lines on top of one another in areas where the foundation is behind the steps or support posts or where the vertical door lines are behind the railings. Only draw the features you would see if you were standing at the front of your cabin.
When you're finished, the east elevation should look like Figure 10.54.
You can create the rear elevation from a mirrored image of the front elevation. Here are the steps:
SELECTION CYCLING
When creating elevations, you might accidentally draw a line over an existing line. To catch this error, take the following steps:
If more than one object exists in a given area, two blue boxes will appear in the upper-right quadrant of the cursor, as shown here:
Now you'll revise the elevation to match the left side of the cabin.
When you're finished, the elevation should look like Figure 10.55.
When you have completed all the elevations, follow these steps to clean up and save the drawing:
The drawing looks like Figure 10.56.
This last view raises several questions: How will these drawings best fit on a page? How many pages will it take to illustrate these drawings? What size sheet should you use? At what scale will the drawing be printed? In traditional hand drafting, you wouldn't be able to draw the first line without answers to some of these questions. You have completed a great deal of the drawing on the computer without having to make decisions about scale and sheet size because, in AutoCAD, you draw in real-world scale, or full scale. This means that when you tell AutoCAD to draw a 10′ (3048 mm) line, it draws the line 10′ (3048 mm) long. If you inquire how long the line is, AutoCAD will tell you that it's 10′ (3048 mm) long. Your current view of the line might be to a certain scale, but that changes every time you zoom in or out. The line is stored in the computer as 10′ (3048 mm) long.
You need to make decisions about scale when you're choosing the sheet size, putting text and dimensions on the drawing, or using hatch patterns and non-continuous linetypes. (Chapter 11 covers hatch patterns, and Chapter 12 covers dimensioning.) You were able to avoid selecting a scale based on linetypes alone in Chapter 6, “Using Layers to Organize Your Drawing,” by setting all three LTSCALE variables to 1. Thanks to the flexibility this method provides, you were able to avoid committing to a scale so early in the project.
Instead you were largely able to postpone the scale decision until you began setting up your title block. At that point, you discovered that the largest scale that would allow you to keep the entire floor plan visible on a single sheet was about . That scale has a true ratio of 1:24, or a scale factor of 24. You'll get further into scale factors and true ratios of scales in the next chapter.
If you look at your I10A-FPLAYO.dwg (MI0A-FPLAYO.dwg) drawing with all elevations visible on the screen, the dashes in the dashed lines look like they might be too small, so you might need to increase the linetype scale factor. As you may recall, the easiest way to preview how the drawing scale affects linetypes is to change the annotation scale. This is possible because LTSCALE, PSLTSCALE, and MSLTSCALE are each set to 1.
Something else to consider is how the elevations you just drew will fit into your plotted plan set. If you were to thaw the title block's layer now, you would see that your elevations wouldn't all fit. Don't worry about that yet. Beginning with the next chapter, and right on through the end of this book, you'll need to make decisions about scale each step of the way.
Sometimes referred to as sections, interior elevations can be constructed using the same techniques you learned for constructing exterior elevations. You drop lines from a floor plan through offset height lines and then trim them away. Interior elevations usually include fixtures, built-in cabinets, and built-in shelves, and they show finishes. Each elevation consists of one wall and can include a side view of items on an adjacent wall if the item extends into the corner.
Not all walls appear in an elevation—usually only those that require special treatment or illustrate special building components. You might use one elevation to show a wall that has a window and to describe how the window is treated or finished, and then assume that all other windows in the building will be treated in the same way unless noted otherwise.
In the next chapter, you'll learn how to use hatch patterns and fills to enhance floor plans and elevations.
Here are three exercises for practicing the techniques you learned in this chapter. The last one will give you practice in basic orthogonal projection.
Exterior Elevations Open I10A-FPLAYO.dwg (M10A-FPLAYO.dwg), and revise each elevation by adding (38 mm) frames around the windows and doors. Add mullions, the dividers between windowpanes, to separate each window into four equal panes and add a rectangular window to the back door. Figure 10.57 shows the revised south elevation with the features added to the windows.
Interior Elevations For some practice with interior elevations, try drawing one or two elevations. You can measure the heights and sizes of various fixtures in your own home or office as a guide.
Orthogonal Projection Draw the three views of the block shown in Figure 10.58, following the procedures you used for the cabin elevations, except that, in this case, you'll use the procedure that mechanical drafters employ—that is, draw the front view first, and then develop the top and right side views from the front view. The completed drawing, named X10-00-OrthoProject.dwg, can be found on the book's website, www.sybex.com/go/autocad2013ner, or by visiting www.thecadgeek.com.
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