In the early 1990s, it was announced that fiberglass had been classified as a “possible carcinogen,” and that products used in the HVAC industry (such as fiberglass ductboard) could be putting people in danger. This was due to the possibility of small fibers breaking free (from the body of the duct) and entering rooms that were being treated by the HVAC systems. In those rooms, this material could then be taken into the body through the respiratory process and lodge in the lungs. The concern was similar to problems relating to asbestos.

Because I take the well-being of people very seriously, it was immediately announced that unprotected fiberglass ductboard would no longer be allowed on any project—residential or otherwise—that I was involved with. However, the installation of polymer-lined ductboards would be acceptable. This was due to the polymer lining’s ability to hold glass fibers in place.

I followed the track of this investigation throughout the 1990s into the present and offer the following from the International Agency for Research on Cancer (IARC):

“Direct contact with fiberglass materials or exposure to airborne fiberglass dust may irritate the skin, eyes, nose, and throat. Fiberglass can cause itching due to mechanical irritation from the fibers. This is not an allergic reaction to the material. Breathing fibers may irritate the airways resulting in coughing and a scratchy throat. Some people are sensitive to the fibers, while others are not. Fiberglass insulation packages display cancer warning labels. These labels are required by the U.S. Occupational Safety and Health Administration (OSHA) based on determinations made by the International Agency for Research on Cancer (IARC) and the National Toxicology Program (NTP).

1994—NTP listed fiberglass as “reasonably anticipated to be a human carcinogen” based on animal data.

1998—The American Conference of Governmental Industrial Hygienists reviewed the available literature and concluded glass wool to be “carcinogenic in experimental animals at a relatively high dose, by route(s) of administration, at site(s), of histologic type(s) or by mechanism(s) that are not considered relevant to worker exposures.”

1999—OSHA and the manufacturers voluntarily agreed on ways to control workplace exposures to avoid irritation. As a result, OSHA has stated that it does not intend to regulate exposure to fiberglass insulation. The voluntary agreement, known as the Health & Safety Partnership Program, includes a recommended exposure level of 1.0 fiber per cubic centimeter (f/cc) based on an eight-hour workday and provides comprehensive work practices.

2000—The National Academy of Sciences (NAS) reported that epidemiological studies of glass fiber manufacturing workers indicate “glass fibers do not appear to increase the risk of respiratory system cancer.” The NAS supported the exposure limit of 1.0 f/cc that has been the industry recommendation since the early 1990s.

2001—The IARC working group revised their previous classification of glass wool being a possible carcinogen. It is currently considered not classifiable as a human carcinogen. Studies done in the past 15 years since the previous report was released do not provide enough evidence to link this material to any cancer risk.”^[1]

I also want to reference the following studies, which draw the same conclusions:

Agency for Toxic Substances and Disease Registry. Technical Briefing Paper: “Health Effects from Exposure to Fibrous Glass, Rock Wool or Slag Wool.” Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services, Atlanta, GA, 2002.

National Toxicology Program. Glasswool in Report on Carcinogens, 9th Edition. U.S. Department of Health and Human Services, National Toxicology Program, Research Triangle Park, NC, 2001.

“Man-Made Vitreous Fibres, Special-purpose glass fibres such as E-glass and ‘475’ glass fibres (Group 2B), Refractory ceramic fibres (Group 2B), Insulation glass wool (Group 3), Continuous glass filament (Group 3), Rock (stone) wool (Group 3), Slag wool (Group 3),” VOL.: 81 (2002), International Agency for Research on Cancer, World Health Organization, Lyon, France

The above information notwithstanding, there are still those out there, including Web sites, which would appear to be (otherwise) “legitimate” sources of information, that make serious claims to the contrary. Simply put—they are wrong.

So, for you, here is my advice when it comes to fiberglass.

When working with any glass fiber products, wear long-sleeved shirts with the collar and sleeves buttoned. Wear a dust mask and safety goggles.

Under normal conditions, once the glass panels are fabric wrapped, the fibers should be contained within.

When work is completed, use a vacuum cleaner to clean up any stray particles. Do not use a broom to clean up fiberglass dust, as this will raise and redistribute a large amount of particles. If available, a vacuum cleaner with a HEPA filter is the best way to go.

Common sense dictates that you wouldn’t want to dump this stuff in your body, but with a little bit of care, it’s perfectly safe to work with and have in a home environment.

Carpet, when placed on the walls of studios, can attenuate mid and some higher frequencies (the same as it will do on a floor), but is (again) not the answer for low frequencies.

This, too, is coupled with the fact that carpet is not made to be put on walls (with the exception of some Berber carpets that have test data certifying them for that purpose).

Figure 11.2 is from the Carpet and Rug Institute regarding the acoustic value of carpet:

Note that the NRC (noise reduction coefficient) for carpet is fairly low, especially when you consider that the only carpet you can put on walls is Berber carpet (or at least those Berber carpets that have been tested and approved). Berber carpet comes under the variable heading “increasing pile weight/height relationships in woven wool loop pile carpet.” Note that the NRC for this carpet is only 30 to 40 or roughly half that of the Auralex Sono-matt, and you still need to think about ease of installation.

Understanding NRC is easy—you take the average sound absorption coefficient measured at four frequencies: 250, 500, 1,000, and 2,000Hz expressed to the nearest integral multiple of 0.05. So it’s easy to see that you aren’t getting any great ratings at those frequencies if your NRC is only 30 to 40.

Next, you need to read this (also from the Carpet and Rug Institute), regarding the placement of carpet on walls:

“Carpet is manufactured for use as a floor covering, and installation on other surfaces, such as walls, is not recommended. Many carpet manufacturers will not assume any liability, real or implied, when carpet is applied on surfaces other than floors.”

Interestingly enough, most insurance companies won’t assume liability either. If you place carpet on walls, and it is determined that it contributed in any way to a fire, that is a perfect opening for your insurance company to walk away from you.

Once again—no low-frequency benefit—and little benefit for what it does provide, especially when you consider the risk at which you are placing yourself.

We’ve touched on this earlier in the book. These foams are only to be used for what they are made—shipping packaging. They do not attenuate sound the same way that products made specifically for that purpose do. I don’t care what your ears told you—your ears are wrong.

If, after all that’s happened with nightclubs and packing foams in recent years, anyone still wants to use these in their room(s), they must be crazy. Once again, your insurance company will drop you like a hot potato, and you can forget about collecting for a fire if that product is installed and contributed to a fire in any way.

Go back to Chapter 9 if you have any questions remaining and re-read the information there relating to foam products.

Yup, some people absolutely swear by these for use in studios as bass traps. They also make claims that they will help you big-time with sound isolation.

First, as you well know by now (having read the book to this point), isolation requires mass, which is sorely lacking from a mattress. Low-frequency attenuation requires mass and air, only one part (of which) is provided by a mattress. Mattresses will treat mid- and high-frequency transmissions (seem to be seeing a trend here with that), but, once again, the biggest problem in your rooms is going to be low-frequency modal and non-modal activities.

Second, safety is an issue again. Although these won’t take to flame quite the same way as packing foam, they will smolder for a long time before a fire actually takes off. You could well have a fire start in a mattress and not know it for hours after it began.

As always, because the acoustic benefits you might get from the material aren’t really helping you where you need it (as well as weighing in the safety factor), don’t even bother heading in this direction.

Human performance has certain capabilities and limitations that affect the outcome of work produced. When human beings make an error, they will assess the work and make a determination that the error is either acceptable or not acceptable. For example, a piece of drywall cut partly out of a square would be typically viewed as being acceptable, whereas a piece of wood trim (intended for a clear finish) not fitting properly would generally be viewed as being not acceptable. These decisions are easy to make, because in one case the drywall joint will be taped over and thus covered up, while the wood trim will be exposed for all to see.

Therein lies part of the problem.

People tend to view things that aren’t seen in the finished product as being not quite as important as the finished product itself. I’ve witnessed this time and time again during my many years in the construction industry. For example, there are framing carpenters who believe that framing doesn’t have to be cut perfectly square and tight-fitting because it gets covered up and you never see it. There are trim carpenters who don’t worry about painted trim fitting like it was cut with a razor blade, because the painters can just caulk the joint when they finish it. No one will know or see it in the finished product.

After all, close is good enough.

The fact is, especially in the case of sound-isolating construction, nothing could be further from the truth. It’s this mentality that is the cause for walls that were designed with a particular isolation in mind to actually have field ratings of 20dB less or worse. This happens in more cases than one might believe.

But what the heck, close is good enough.

How does one take the human equation out of the picture? Through the use of redundancy. You think “redundancy” because the odds of a person getting sloppy, making a mistake in exactly the same location, in the same exact manner, in an additional application, are pretty slim. They may very well get sloppy—they may very well make a mistake—but it will not be in the exact same location.

So, having workers stagger the joints in each and every layer of drywall protects you from bad seams. Making them caulk each and every edge of those layers moves any areas of imperfection around the perimeter, with good joint areas protecting weak ones. While we’re on the subject of good caulk joints versus weak caulk joints, let’s look at the issue of product deficiency. I wish I had a dime for every time I’ve seen a caulk joint fail. Sometimes, they failed based on sloppy workmanship, and sometimes they failed when the workmanship was perfect.

Every product manufactured goes through a QC (Quality Control) process, and all of those QC processes have tolerance ranges, which are the maximum/minimum size, amount of chemical additive, etc. that can be used in the process prior to the product developing a failure. For an engine, it might be the max/min piston diameter vs. the max/min cylinder diameter. So, if the cylinder diameter is below the minimum allowable, then the max diameter piston won’t fit within the chamber. By the same token, if the cylinder is over the maximum limit, then the smallest allowable piston might not create enough compression for the engine to operate properly.

The same goes with the chemical compounds that create the bonding capacities with caulk. There are very small variances allowed in the mixing process that will maintain the bonding and curing capacity of the products. But, if the ratios of the mixture are outside of these, the caulk will fail.

So what happens when we take the human factor into consideration with the QC process in these manufacturing plants? Someone in QC decides that an additional of an inch (beyond allowable tolerance) isn’t enough of a variance to throw out a run of 10,000 pistons, which end up being installed in some engines where the cylinders were at the maximum allowable tolerance—and you just bought yourself a lemon that never runs right.

In the case of caulk, someone in the QC process decides than an additional of an ounce of a particular chemical (beyond design tolerance) isn’t enough of a variance to justify throwing away 10,000 tubes of caulk—and you just bought some tubes that are going to fail.

But what can you expect, after all—close is good enough.

What makes this interesting is that it isn’t generally 100% of the run that’s out of tolerance. If the tolerance at the beginning of the run were right at the edge when that particular lot was being produced, then maybe only 5 to 8% are out of tolerance. If that were the case, would you throw away stock knowing that anywhere from 92 to 95% of the stock was good? Well, some people in QC would and some wouldn’t. (I know this for a fact because my father used to work in QC and forever had people angry with him because he would reject an entire lehr of glass bottles because they slipped over the allowable tolerances. People would say to him, “If ‘so and so’ had inspected this, he would have let it go out,” to which Dad would reply, “Then maybe you should have had him inspect it, but it isn’t going out with my stamp on it.”

So you pick up 100 tubes of caulk at your local lumberyard, 5 cases from that same lot, and anywhere from 5 to 8 tubes are going to have joint failures. Let me clarify this by saying that I am not telling you that for every case of caulk you buy you are going to have five to eight tubes of bad caulk. This is just an example of what could happen with a bad lot that slipped through the QC process.

How does one take product failure out of the equation? Once again (in the case of caulk)—redundancy. If you caulk only one layer of drywall, then any failure of the caulk joint affects you directly. But calking each and every edge of those layers moves any areas of imperfection around the perimeter, with good joint areas protecting weaker ones.

Trust me, invest the money and go the extra mile. It is that commitment to excellence that is going to guarantee success rather than failure.

I don’t know why, but I still find myself amazed every time I hear people spouting the same incorrect data, it seems like someone, somewhere, would finally get it right, but the misinformation on the Internet just seems to continue to make its rounds—almost as if it had a life all its own.

People claim that you can get great (cheap) isolation by putting carpet down, plywood over that, then a layer of gypsum drywall, another layer of plywood, and then finishing off with some pad and carpet (a great recipe for creating a feeding ground for mold, mites, and insect infestation). Others who say that loosely hanging a sheet of drywall at a slight angle in front of an existing wall will create an isolating panel that will increase the TL value of your wall. They tell you to make sure to put some fluffy insulation in between the existing drywall and the new floating sheet (no studs because it just rests against the base of the wall and a wood molding at the top) so that it not only acts as an isolator but also as a bass trap. Of course, they can’t tell you how it will perform, just that they did it and they “know it’s fantastic.”

And with the misinformation come the “acoustic experts” that start up companies. They are the people who sell isolation products that (when installed in accordance with their directions) take walls that were constructed in accordance with the building codes and turn them into walls that no longer conform to the code.

One company I found has products that require you to remove the drywall and then create their version of a staggered wall. (I will not mention a name here, just the concept, if you run across anyone selling products like this, run like the wind).You do this by building out every other stud so that your new drywall is bridging the studs in between without touching them.

Not a bad concept, but it does pose a problem. The Building Code (at least here in the States, you should verify the requirements in your own country if you don’t live here) has requirements for the fastening of drywall for both bearing and nonbearing walls. The Code reference is to a document entitled GA-216, which is a publication from the Gypsum Association that outlines the standards for the installation of drywall. It covers everything from one-layer walls to multilayered walls, from mechanically fastened to laminated panels.

One of the things it does is to specify the maximum stud spacing for walls receiving drywall panels. These requirements are dependent on the wall type (bearing/nonbearing), whether the wall is wood or metal studs, and what the thickness of the drywall is.

There are situations where the maximum stud spacing is 12”. Other times it is 16”, and almost as often (as 16”) it is 24”. But it is never more than 24”.

Because the vast majority of studs are spaced either 24” or 16” on center, that means that under the best of circumstances (with a wall framed 16” on center) your connections would be on 32” centers to use this product as designed by the manufacturer.

This is a code violation, but they never mention this on their Web site.

In addition to that, I spoke with a person who was almost a client of theirs (they claim almost magical improvements when their product is used), and they told him this would help him to stop the noise coming from his next-door neighbor’s apartment. Which means they were not only telling him to take a perfectly legal wall assembly apart to create the code violation I noted above, but also to create another code violation by modifying a rated, tested fire-separation assembly that is required under the code.

In some states doing this would actually be a criminal act. (Connecticut is one of those states.) And in most states doing this could lead to criminal charges if the act created a situation where a fire broke through the wall and someone was injured (or died) in part or whole due to the act of destroying the fire barrier.

Another problem that could arise due to this is the possibility that the wall in question may well be a shear wall required as a part of the engineering to help hold the building up when faced with strong winds or seismic events.

This may or may not be an issue in single family homes (depending on the size of the home and it’s location), but it is very commonplace for this technique to be used in apartment buildings, and quite often the walls in question are the party walls separating apartments from each other, or from hallways.

The company in question is obviously a start-up deal from a group of people who thought they had a good idea and figured it had to work. Heck, they might even have paid to have it tested acoustically. (The acoustical lab doing the testing doesn’t worry about code issues. You ask them to test something, they test it, you pay them, and you get the report, but none of that makes it code compliant, or safe.)

If it seems too good to be true, it probably is. Make it a point to check with a building official, an architect, or an engineer before you start tearing something apart because some company told you that their product would work.

These are just a couple of examples of things to walk away from. Just remember that for every real company out there, there are a dozen that do not have a clue.