Common pitfalls in the installation of fiberglass batt insulation
In the last three months my company has been extremely busy with insulation inspections for multi-family and single-family projects as they go through a green certification process for EarthCraft House or EarthCraft Multifamily. What I have seen out in the field varies greatly.
Fiberglass batt insulation is a good product when install properly. Properly installed insulation is so important, and it has such a huge impact on the energy performance of a building that RESNET and Energy Star developed standards in order to grade the quality of the installation. One key variable in Energy Models is to select the quality of the installation, and if you where to change the grade from "Grade I" to "Grade III" you would see the home's HERS Index increase. In other words you get penalized for poor installation techniques.
So batts, although they are a great product, are at the mercy of skills of the crew doing the installation. This fact is what is making spray foam insulation or blown in cellulose so popular because of its ease of installation, and low margin of error by the installer.
The following are examples of what not to do when using batt insulation:
On the picture to the left you can see how the batt was compressed behind the electrical outlet. Also note that it was side stapled too far into the wall cavity. To properly install this insulation, the crew should have cut around the electrical outlet, put insulation behind the box, and if side staples were still required, to do it at the very edge of front of the stub. These criteria should be applied to any obstruction that is inside the wall cavity. You want to reduce compression on the batt as much as possible.
On this one you can see again the problem with the outlet, but can also note how they did not put any insulation behind the plumbing pipe. In this case the batt insulation should had been split in the center, and completely wrapped around the plumbing pipe to reduce compression on the wall cavity.
This picture shows how the batt was a bit longer than the heights of the cavity and it was compressed at the bottom plate of the wall. You can also note how it was side stapled, exposing about 1/3 of the stub. This will leave an air pocket once the drywall is installed.
Now, how should fiberglass batt insulation look like if it was properly installed? It should look like this:
Note how the insulation was cut around the electrical outlets, and compression has been greatly minimized. This will most likely qualify as a Grade I installation.
In summary, just look for nicely installed insulation. In this case, looks do matter.
Luis Imery Luis Imery, through his business the Imery Group, is a full service construction, home energy performance, green certification and real estate group specializing in infusing sustainability in every facet of the real estate cycle. Its construction division has become pioneers in the Athens, GA area in green building of speculative, custom and design-built construction. Just in 2011 they have over 110 units slated for green certification under the EarthCraft program. www