4 traps of spray foam insulation

Spray foam insulation is a great product. Homes insulated with it can be some of the most efficient and comfortable homes ever built. I have been to many of these homes and I can tell you that when spray foam is installed properly they outperform 99% of fiberglass batten and insulated homes. (I can also tell you that 73% of all statistics are compiled in the field, so please do not ask for documentation of that statistic.)

spray foam insulation near me is a great product. Homes insulated with it can be some of the most efficient and comfortable homes ever built. I have been to many of these homes and I can tell you that when spray foam is installed properly they outperform 99% of fiberglass batten and insulated homes. (I can also tell you that 73% of all statistics are compiled in the field, so please do not ask for documentation of that statistic.)

Aerosol foam comes in two flavors, open cell and closed cell, and provides both parts of the building envelope: the insulation and the air barrier. The building envelope must surround the conditioned space and the insulation must be in contact with the air barrier. Since spray foam is both an insulator and an air barrier, proper alignment of the insulation and the air barrier is ensured.

However, what is not guaranteed is that all spray foam houses are efficient and comfortable. I have seen several houses with problems even though they are insulated with spray foam. In order of prevalence, these are the problems I’ve seen, with explanations following the list:

• The spray foam is not thick enough.

• Aerosol foam installers overlooked some of the air leak sites.

• The spray foam installers did not understand the building envelope and sprayed too little or too much.

• The spray foam contracts and moves away from the frame.

• The spray foam is not thick enough.

This is more common with closed-cell foam, but it is also true with open-cell foam. Since closed-cell foam has a higher R-value per inch, installers generally spray 2 ″ on walls and 3 ″ on ceilings to meet the energy code requirements of R-13 and R-19, respectively. . (I’m not going to delve into the energy code here, but these numbers apply to many climate zones, the latter being allowed under UA’s offset rule. Check out the Energy Nerd blog on this topic if you want to discuss it.)

Open-cell foam generally fills the frame cavity, so it’s easy to tell if the installer has sprayed enough. Closed-cell foam does not fill the cavity, so you need to do a spot check in several places to make sure a short circuit does not occur.

Aerosol foam installers overlooked some of the air leak sites.

I once got a call to see a 10,000-square-foot house that had spray foam all over it, but the owners had a serious problem their first summer in the house. When I arrived I was taken to the master suite, where there were two towels on the floor, to catch the rain that fell from the supply registers on the ceiling!

The problem was that the installers overlooked some areas in the ceiling in the attic above the master bedroom, and the gaps around the ceiling of the tray allowed moist air to enter the room, where it naturally found the cool surface to condense.

As this example illustrates, it is important to seal the envelope completely. One of the biggest selling points of spray foam is its ability to seal the air, but it cannot seal places where it is not sprayed. One of the great things about using spray foam in new construction is that you can do a blower door test before the drywall goes in. Even better, you can test for leaks with a smoke machine.

The spray foam installers did not understand the building envelope and sprayed too little or too much.

In complex homes, seeing exactly where the building envelope is can be challenging. If the installer misses areas, it may or may not be an air leak, but it will be a thermal bypass due to the lack of insulation. Every part of the building envelope must be insulated, or the house will have excessive heat loss/gain.

Another problem I have seen is the installer spraying extra foam because he has not identified the location of the building envelope, the boundary between conditioned and unconditioned space. In the photo below, that wall with foam all over it has conditioned space on both sides. The owner paid more and got nothing for it.

The spray foam contracts and moves away from the frame.

I have seen this only once, and it was with closed-cell foam, but I have heard it happened with open-cell foam as well. I don’t know the details, but I have heard that it could be the result of a bad batch of chemicals, a wrong mix, or too high a temperature. Whatever the cause, it is not a good thing. The photo below shows how the spray foam came off the studs. A little bit of non-insulated area like that adds up to a lot of heat loss/gain when the whole house has that problem as it did here.