Wednesday, March 3, 2021
Preventing Spray Foam Insulation Fails
Spray foam insulation is terrific for the building envelope. Spray foam insulation is a great product. Residences insulated with it can be a few of the most efficient and comfortable homes developed. I've been in lots of these homes and can inform you that when spray foam is set up appropriately, they surpass 99% of fiberglass batt-insulated, stick-built houses. I can likewise tell you that 73% of all stats are made up on the spot, so please do not ask for paperwork of that figure.
Spray foam insulation is a terrific product. Homes insulated with it can be some of the most effective and comfortable houses developed. I've remained in lots of these houses and can inform you that when spray foam is set up properly, they outshine 99% of fiberglass batt-insulated, stick-built homes. (I can likewise tell you that 73% of all statistics are made up on the spot, so please do not request for documents of that statistic.
Spray foam is available in two tastes, open cell and closed cell, and offers both parts of the building envelope-- the insulation and the air barrier. The structured envelope needs to entirely surround the conditioned space, and the insulation needs to be in contact with the air barrier. Since spray foam is both insulation and air barrier, proper positioning of insulation and air barrier is guaranteed.
What's not ensured, nevertheless, is that all spray foam homes will be efficient and comfy. I've seen a number of homes with issues even though they're insulated with spray foam. In order of occurrence, here are the potential fails I've seen, with explanations following the list:
Spray foam isn't thick enough.
Spray foam installers missed out on some of the air leakage websites.
Spray foam installers didn't understand the structure envelope and sprayed either too little or excessive.
Spray foam agreements and pulls away from framing.
Spray foam isn't thick enough.
This is more typical with closed-cell foam, but it happens with open-cell foam, too. Since closed-cell foam has a higher R-value per inch, installers generally spray 2 ″ in walls and 3 ″ in rooflines to satisfy the energy code requirements of R-13 and R-19, respectively. (I'm not going to dive into the energy code here, however, these numbers apply to lots of climate zones, the latter being enabled under the UA tradeoffs rule. See the Energy Nerd's blog on this topic if you want to argue.).
Open-cell foam generally fills the framing cavity completely, so it's easy to tell if the installer has actually sprayed enough. Closed-cell foam doesn't fill the cavity, so you've got to spot check in a bunch of locations to make certain you do not get shorted.
The video below is from a house near Charleston, South Carolina that I checked out just recently, and you'll see that the house owner in this case didn't get his cash's worth. I understood immediately when I strolled into the attic that something was wrong due to the fact that it was hot up there. In a properly insulated spray foam attic, the temperature level will not be much higher than your house temperature level.
The issue was that the installer was doing his first spray foam job ever, and the density of the insulation differed from absolutely no (noticeable roof deck) to about 9 ″. Unfortunately, excellent average density doesn't cut it. The coverage requires to be uniform since a lot of heat will go through the under-insulated locations. (See my short article on flat or bumpy insulation efficiency.).
Spray foam installers missed out on a few of the air leak sites.
Once I got a call to take a look at a 10,000 square foot home that had spray foam throughout, however, the owners had a serious issue in their first summer in the house. When I got here, they took me to the master suite, where two towels were on the floor-- to capture the rain falling off of the supply signs up in the ceiling!
The issue was that the installers missed out on some locations at the soffit in the attic above the master bedroom, and spaces around the tray ceiling allowed the humid air into the room, where it naturally discovered the cold surface to condense on.
As this example illustrates, it's crucial to seal the envelope totally. One of spray foam's most significant selling points is its air-sealing capability, but it can't seal locations where it's not sprayed. Among the good things about using spray foam in brand-new building and construction is that you can do a Blower Door test prior to the drywall goes in. Even much better, you can check for leakages with a fog maker.
Spray foam installers didn't understand the structure envelope and sprayed either too little or excessive.
In intricate houses, seeing precisely where the building envelope is can be an obstacle. If the installer misses locations, it may or may not be an air leakage, but it will absolutely be a thermal bypass because of the lack of insulation. Every part of the building envelope must be insulated, or the home will have excess heat loss/gain.
Another issue I've seen is that the installer sprays additional foam due to the fact that they haven't determined the place of the structure envelope, the border between conditioned and unconditioned area. In the photo listed below, that wall with foam all over it has conditioned space on both sides. The homeowner paid additional and got nothing for it.
Spray foam is squandered on partition walls.
Spray foam contracts and pulls away from framing.
I've seen this just as soon as, and it was with closed-cell foam, however, I've heard of it occurring with open-cell foam, too. I do not know the information, but I've heard it could arise from a bad batch of chemicals, incorrect mixing, or too expensive a temperature. Whatever the cause, it's not a good idea. The picture listed below demonstrates how the spray foam pulled away from the studs. A little bit of uninsulated area like that adds up to a great deal of heat loss/gain when the whole house has that problem, as it did here.
Conclusion.
Do not presume that just because a house is insulated with spray foam that it's immediately a winner. Every item has its risks, and spray foam is no exception. The bright side, though, is that spray foam's problems are normally less regular and easier to conquer with correct preparation and follow-through.
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