Fact or fiction – spray foam will damage your roof shingles and void your warranty.
This is fiction and comes from the early days of insulating attics. People used to believe insulation was a heat source, which is where this myth comes from.
Unfortunately, there are still contractors who believe this is the gospel and say that spraying the roof deck could void any warranty on the shingles.
RetroFoam of Michigan has more than 20 years of experience insulating attics, so we've heard from homeowners their concerns about their shingles. We've also helped to alleviate those fears once those homeowners start feeling and seeing the benefits of creating an air seal in the attic.
I have more than 37 years of experience in the construction industry, so I can tell you from my experience that spray foam insulation isn't going to hurt your shingles. You don't have to take my word for it, but I have found research to back this up to put your mind at ease.
Is Spray Foam Bad for Shingles?
I first encountered this when I talked to a homeowner who had done a ton of research before requesting an estimate.
Unfortunately, during her research process, her roofer told her the spray foam would make her shingles curl because they would overheat. I explained to her where this misconception came from when people believed insulation was a heat source and were concerned about having a hot roof.
The hot roof is a term that comes from the earliest days of insulating attics.
Spray foam insulation is a barrier between two areas of different temperatures, so your attic would be the same temperature as the rest of your house, even though it is cold outside.
If you've never heard the phrase hot roof, I'm sure you've heard of an unvented attic. If your roof deck has been insulated, that means your attic space is now part of your home's conditioned space. This method of insulating the attic is good for your roof because it helps prevent ice dams.
The unvented system could make the temperature of your roof go up a little, but I found research that states that a slight temperature change won't hurt your shingles.
The Florida Solar Energy Center did a study a few years ago during the peak summer months in Florida – a state that gets much hotter than Michigan – measuring the temperatures of roof shingles above an attic with a radiant barrier.
Depending on the color of the shingles, the study found the shingles' peak temperatures were between 2- and 5 degrees Fahrenheit higher than the temperature of shingles in the same conditions without a radiant barrier.
This study means you can insulate your home's roof deck foam insulation without adversely affecting your shingles.
Foam insulation creates an air seal, keeping that hot air out during the summer and your cool air inside.
Insulating Your Attic with Spray Foam
Now that we've shown you the research and you see for yourself that your shingles won't curl or get ruined, I recommend looking at your paperwork for your shingles.
While spray foam won't cause any damage to the roof shingles, some contractors will still void the warranty because they are stuck in that old way of thinking. If this is the case, it doesn't hurt to have a conversation with them to get on the same page.
Now, you might be curious about the benefits of foam insulation in your attic. You can find all of the answers to your questions, as well as some you might still need to think of, at the Learning Center on our website.
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