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Does My Roof Need to Breathe?

attic insulation | FAQ

Blog Feature
Amanda Ringler

By: Amanda Ringler on March 23rd, 2022

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While researching insulating an attic with spray foam insulation, you may have seen that it is essential for the roof of your home to breathe.

Well, that’s not necessarily correct.

RetroFoam of Michigan has more than 20 years of experience insulating thousands of attics across the Lower Peninsula. With that experience comes the knowledge of how to insulate an attic in a way that keeps your home comfortable and running more energy efficient while saving you money.

Here's everything you need to know about spray foam attic insulation and how it affects your roof. 

Insulating an Attic Roof or Floor with Spray Foam

There are two installation options for adding spray foam insulation in attics -- either the roof deck or the attic flat can be sprayed.

Insulating the attic roof with spray foam makes it part of the conditioned space in your home. Air will circulate from the living space up to the attic, hit the spray foam barrier, and then move back down.

Adding spray foam to the attic flat will seal it off from the rest of your house. The air barrier created with spray foam insulation blocks the air you pay to heat and cool from moving up into the attic.

These installation methods will determine whether the attic venting systems will work best for you.

Unvented Attic System

When creating an unvented attic system, the insulation contractor is installing spray foam right onto the roof deck of the house.

The concern is that this will cause a hot roof scenario or that the roof can't breathe. The adage that the roof needs to breathe isn’t necessarily correct.

If there is ventilation in the attic, that ventilation is in place for the main purpose of getting moisture out. That’s because moisture gets in through cracks and crevices in the roof deck.

When the entire roof deck is sprayed with foam insulation, everything is sealed off, so moisture can’t get in. This also means that you don’t need any ventilation in the attic to get the moisture out because the spray foam insulation keeps it out.

You also don't have to worry about having a hot roof because that is really a misnomer coming from the earliest days of insulating an attic when people believed the insulation served as a heat source.

Let's take a look now at what a vented attic looks like.

Vented Attic System

In some rare cases, it makes more sense and is more beneficial to insulate the floor of the attic instead of the roof deck.

This is considered a vented system.

The first thing a good contractor must keep in mind is circulation. When you insulate the floor of the attic with spray foam, you are cutting that space off from the rest of the house creating an air seal. When this is done the attic must be vented.

The purpose of the vents is to bring cool air from outside into the attic to help it maintain a constant temperature, according to Energy Star.

The problem with this system is the temperature difference between the attic and the rest of the home will cause condensation, which promotes mold and mildew growth.

Learning More About the Benefits of Spray Foam Insulation

Now that we've cleared up that your roof doesn't actually need to breathe, you might be yearning to learn more about spray foam insulation for other areas of your home.

If that's the case, check out our foam insulation Learning Center. You'll find a ton of great resources there, as well as answers to the most frequently asked questions.

Related Articles

Clearing Up Misconceptions About Spray Foam Insulation

Does Spray Foam Damage Roof Shingles?

Vented vs. Unvented Attic: Which is Better?

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About Amanda Ringler

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.