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Spray Foam and Metal Buildings

Insulation Tips

To foam or not to foam. Why you might choose to use spray foam inside a metal building even though the interior is not heated or cooled.

One of our frequently asked questions is whether there is a benefit to spraying two or three inches of foam on the inside of a metal building, even though it is not going to be heated or cooled. The answer may surprise you.

Savings or Comfort?

Are you looking for savings or comfort? If a metal building is going to be air-conditioned (cooled) or heated, then we expect the building to be insulated. It is our job to help you save money by offering the best insulation possible. However, sometimes savings is not the key reason that you decide to buy spray foam insulation. Sometimes, it all comes down to comfort.

truck-in-front-of-building-green-cocoon-spray-foam-insulation

Baby It’s Hot in Here!

If the temperature outside is 100°F, then the outside skin of your metal building is going to be around 150°F. It won’t take long before the radiant heat from the metal skin radiates to the inside of the building.

Insulate with Spray Foam!

If you have high traffic in your building, or you plan to leave the doors open to allow large equipment to be moved, you may opt to not condition the structure. You may think it is a waste of time. But when you insulate the building on the inside, especially with spray foam, you create a radiant barrier— a barrier between the heat source and your living space.

In the south, for example, the inside temperature will remain around 100°F during the hottest part of the day, even after the sun goes down. The temperature will be pretty close to the outside roof deck. If you didn’t have that radiant break on the inside walls and underside of the roof deck, the radiant heat would come off of the metal and heat the space. Thus, you would get a hotter environment inside than the temperature outside because of the radiant load coming off of the roof deck.

You see this happen a lot inside attics, metal buildings, workshops, etc., where you don’t get consistent conditioning. If you have a radiant load that is building up and a surface that gets really hot, then it radiates some of that energy to the air inside the space.

If you have insulation questions, check out our Frequently Asked Questions page or contact us. We would be happy to help you!

Spray foam insulation being installed by The Green Cocoon of Salisbury, MA.

Do You Need a Thermal Barrier When Using Spray Foam?

Insulation Tips

There is a lot of confusion when it comes to thermal barriers regarding what they are and when they are needed with spray foam application. Luckily, we understand this subject and will explain the thermal barrier and the International Residential Code (IRC) in a way that you can understand.

What is a thermal barrier?

A thermal barrier is a material that is applied between spray foam insulation and the interior living space. Moreover, the IRC says that all foam plastic insulations have to be separated from the interior of the building by a 15-minute thermal barrier. One such barrier is half-inch gypsum board (drywall). Because any type of spray foam is combustible, along with most other building materials, we need to protect the wall from the foam. By installing gypsum board over the foam, we have protection on the inside of the building for a life-saving purpose.

The IRC is trying to provide enough time for occupants to get out of the house in case of fire. A thermal barrier will give an occupant about 15 minutes to escape.

Not every area of your home has to have a thermal barrier. So, what needs to be covered and what can be exposed?

Can spray foam be left exposed?

The quick answer is yes and no, because spray foam can be left exposed in some areas of the home with other areas requiring a thermal barrier, according to the code.

If the area of the home that has been sprayed with foam is directly connected to the living space or used for storage, then it has to be separated by a thermal barrier. This would be your exterior walls and ceilings.

spray foam insulation contractor spraying ceiling - green-cooon

There are exceptions to the rule, which are the crawl space, attic, and basement rim joists. Rim joists never require thermal barriers, and attics and crawl spaces that are not used for storage or living space do not need a thermal barrier. They’re already treated with an ignition barrier. The only time a crawl space or attic needs a thermal barrier is when the space is used as an auxiliary living space or storage.

There are a couple of ways to omit or provide an alternate to the thermal barrier. One of those is large scale test using something like a cementitious-based product. If it passes the test, it can be used as a stand-alone thermal barrier.

You could also use an intumescent coating (swells up when heated). It has been tested over a specific spray foam to provide an interior finish system that acts like a thermal barrier. For example, if you’re going to install spray foam on the underside of a roof deck in an open roof assembly like in a restaurant, you would put the spray foam on the underside. You can’t leave it exposed to the inside of the building, so you’ll need to use a thermal barrier to go over it, such as drywall or thermal barrier paint.  What do we do?

If you have an intumescent coating that has been approved, then you apply that over the spray foam. The coating is now an interior finish that we can leave exposed inside the restaurant, which meets interior standards.

Learn more about insulation code

In conclusion, you now have a grasp of thermal barriers, but you might have more questions about meeting insulation code in your area.

If you want to make sure your new home or remodeling project meets code, please contact us.

References

  1. Spray Foam Advisor, Thermal Barriers, Sep 29, 2017, sprayfoamadvisor.com
  2. Retrofoam of Michigan, What is a Thermal Barrier and When is it Needed with Spray Foam? December 26, 2018, retrofoamofmichigan.com
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