Does Your Spray Foam Insulation Need a Thermal or Ignition Barrier?

To say spray foam insulation has become popular in green building over the past decade is like saying Tom Brady is a good quarterback. It's an understatement in the truest sense of the word. Although it's unquestionably not used in every green building project, it's become one of the most popular ways to create an air-tight house. In the early days, building codes hadn't caught up with how properly to use this material, but that's changing. Change begets confusion, though, and the requirements for thermal and ignition barriers are one region where there's a quantity of that.

Do you need a thermal barrier?

Yes, unquestionably. If you put spray foam insulation in a building, it needs a thermal barrier. That's what separates it from the controlled spaces. If there's a fire in the building, a thermal barrier keeps the combustible spray foam from the actual flames to increase fire resistance. 

The standard customary material that can be used as a thermal barrier is 1/2" drywall or sheetrock. Anything else has to be approved as an 'equivalent thermal barrier' by undergoing tests for temperature syncromeshed and fire integrity. In some cases, however, you need only one test. 

This is where things get a little tricky. If a home has spray foam insulation in an attic or crawl space, the building code requires using materials or assemblies that offer some fire resistance but not as much as is required for a thermal barrier. If you've got spray foam insulation in an attic, for instance, it's probably already separated from the living space by a thermal barrier. Most ceilings are made of 1/2" drywall. But the spray foam is still susceptible to the attic in cases of fires and needs an ignition barrier.

When do you need an ignition barrier?

According to the IRC and IBC, an attic or crawl space needs an ignition barrier over the spray foam if space can be accessed but will not be used for storage or auxiliary living space. You don't need an ignition barrier if the area cannot be accessed without intersecting into it, if it is not connected to other spaces, and if it does not communicate with other cities.

One thing to be aware of is that not everything claiming to be a thermal or ignition barrier meets the requirements. If it's not on your building department's approved list, ask the company selling it for their test data and evidence of code approvals. You may need them to satisfy your building inspector.

What if your local inspector doesn't require anything? Well, it sure is tempting to keep your costs low and omit ignition barriers in attics and crawl spaces. But what if that house burns and the insurance company refuses to pay because there was no ignition barrier? It doesn't take a genius to know who the homeowners are going to come after.

The bottom line is that if you're using spray foam insulation, you need to know the code about thermal and ignition barriers and use them where essential. You need to know your materials, too, and what reduces in each case.

Want more info?

Call ArmorThane today!