Thermal and Ignition Barriers: Where and When to Use with Spray Foam Insulation

Installing foam insulation is a technical process. That’s why it’s so important to work with an experienced contractor you trust to protect your investment. And having a bit of knowledge about the process can help you to ask good questions to ensure your spray insulation is done properly.

Thermal BarrierFor starters, all spray foam needs some kind of thermal barrier (most commonly ½-inch drywall/sheetrock) to separate the spray foam from occupied spaces. The thermal barrier is applied between with spray foam insulation and interior spaces to slow the temperature rise of the foam insulation during a fire and to delay the product’s involvement in a fire. TIP:  Ask your contractor for a copy of the ESR report for the product they intend to use. Spray foam products are tested independently and each has guidelines for barriers to qualify for codes.

Ignition BarrierFor attics and crawl spaces where access is only needed for utility service, an exception is made. These spaces must be protected by ignition barriers. This covering or coating is applied over the foam to slow the temperature increase of the foam in the event of a fire. Again, these are only to be used in non-inhabited locations. As with thermal barriers, ask your contractor for a copy of the ESR report – some spray foams are available with an ignition barrier built in, like Icynene LD-C-50 and Demilec APX.

None of this is to say that spray foam is a fire hazard. Most spray foams are a Class 1 Spray Foam, have fire retardants mixed in and in fact have better smoke development, flame spread numbers and auto ignition points than wood. The barriers required by codes are simply preventative measures to delay spread in the event of a fire. Spray foam is a very safe product when installed and used correctly.

Choosing the appropriate insulation products for your application will impact the function of your structure for years to come. If you have questions as you’re making this important decision, we would welcome the opportunity to review your plans to provide peace of mind that you select an insulation that will be safe and energy efficient.