Is Spray Foam Insulation Flammable?

Some friends of mine bought their first house recently. Within a day, they had already dealt with a water leak and all the damage it caused.

Homeownership comes with worries and responsibilities. Whether you are building a new home or making your existing home more comfortable, there is a burden to make the best decisions you can with the knowledge you have.

As you consider insulation options, you must consider fire risk. Is spray foam insulation more likely to cause or contribute to a house fire?

Our team at South Central Services has worked with hundreds of clients as their insulation contractor. We could give the short answer to that question: no, spray foam insulation does not hold or promote a flame. But we want to share the details about construction science with you so you can be confident in your insulation choice.

By the time you finish this article, you'll know:

• What fire rating classifications are
• What it means for something to be combustible
• The difference between ignition barriers and thermal barriers
• Whether or not spray foam poses fire risks

Don't have time to read right now? Check out everything you need to know at a glance.

How Construction Science Helps Prevent Fire

In construction, we need scientific ways to measure the materials that we build with. We have to classify which materials have what properties. This way, when creating a new structure, we know how the materials can work together to make a safe building.

Fire rating classifications measure building materials for the fire risks they pose. These classifications range from Class 1 to Class 5. Only Class 1, 2, and 3 materials can help prevent fires. In almost every case, building materials must be Class 1 to be up-to-code.

Many organizations evaluate materials for fire rating classifications. An example is the American Society for Testing and Materials tunnel test (ASTM E84). This test exposes materials to fire over a period of time, and the smoke development and flame spread are measured.

Can Combustible Materials Have A Class 1 Rating?

Combustible materials are organic materials that could eventually catch fire if exposed to flame. Plastic foam, cellulose, and wood are all examples of flammable materials. They are also all common building materials.

Incombustible materials do not burn if exposed to fire. An example would be fiberglass. Generally, incombustible materials do not need to be tested for flame spread or smoke development. However, fiberglass batt insulation does have paper backings that are combustible, so fiberglass is still tested for fire rating.

Combustible materials can have a Class 1 rating if their smoke development is below 450 and their flame spread is 25 or less. These are numbers used to index or score tested materials. They do not translate to some other measure, such as time.

For combustible materials to have properties to pass these tests, they require ignition barriers. To meet building code, Class 1 materials may also require thermal barriers.

What Are Ignition Barriers?

An ignition barrier is something that helps to prevent the insulation from igniting.

Closed cell spray foam has the most expansive applications and has a built-in ignition barrier.

Open cell spray foam does not have this built-in ignition barrier, but ignition barrier coatings can be added. These coatings can be added to open cell foam applications because of building code specifications.

What Are Thermal Barriers?

A thermal barrier is a physical barrier that has to be burned through for flame to reach the insulation. An example of a thermal barrier is the drywall on the walls of your home.

Thermal barriers are often measured in time. Drywall is a half-inch thick, but in terms of the barrier it provides, it is a fifteen-minute thermal barrier. It would take fifteen minutes for the drywall to be burned through and expose the insulation to flame.

Specific thermal barriers can also be spray applied directly to the foam. These liquid thermal barriers carry robust certifications.

Codes can also require walls to have thermal barriers coded for a certain amount of time.

Can Spray Foam Increase The Risk Of Fire?

Spray foam does not increase the risk of fire. While it is a combustible material, spray foam insulation is a tested building material. During construction, there are codes and regulations that contractors must follow. Manufacturers produce spray foams that meet these standards.

What Happens To Spray Foam Insulation During A Fire?

For spray foam encased in the walls of a home, a fire would need to burn through the drywall thermal barrier before reaching the foam. Since the foam is combustible, it would eventually burn. Depending on the foam application, an ignition barrier may extend the time it takes for the foam to catch fire.

Once the source of the fire is put out, the flames on the insulation should extinguish on their own.

Spray Foam Is Not More Likely To Cause Or Contribute To Fire Than Other Insulations.

House fires are a tragedy that no one wants to face. Wondering about the materials in your home and educating yourself on the potential risks is normal.

Our homes are decorated and filled with combustible materials. However, the materials creating the structures of our homes can be engineered to help prevent the tragedy of house fires. Building codes require these quality materials to be assembled in a way that minimizes fire risk. Knowing that can give peace of mind.

If you are building a new home, discuss these topics with your contractors. As professionals, they can share specific details about your space, the building codes of your area, and the specifications helping to keep your home safe.

Now that you understand how spray foam responds to fire, these are your next steps.

• Learn whether spray foam is a safe insulation product for your home
• Discover how spray foam insulation would respond to flooding
• Understand how spray foam can help prevent pest infestations