When you’re planning to install new spray foam insulation or upgrade your existing one at home, it’s crucial to consider the spray foam’s fire resistance as it will help prevent putting your house and family at risk and give you the security you need.

Spray foam insulation is decently fire-resistant as it’s commonly treated with flame retardants to withstand heat and resist burning to a certain degree. However, it’s considered a combustible and flammable material and can catch fire when the temperature reaches 700°F.

If you wish to use spray foam insulation, it’s essential to know if it’s flammable or fire-resistant and consider the potential fire hazards and risks that come with it.

In this article, we’ll take a closer look at what makes spray foam insulation fire resistant, how effective it is in impeding a fire, and its potential hazards. 

Can Spray Foam Catch a Fire?

Spray foam insulation is made of two chemical materials, isocyanate and polyol resin, that are combined, which react and create an expanding foam. Its materials are usually treated with flame retardants to be decently fire-resistant. Unfortunately, spray foam is still flammable and can catch fire or burn when exposed to a heat source.

Spray foam insulation is considered a combustible material, igniting when the temperature from the extreme heat reaches 700°F. It’s also important to note that after applying, spray foam will emit gas or the propellant gas used to dispense of the foam as it expands and dries out. The propellant gas may catch fire and cause explosive force, especially when the ignition source is present. 

Is Spray Foam Fire Resistant?

Yes. Spray foam insulation is fire-resistant, as its materials are commonly treated with flame retardants to reduce the chances of it contributing to the spread of fire.

Unlike open-cell spray foam, Closed-cell spray foam is Class 1 fire-rated. This means the material is highly fire-resistant and does not spread flames quickly.

However, according to the International Residential Code (IRC) and most building codes, installed spray foam insulation installed on the basement walls’ interior needs to be covered with a 15-minute thermal barrier. If installed in an attic or crawl space, the code permits a less strict covering, which is an ignition barrier. 

When compared to other insulation types, spray foam insulation has less fire resistance properties.

Although fiberglass insulation can melt when exposed to a particular temperature, it’s highly heat-resistant and non-combustible because it’s made from glass fiber. In addition, fiberglass is non-combustible and doesn’t need to be treated with fire retardants. It can withstand until up to 1000°F, with an ignition temperature of around 1,112°F.

Contrary to popular belief, cellulose insulation is also fire-resistant and can be used for extreme temperatures. In addition, it’s typically treated with a fire retardant, making it highly heat-resistant. Cellulose can withstand temperatures of about 1,200°F and has a Class 1 fire rating. 

Another highly fire-resistant insulation type is Mineral wool or rock wool insulation. It’s a naturally non-combustible material, as it’s made of mineral rock. It can withstand extremely high temperatures above 1832°F and only starts to melt at 2,200°F.

What Are The Dangers Of Burning Spray Foam?

Spray foam insulation is commonly made of polyurethane and isocyanate, and when ignited, the materials will rapidly burn and produce dense smoke and toxic and irritating gases.

While applying, spray foam is also extremely dangerous as the propellent gas used to dispense spray foam can combust and explode or burst into flames, especially when in contact with an ignition force.

At the start of burning and decomposing materials, it can release toxic gases of carbon monoxide, isocyanates, hydrogen cyanide, benzene, nitrogen oxides, and acetaldehyde, among others.

Exposure to high concentrations of carbon monoxide can be dangerous to one’s health, as it can produce adverse health effects. It can also lead to Carbon monoxide poisoning, which occurs when oxygen in the red blood cells is replaced with carbon monoxide. 

The most common signs are dull headache, dizziness, blurred vision, nausea, vomiting, shortness of breath, confusion, and loss of consciousness. This is because there is inadequate oxygen delivery to the brain. Long periods of high carbon monoxide concentration can also lead to severe tissue damage or death. It can even kill in less than five minutes, especially in an enclosed space with improper ventilation.

Exposure to toxic chemicals in the air, such as isocyanates, can irritate the skin, eyes, and lungs. This is because isocyanates are highly reactive irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. Contact with the toxic fumes of burning spray foam insulation can also result in asphyxiation and severe respiratory issues, including asthma.

Another danger of burning spray foam insulation is that it produces heavy black smoke that can reduce the area’s visibility and impede the people inside from escaping. 

Can You Put Out A Burning Spray Foam Insulation Yourself?

Since burning or melting spray foam insulation can be highly dangerous to one’s health, especially when exposed for long periods, it’s best to call firefighters and let the professionals handle the burning spray foam instead. 

The fumes and smoke can also reduce visibility, which could hinder the process and be difficult, especially if inexperienced. In addition, the fumes produced when spray foam is ignited can make the house occupants unconscious and even lead to temporary blindness.

In addition, immediately evacuating when the spray foam insulation is burning is preferred to prevent any fatal circumstances.

How to Prevent Spray Foam From Burning? 

It’s important to use recognized, high-quality fire-rated spray foam insulation products to ensure that they wouldn’t burn easily and contribute to the spread of fire. It’s also crucial that these products meet all safety regulations to reduce the risk of spray foam insulation burning. 

Following local building codes is also essential to ensure fire safety. It’s best to contact and let licensed professional contractors apply to spray foam insulation as improperly installed spray foam can be a hazardous fire hazard. Doing so will minimize fire risk and give you security and peace of mind.

In addition to using fire-rated spray foam insulation, it’s good to use a thermal barrier between the spray foam and the house’s interior living space. This can help separate the combustible spray foam from the interior space to prevent the spread of fire. 

Most building codes, including International Residential Code (IRC), require covering the spray foam insulation with a 15-minute thermal barrier when it’s installed on the basement walls’ interior. However, the code permits using an ignition barrier if the spray foam is installed in an attic or crawl space. This helps decrease the cases of fire by 50%.

Another precaution is to check the electrical wiring before and after the spray foam insulation installation, as faulty or damaged wiring can result in sparking and create fire when in contact with an ignition source. Regular maintenance check is also recommended, as doing so will help prevent spray foam from burning.

It’s also best to keep the spray foam insulation away from any heat or ignition sources that can spark flames, such as light bulbs, furniture, wood, appliances, and open flames since it’s highly combustible. 


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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