Asked & Answered: EPS Foam and Fire Retardants

There are some misconceptions about EPS foam in the building industry.

In this Asked & Answered we discuss how fire retardants used in EPS foam as used in building products. 

EPS Foam and Fire Retardants

EPS foam, when used in building products, contains a fire retardant added to the bead before it is expanded and molded. Additionally EPS foam with this fire retardant is not a fuel source. When exposed to high heat, EPS foam doesn’t burn, it melts. This is due to the fact that the EPS is expanded with steam and only contains air. The EPS foam used in packaging and shipping is not the same as the EPS foam used in construction products.

EPS foam as a building product is superior to many other materials used for construction. It is superior to standard poured wall construction because of the insulation value of the EPS foam. It is both the fire retardant and the insulation value of the foam that makes it perfectly suited to help protect structures during a wildfire. The ICF walls prevent the heat of the fire from transferring to the interior of the structure for several hours. In a wildfire situation, this is generally longer than the fire burns in a given area.

For a fire to transfer to the inside of an ICF structure it must heat the outside finish (brick, siding, stucco, etc.) to a temperature that will cause ignition of the next layer beneath (EPS Foam). That layer must be consumed and burn at a hot enough temperature to transfer enough heat to the next layer, (a reinforced concrete wall). The fire must still be hot enough to then transfers enough heat to the inside layer (another EPS foam layer) which also must be consumed before transferring enough heat to ignite the drywall or interior finish.

BuildBlock ICFs are tested by Intertek and the wall will last 4+ hours. Untreated EPS foam burns at 650° to 700°F with a flame source. It won’t continue burning on its own until 840° to 930°F is reached. Wood burns at  480° to 660°F. Most fires are relatively fast moving and don’t have the fuel source or longevity to provide enough heat to move to the inside of the structure through the wall. 

Designing your home with this in mind and incorporating other fire-retardant materials in roofing and exterior finishes will give you and your family safety and peace of mind in the face of disaster.

See our Intertek test results here: https://buildblock.com/technical-support/product-testing/ 

Downloads

EPS_Compliance_Document.pdf EPSIA-Polystyrene-Industry-Flame-Retardants-Bulletin.pdf