Why Does Spray Foam Insulation Off-Gas?

You were excited about spray foam as an insulation option. Then, you heard something about toxic fumes. You haven’t written off spray foam yet, but you have questions that must be answered. Does spray foam really off-gas toxic fumes? How long will it off-gas? Can I prevent it from off-gassing? Could off-gassing fumes harm my family?

South Central Services has installed spray foam insulation in hundreds of homes in and around Chambersburg, PA. As the contractors applying the foam, we take the necessary precautions to protect ourselves from off-gassing fumes. We know the science behind off-gassing and would like to share that information with you.

By the end of this article, you will understand:

• What off-gassing is
• Why off-gassing happens
• How long off-gassing can occur

What Is Off-Gassing?

Off-gassing is the release of volatile organic compounds (VOCs) and other chemicals into the air. Off-gassing is a byproduct of a chemical reaction. When a chemical reaction occurs to form polyurethane plastic products, off-gassing naturally occurs.

Off-gassing is more common than you might think. Polyurethane can be found in the soles of your shoes, in your car seats, and in your memory foam mattress.

New car smell and new shoe smell are technically off-gassing fumes. When purchasing a new memory foam mattress, manufacturers recommend letting the mattress air out for a day before anyone sleeps on it. Right after being manufactured, products created from chemical reactions will off-gas.

Does the common occurrence of off-gassing mean it is okay to inhale? No. Off-gassing fumes are toxic. In significant quantities, that toxicity can cause respiratory problems.

Why Does Spray Foam Off-Gas?

Since spray polyurethane foam is created from a chemical reaction, off-gassing will occur. The finished spray foam product cannot be made without the byproducts of heat and off-gassing fumes.

Chemical reactions are science experiments. You cannot change variables in the experiment and expect the same result. Chemical reactions create byproducts in addition to the end goal products. You cannot change how a product is made to avoid certain byproducts, at least in the case of spray foam. For polyurethane manufacturing, off-gassing is a byproduct.

Below is a diagram of the chemical reaction that creates spray foam.

Off-gassing during manufacturing cannot be avoided. To protect themselves while installing spray foam, contractors wear respirators and other personal protective equipment (PPE). Residents and pets are asked to vacate while buildings are sprayed for their health and safety.

How Long Can Off-Gassing Occur?

For spray foam installed on-ratio within manufacturer guidelines, off-gassing will stop after 24 hours. Off-gassing does not stop at 24 hours because 24 is a magical number, but because there’s only a byproduct due to the chemical reaction. When the reaction stops, the product and byproducts cannot be created anymore. A day after the reaction has stopped, the product is cured and the byproducts have dissipated.

For spray foam that is installed off-ratio, off-gassing could continue indefinitely if some amount of one chemical is left over without anything to react with.

The Bottom Line About Off-Gassing and Spray Foam Insulation

Spray polyurethane foam will off-gas as a byproduct of manufacturing. As long as the foam was installed on-ratio and within manufacturer guidelines, all of the chemicals in the reaction are gone. Off-gassing will stop after 24 hours. The spray foam product is stable and poses no health risks at this point.

Want more information on foam installed off-ratio or outside of manufacturer guidelines? Learn more about spray foam failure and how to avoid it.

Curious about the chemical reaction that creates spray foam? Check out our article about how spray foam insulation is made.

Ready to find your spray foam insulation contractor? Choosing a contractor you trust is one of the most important steps. Read about all the signs of a reliable spray foam contractor in our article.