Spray foam insulation is safe.
Spray foam insulation is absolutely safe once the installation process is complete. There is no evidence that spray foam insulation is harmful to building occupants. Spray foam insulation has been used in buildings occupied by human beings for over 40 years without any noticeable health effects.
Installed and cured (hardened) polyurethane foam is chemically inert and poses no environmental or health risk. Research studies show that the raw ingredient chemicals used to spray the foam quickly break down to harmless organic molecules when dispersed in the air or inhaled. No reproductive or carcinogenic effects have been observed.
However, during the installation process, dust residues from the hardened foam can irritate the skin and soft tissues in the nose, throat and lungs. Consequently, workers should wear protective clothing and equipment and the work area should be well ventilated after the installation work is complete.
We live and work in spray foam-insulated homes and buildings. We would never knowingly expose our employees or our families to harmful building materials. However, we understand that it is necessary to provide specific answers to some of the more hysterical information and concerns that have found their way into a small number of Internet blogs. This goal of this page is to provide you with useful facts, so you can make an informed decision about the safety of spray foam insulation.
The chemicals used during the spray polyurethane foam installation process have been well studied.
The toxicology of MDI and TDI has been well investigated in experimental animals and biological systems. Researchers found that the diisocyanates are relatively non-toxic even when ingested orally. When inhaled, MDI and TDI irritate the respiratory tract. MDI and TDI also irritate the skin and eyes. However, airborne and inhaled diisocyanates react very rapidly and break down to generally harmless precursor molecules. Studies of repeated inhalation exposure have assessed effects on reproduction and carcinogenic potential. No significant reproductive or carcinogenic effects have been found. No carcinogenic effect was found in a study of lifetime inhalation of TDI vapor.3
Environmental Protection Agency (EPA) concerns about spray foam insulation are concerned with workplace safety.
The process of spraying the ingredients that combine to form polyurethane foam insulation produces vapors that can irritate the skin and soft membranes in the nose, throat and lungs. However, these vapors disperse and are ventilated to the outside air within less than 24 hours. Once the finished polyurethane foam hardens—a process called curing that is completed within a matter of minutes to a couple of hours—the finished insulation is chemically inert. This means that the hardened foam will not react with chemicals or substances in the surrounding environment, including air and moisture. It is highly unusual for any residues of the original ingredients to remain after the curing process is complete.
Still, how can you be sure that polyurethane foam is safe for your home? Well, consider that the EPA has no plans to study the safety of cured polyurethane foam. EPA’s efforts are directed toward studying the effects of the chemicals that exist during the installation process, before they combine to form the finished polyurethane or dissipate into the air. Diisocyanate vapors from uncured foam can irritate the skin, nasal passages and lungs if inhaled and can aggravate asthma. Here is a direct quote from the EPA’s action plan summary for Methylene Diphenyl Diisocyanate (MDI) and Related Compounds:
“EPA is concerned about potential health effects that may result from exposures to the consumer or self-employed worker while using products containing uncured (unreacted) MDI and its related polyisocyanates (e.g., spray-applied foam sealants, adhesives, and coatings) or incidental exposures to the general population while such products are used in or around buildings including homes or schools.” (Empasis added.)
In other words, workplace safety. Safety concerns involving spray foam insulation and related products have to do with individuals installing the material, not the home or building occupants. The VOCs in spray foam insulation dissipate within a few hours of installation. Spray foam insulation becomes chemically inert once it has cured. The curing process takes minutes or, at most, a few hours.
How can you tell when spray foam insulation has finished curing?
Generally, people can reenter the area when the insulating foam sealant has hardened to the point where it is considered “tack free” (no longer wet or sticky on the surface). The amount of time it takes for the foam to cure or harden varies depending on the product-specific formulation, temperature, humidity, the amount of foam being sprayed, and other variables. Typically, insulating foams cure quickly at moderate temperatures and humidity. The foam surface cures first, and then gradually cures inside of the foam body. The thicker the foam is applied, the longer it takes to cure throughout. Spraying a mist of water on the substrate and/or between layers of foam can speed up the curing process. It can take from five minutes to an hour for the foam to become tack-free. Full cure is usually reached from eight to 24 hours, depending upon the product and site conditions. Your installation technician should be able to provide you with a good estimate of the cure time.
A few words about volatile organic compounds
You can find a lot of information on the Internet about the evils of “volatile organic compounds,” or VOCs. VOCs are substances that have boiling points at or near normal air temperatures. This means they can produce vapors—by a vaporization process called outgassing—at ordinary room temperatures. VOCs are everywhere in our environment. The aroma of flower blossoms is due to the vaporization of plant VOCs. And the practice of aromatherapy, which has been around for thousands of years, involves inhaling the VOCs present in plant, fruit and tree oils such as citrus, coconut, peppermint, frankincense and lavendar.
VOCs can also be manmade and some are toxic. The following products and materials typically contain potentially harmful VOCs:
- glues and adhesives
- wall-to-wall carpet
- composite (pressboard) furniture
- furniture upholstery
New product odors (including that “new car smell”) are caused by VOCs. And as you probably know from your own experience, these “new” smells quickly dissipate and are ventilated to the outside air within a few hours or days.
But here is the really important thing to remember: The fact that toxic VOCs are present in an indoor environment does not necessarily mean that the VOCs are present in a concentration strong enough or sufficiently long-lasting to be harmful.
Should you take steps to thoroughly ventilate your home after new paint, carpet, etc. are installed? Absolutely. But the fact that your new paint, carpet, or pressboard desk is giving off a noticeable odor does not necessarily mean that you are being exposed to harmful levels of toxic VOCs, any more than smelling gas fumes while filling up your car’s gas tank means that you are suffering long-term harm by exposure to VOCs from gasoline.
What does all this mean for you?
First, despite the do-it-yourself kits available on the Internet, we strongly recommend that you do not attempt to install spray polyurethane foam yourself. This is an area where professional training and experience really do matter. Exposure during the installation process—to fumes from the spray stream or to irritating dust residues during “trimming” of excess hardened foam in a wall cavity—is possible.
It’s unfortunate that insulation contractors are not required to be licensed in Florida, but they aren’t. Tailored Foam’s insulation professionals have been called in on several occasions to diagnose problems with third party installations of foam insulation. Virtually every problem we have seen resulted from improper preparation and mixing of materials at the job site.
Tailored Foam of Florida is a state-certified general contractor. We have completed over 50,000 commercial and residential foam insulation projects since 1986, including insulation for Walmarts, schools, churches, hospitals and grocery stores. We believe we have installed more spray polyurethane foam insulation throughout Florida than all of our competitors combined. We have never had an issue with the health and safety of building occupants.
- Boric acid is not the same stuff as the ingredient in Borax® detergent, which is a salt-based product, not an acid. Our Core-Fill 500™ masonry foam insulation product contains trace amounts of boric acid, which is added to the aminoplast foam for pest control inside insulated concrete block walls.
- Dust is usually only produced after spray foam is applied to open wall cavities, during trimming of the excess hardened foam to produce a level finished surface. Affected rooms should be well ventilated after the installation process is completed.
- Allport, D.C., Gilbert, D.S. and Outterside, S.M. (Editors). 2003. MDI and TDI: safety, health and the environment. John Wiley & Sons, Ltd. Chichester, West Sussex, England. 2003. ISBN 0-471-95812-3.