Dear EarthTalk: The cold winter we’re having here in the Northeast has convinced me to finally beef up my home’s insulation, but I’ve heard that spray foam can off-gas noxious chemicals and pollute the indoor environment. Are there safer options? — Rose Donahue, Framingham, MA
Making your home more energy efficient is certainly good for the planet and will cut your heating/cooling bills, but you’re right to worry about chemical off-gassing. According to the non-profit Environmental Working Group (EWG), most common spray polyurethane foam insulation contains methylene diphenyl diisocyanate, or MDI, a synthetic chemical that has been linked to asthma, lung damage and even death.
“Because of the chemical’s risks, the federal Occupational Safety and Health Administration has set the maximum legal limit for MDI exposure among workers who handle it and related chemicals at 0.02 parts per million in workplace air,” reports EWG. “However, independent contractors and the general public, including homeowners who take on DIY insulation projects, may not be aware of these federal regulations or the risks associated with MDI exposure.”
In 2011, the U.S. Environmental Protection Agency (EPA) announced that it was studying whether to regulate, restrict or even ban MDI in consumer products. (MDI is also used in a variety of adhesives and coatings like Gorilla Glue.) “Four years later, the agency has yet to take real action to protect ordinary people who go to their local hardware store and pick up a product that contains MDI,” adds EWG.
There is hope from the West, though, as the state of California has made finding safer alternatives to MDI a priority in its Safer Consumer Products program, which requires manufacturers to look for greener, healthier alternatives. Time will tell if this new initiative in California will move manufacturers there and elsewhere away from MDI. Meanwhile, EWG wants the federal government to step up on the issue and restrict or ban MDI insulation across the country.
Homeowners willing to spend a little extra do have some safer alternatives to polyurethane spray foam at their disposal. Soybean-based spray foam doesn’t rely on MDI or any other synthetic chemicals but has a similar R-value (measuring the strength of the insulation in blocking air) as conventional spray foam. Leading soy-foam manufacturers include Biobased and Demilec. Castor oil-based Icynene is another chemical-free spray foam alternative great for green-minded home renovators.
Cotton denim batting—typically made from recycled scraps from denim factories—is another healthy alternative, but can’t be sprayed in and costs almost twice as much in material costs as spray foam. Sheep’s wool insulation is another effective choice, but also can’t be sprayed in and costs significantly more than foam. These and other greener insulation options are available at mainstream and specialty home improvement stores, and also online via vendors including Green Depot, Green Home Solutions and Green Building Supply.