A conversation I had with a Realtor today reminded me to discuss the trend toward Spray Foam Insulation in attic spaces. We decided that neither of us is a fan. Yes I know, I have touted the benefits of recent advances in residential building tech, but this one is a ‘no go’ for me. Instead of blown in or Batt insulation on the attic floor and ventilated roof structures, a chemical mixture is sprayed directly onto the roof deck that expands to the correct thickness depending on material type. There are two; open cell foam and closed cell foam. Without getting into the weeds about it, one is better for 4 season or cold climates and the other for temperate or hot climates like ours. With both types, any structural ventilation is eliminated with one exception for extremely cold climates. The attic is essentially a sealed envelope. There is anecdotal evidence regarding defective mixture of the chemicals on site that cause toxicity. The more they spray the closer we will get to major litigation in the future regarding respiratory issues. Just my opinion, not fact. I can’t speak to the performance of spray foam in a 4 season or cold climate but here in the Southwest, I believe it is a mistake to not ventilate attic spaces. My other issue is that with the number of leaking roofs I report on weekly, it is a bad idea to cover all the areas where roof leaks can be easily detected and not covered by several inches of foam that will hide the issue for a long time. Ripping out foam insulation to repair water damaged roof decking will be a nightmare and replacing the foam will be expensive. YouTube has some interesting videos regarding toxicity issues and the debate about ventilation. Definitely check these out if your considering a new build with spray foam.