Closed-cell spray foam
We are considering putting closed cell spray foam based in our unvented crawl space based on an energy audit. I got a second quote and the numbers vary wildly and the only difference is the depth of the foam (which makes sense more foam = $). How do I know what is the correct thickness of foam? One quote is for 2 inches on the ceiling and 1.5 inches on the walls and the other is for 3 inches on both. I don’t want to waste money on 3 inch if it isn’t necessary but I don’t want to not see a significant change due to too little spray foam being used. We are in Long Island NY.
Thank you in advance.