We're going to have to start choosing a lot of building materials for the Bennett House shortly. There's heating systems, insulation, exterior wall facing, roofing, windows, and flooring to start us off. It's a lot to research in terms of comparing products and prices. Insulation has been a thorn in my side since we applied for our permits. I originally didn't put that much thought into it and just took the advice of Gigi, our contractor and others and specified BASF closed cell spray foam insulation for our permit application.
It has the highest R value of all the insulation products out there and is really being marketed as a bit of a wonder product. Higher R value means a better insulated home, means better energy efficiency. The one thing that kept niggling away at me however, is that it is still a petrochemical product that has the potential to off-gas-- plus it is practically fused to your home once it is installed so would be hell to remove if a problem did arise. Once I looked into it further I decided that I really don't know if I want to use this product in our home.
Spray foam is formed as a result of a chemical reaction between two fairly toxic substances. An A-side (isocyanate) and a B-side (polyol plus other additives) along with a blowing agent. When it is installed correctly there is supposed to be an immediate chemical reaction between the 2 sides that forms an inert, solid insulating mass. The majority of problems that people have (and there are horror stories all over the internet) seem to occur when the installation is done improperly. Either the spray is done too thick, or there is not an equal amount of A side to B side. But it worries me enough. Especially when it is approximately 3 times the cost of traditional insulation!
So I've been researching "greener" options and came across this:
Ultra Touch Denim Insulation by Bonded Logic. It has zero VOC's, is mould and fire resistent and it is made from re-cycled blue jeans! Well actually it is mostly made from the offcuts from denim manufacturers that were otherwise going to landfill, but still very interesting. You can't get this stuff in The Home Depot, but I managed to find a distributor in the Toronto area -- Eco-Building Resource. They quoted me $1.50 per sq. ft. for R21 (based on our total square footage). Definitely more expensive than fiberglass or mineral wool, but not nearly as expensive as spray foam. The only downside to this insulation (other than cost) is that it seems to absorb water like the Dickens! I did a little test on my sample and it soaked in the water, matted down the fibers and stayed wet for over a day. This kind of concerns me. I'm not expecting any leaks in our walls, but from what I understand, moisture is always something to consider in a home. Hopefully a good vapour barrier will deal with any potential problems.
Mineral wool insulation is the other option I am thinking about. It is made from spun basalt rock fibers, is relatively cheap, impervious to water (although I didn't test it myself), and fire resistant. The big downside to mineral wool (Roxul is one manufacturer located in Milton) is that they use formaldehyde as a binder. Some of my research shows that there is actually quite a lot of formaldehyde in this insulation. Bummer! There doesn't seem to be any perfect insulation out there! One suggestion was to let the Roxul "breathe" for approximately 2 weeks before installation to let it off-gas. This should, along with a good vapour barrier, keep the formaldehyde out of the indoor air. Not sure if I'm all together comfortable with this either. And with this logic, we could go back to the spray foam and use a good tight vapour barrier as well. Who would have thought there would be so much to think about!