On Friday morning before Labor Day, the insulator came to blow in sucrose-based spray foam insulation in our kitchen and dining room floors. Spray foam is apparently the next big thing in insulation. It creates a much tighter seal than fiberglass batts ever could, by starting out as a liquid then expanding to fill in every nook and cranny of your old, drafty house.
Proponents of spray foam say it will seal up your house’s envelope so tight you can expect to see up to a 50% reduction in your heating expenditure. (I hesitate to simply say “heating bills,” because I like to think green building is as much about conserving resources as it is about saving money.) It has an R value of some pretty high number, like R-21, I think. Detractors say you have to be careful when calling spray foam insulation green, because it is a petroleum-based product. But because our house is so old, it has smaller than average stud bays, which means the contractor would have had to build out the framing on the house by up to 2 inches, all over the house, to make standard blown-in cellulose insulation have the proper R-value. So you I suppose one could argue that by using the spray foam, we’re saving trees by saving on the lumber we’d need to do all that extra framing.
Anyway, spraying this stuff is a pretty big job. The insulator parked a truck outside our house, ran a thick hose through the front door, and suited up in a pretty serious-looking spacesuit. The fumes, I have to say, did not smell pretty.
Spray foam insulation truck
Ben, our contractor, told us that according to the insulator, 99.9% of the petroleum product off-gasses within the first 24 hours, so indoor air quality is relatively unaffected. The petroleum base of the insulation is mixed with either soy or sucrose, in varying percentages, which means some formulations are more “green” than others.
To be honest, we don’t know how much sucrose and how much petroleum is currently insulating our floors. We do know that in previous years the winter air in the crawlspace underneath the kitchen must have made winter mornings pretty darn cold.
Spray-in foam insulation
The subfloors in the kitchen and dining room should be down soon, and will cover up all that pretty green foam. Once the carpenters finish the interior framing, the insulator will come back to fill up the stud bays in the walls.
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