Working with Denim Insulation

Insulation isn't sexy -- CFLs, solar panels, green roofs, those get all the green love. But there are some interesting green insulation options, like soy-based spray foam, and denim batts. Better insulation and sealing of houses is the 'low-hanging fruit' of energy-efficient homes. We need more efficient and affordable solar and other technological innovations, but the most cost-effective place to start is sealing the building envelope. That's been an ongoing project here, since even before the addition. When I moved into the house, there was almost no insulation.

I hadn't worked with denim insulation before, but I'm always interested in greener options. After using up the rest of the traditional R-19 roll I had, I got some UltraTouch. It's made from recycled denim (post-industrial waste) and so has a lovely blue color.

The first thing I discovered is its hecka dusty. Most batt insulation gives off some dust (plus it's all very good at absorbing dust wherever it is.) Usually it's not-good-for-you fiberglass fibers it's giving off. But when I was stuffing the denim batts between the floor joists, I observed a veritable storm of dust coming down. After putting up a couple of batts, there was a visible blue layer on top of the washing machine.

The second thing I discovered is that its hard to cut the usual way (i.e., with a utility knife or a pair of scissors). The UltraTouch website suggests a $30 Cepco insulation knife, a Bosch Foam Rubber Cutter, a hand held grinding tool, or a table saw. Huh? OK, they all make some sense, but I'm too cheap too frugal not ready to buy a special tool just to work with insulation batts. And my table saw blade doesn't come out nearly far enough to cut a batt of R-19. So I read a little closer, and noticed it also mentions using a circular saw with the blade reversed. At least with the circular saw you can easily compress the insulation as you cut it. I put my cement and Hardiboard blade on instead of reversing my regular blade, and it works quite nicely. I also found a little handsaw works pretty well for making those little partial cuts you need for getting insulation around a pipe or wire.

Despite the dust and the increased difficulty cutting it, my vote so far is a big thumbs up. The blue dust is much preferable to fiberglass fibers, and the cost was comparable to traditional batts.

Have any of you worked with denim insulation? What's your experience been?