Air-Sealing Without Foam

When it comes to air-sealing, canned spray foam is often seen as the perfect material for plugging medium-sized holes and gaps, mostly because it's inexpensive and easy to apply. I've used a lot of canned foam for air-sealing over the years, and I even wrote a JLC article that described some of my methods for working with it and other sealants ("Air-Sealing Tips and Tricks," 1/12).

But as time passed, I began to have questions about canned foam's durability. I noticed in particular that pipes and wires would often break loose from the surrounding foam. I dissected foam samples and studied the material's fragile structure under a microscope. My conclusion is that air-sealing a building with canned foam may provide an...