Air Sealing Without Foam? Can We Replace 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...

If you've ever held a Styrofoam cup comfortably in your hand, only to scorch your tongue sipping the piping-hot coffee inside, you know that plastic foam is a really good insulator. It's also lightweight, generally impervious to moisture, relatively cheap, and strong. With all that in its favor, it would take some effort to find a contemporary, high-performance building that doesn't incorporate foam insulation into key parts of its assembly. But a dark side to foam has come into focus over the last decade. To name a few issues, its manufacturing process can be polluting, its global warming impact can be stratospheric, it is laden with toxic flame retardants, and it is highly flammable, even with those chemical additives...