Unless you’re a racing fan with really great vision, you probably haven’t seen this miracle in a can. Great Stuff spray foam expands as it cures — and, when cured, it’s tough, weatherproof, and bugproof. You can fill foundation cracks in old houses with this stuff, or just about any crack or crevice that needs filling. Just keep it in the back of your mind; you’ll know when you need it.
A 12oz. can runs about $5, and a 20oz. can goes for $8.