If you're a professional builder or remodeler, you definitely want to invest in a foam gun. In this video, you'll learn more about the Great Stuff Pro Gun and the Great Stuff Pro Gaps and Cracks (foam). Matt Risinger shares a few pro-tips. The cured foam that comes out of the can is a closed cell foam. It's super rigid and doesn't expand that much when it comes out of the can. While the foam is not completely waterproof, it does create an airtight (and bug tight) seal. The foam is cured with water, so it sticks in those nooks and crannies. Bring a spray bottle of water along with you. A quick spray or two of water will get the job done. Before the drywall is installed, go around and use the spray foam to seal any penetrations, such as electrical outlets or exterior plumbing.Check out the full video to see the Great Stuff Pro Gun and foam in action.