You can also check with a steel building supplier. I started reading about this stuff on this web site and was wondering the same thing, where the hell do I find this stuff? The I looked at the link posted in this thread and realized that I had a box full of this stuff left over from building my shop. They use it for sealing the corrugated roof panels on a pre-fab steel building. When I bought mine they gave me a huge box full of rolls, and I only used about 2/3 of it. I probably have 20 more rolls left! One of these days I'll actually take the time to strip everything off my deck and use it too!