I used this on my roof to keep debris from getting under roof tiles and causing water to pool and then leak. It goes on just like the video demo. It was flexible enough to seal up greatly uneven tile junctures. I will probably use it on my chimney next, It hardens up nicely and seems very secure. I used a 2-part product a few years ago and it was a mess. Flash Seal is an easy one-step process that I wish I had used instead. I recommend it highly.