Never, never, never allow anyone to work on your home without a written contract that includes the contractor's license number on it and his signature. The contract doesn't have to be fifty pages to show what is agreed upon, what it will cost and what the warranty is. Any businessman worth hiring will not have a problem providing this (to cover himself as well as you). The very best thing you can get from doing this is that if a man gives a license number and he doesn't have one in fact, he faces CRIMINAL charges so has a vested interest in being up front with his promises. Call your state consumer affairs office for advice. Good luck, kizmet.