The flat roof on a garage rental properties had a bad section of wood. It was rotten. I cut, I removed and a piece of rotten wood 48 "x 32" with a piece of good wood is replaced. I cut the roll roofing a couple of inches beyond the cut of wood. Now I have to put some kind of roofing asphalt again to replace the rectangular piece of roll roofing that takes me. I have lots of plain white 3 tab shingles and lots of roofing felt, but roll roofing. Can you cut the tabs on plain white tiles and use the other parts along with some compound back to cover the wood in the hole that I fixed? Or should I break down and buy a whole roll of roll roofing although probably never use it all. After talking with others on the web, I found the answer. I would buy the roll roofing and that is designed for this purpose. You may, depending on code, cover with make your own pitch and asphalt work on it. That would probably be cheaper and last longer. But the tiles are a bad way to go, unfortunately.