I need to repair the big hole in a shingled roof that was left when an evaporative cooler was removed. The hole in the wood has been closed with boards. Next I need to patch the hole in the tar paper. How is new tarpaper attached? Presumably, on the upward slope, I put the edge of the new tar paper under the edge of the old tar paper. On the downward slope the edge of the new tar paper goes over the old tar paper. But what happens on the sides?