Roof flashing is needed as protection when the roof planes butt up against vertical walls at the end of each shingle course. These rectangular pieces of metal flashing are approximately 10 inches long and at least 2 inches wider than the face of the shingle being used. The 10-inch length is bent in half so that 5 inches will reach up the wall surface and the other half will extend onto the roof deck. Step flashing is placed on the first row of shingles against a vertical wall or structure. Embed