Drip edge flashing on a flat roof keeps water from curling around the edges of shingles. Without drip edge flashing installed, water gets under the shingles and rots the sheathing, fascia and soffits. The drip edge also keeps water from dripping down the side of the home or building. Drip edge comes in many colours and is metal so you can paint it to match a home. You can also get galvanised drip edge flashing. Flat and sloped roofs follow the same steps for drip edge installation.
Begin at a corner of the roof and place the drip edge along the roof edge. The side with the flared edge hangs down in front of the fascia and the flat side sits atop the roof.
Nail or screw the drip edge flashing to the roof sheathing every 12 inches. Use a hammer for nails and an electric screw gun for screws.
Add the next piece by overlapping it over the previously placed piece by, at least, 2 to 3 inches. Nail or screw it down. Repeat this process all the way around the perimeter of the roof. The felt and shingles go over the drip edge.
Use a pair of tin snips to cut drip edge when shorter lengths are needed. This is common at the corners of the roof. Use an extension ladder to reach the high areas.
Use extreme caution when installing drip edge to avoid falling. If you cut the drip edge flashing, the edges can be extremely sharp.