Drip edge flashing consists of angled thin strips of metal. It is installed on the edges of roofs before the shingles are put on. Drip edges cover the ends of eaves and rakes of houses and protect them from the elements. Drip edges can be made out of aluminium, galvanised sheet steel, copper, or flexible plastic. The thin metal or plastic drip edges are cut with tin snips and then bent at the cut point into an angled piece that is affixed to roof corners.
Measure the edges of the roof to determine length of the drip edge flashing and where to cut them to fit the corners. Draw a straight line on the top face of the drip edge trim with a felt tipped pen where it intersects a roof corner.
Measure the degree of the roof corner angle with a mitre angle tool. If it is less than 90 degrees, draw a V shape on the top face of the drip edge that is 1/2-inch wide, using the first mark as one side of the V.
Put on your heavy work gloves. Cut a slit into the top face of the drip edge on the marker line with the metal cutting shears or tin snips. If you drew a V shape, cut it out of the drip edge at this time.
Hold onto one side of the drip edge. Push the other side of the drip edge under its top face and bend the drip edge in a folding motion to make a corner piece.
To bend an internal corner, make an additional cut where the metal pops up when you bend it to allow the metal to bend without buckling on you.
Always wear gloves when working with fresh cut metal edges as they are extremely sharp.