Flashing Shingle Installation on a Roof Edge

Match the Roof

• Roof edging should match the style and pitch of the roof. Flat or low slope roofs and steeply pitched roofs need different edging. It also should be matched to the type of roofing; asphalt shingles and tiles, for instance, need very different types of edging. In addition, it should be combined with effective guttering to drain water away from the roof edge.

Basic Edging

• The basic type of drip edge is a 90-degree metal strip with one side that goes on the roof, and a bent edge with a lip at the bottom that goes down the side of the facing or trim board. The bent strip seals the roof and the lip pushes water into a gutter. This style can be installed on either the eave at the bottom of a roof slope or on the rake, the angled edges on a gable roof.

P and C Edging

• Other styles of drip edge are P-shaped and C-style. A P-shaped drip edge extends beyond the edge of the roof, then is bent back to the fascia so it forms a sort of "P." C-style is used on roofs with no fascia or trim board; it goes over the edge of the roof, then back under the decking so the edge is totally sealed from moisture.

Installation

• Drip edge is installed first at the bottom or eave of the roof and nailed into place with roofing nails. A bead of roofing cement is frequently applied at the top to further seal it. Roofing paper or underlayment membrane is installed over that drip edge. Rake edge, along the slopes of a gable roof, is installed over the underlayment to prevent it from blowing in wind. This also may be sealed with roofing cement.

Tile and Metal

• Roof tiles and metal roof panels also need edging, but these are matched to the specific roofing material and are usually supplied with those materials. Installation is similar, along the eaves and rakes of a roof.