Roofing Basics for a Drip Edge

Drip Edge Materials

• Steel and aluminum are the most common drip edge materials, and steel is arguably the most popular option. Although aluminum exhibits natural resistance to corrosion, steel is significantly stronger and a process called "galvanization" coats steel with rust-resistant compounds that greatly extend its expected life-span. Both aluminum and steel drip edge are available with dull, metallic finish or enamel of varying color.

Drip Edge Shape

• The primary component of drip edge is a long, narrow sheet of metal bent at a 90-degree angle near its center. The angle's interior fits over the edge of a roof's fascia, placing one side of the angle on top the fascia and the opposite side on the fascia's vertical face. The bottom edge of the drip edge's vertical side bends away from the fascia to form a small, angled lip or "edge." A common alternative design includes a second bend at the top of the drip edge's vertical side. The second bend allows the horizontally-oriented side of the drip edge to extend beyond the fascia's corner and support roof covering from beneath.

Installation Location

• Standard roofs consist of roof framing, such as rafters or trusses, a layer of sheathing, such as plywood, a layer of roofing paper and a roof covering material. Eaves are the horizontally level edges of a roof and gable ends are the sloped edges of a roof. Roofers typically install drip edge below roofing paper on eaves, and above roofing paper on gable ends. In other words, shingles rest on top of drip edge on a roof's gable ends. If fascia lines the roof's perimeter, roofers snug the drip edge against the upper corner of the fascia board.

Installation Procedure

• Roofers apply nails to the upper side of the drip edge; the side that rests on the roof sheathing or roofing paper. Roofers fasten roofing nails approximately every 12 inches. along the length of the drip edge. To install drip edge on an existing roof, roofers must slide the drip edge beneath the shingles and lift the shingles while fastening. Additionally, roofers sometimes apply roof sealant along the top side of the drip edge to cover nail heads and provide adhesion for shingles.