How should drip edge be installed, and when?
Short answer. Drip edge is installed at the start of a roof job: eave pieces nail onto the bare deck before any underlayment, and rake pieces go on after the underlayment is down. Each piece is held snug to the fascia, nailed every 12 inches or less high on the roof flange, overlapped at least 2 inches, and notched and folded at the corners.
Tools and materials
Tin snips, a hammer or nail gun, corrosion-resistant roofing nails, a chalk line and enough drip edge to cover every eave and rake plus overlaps. Pieces commonly come in 10-foot lengths in aluminum or galvanized steel.
Step by step
- Check the fascia. Replace soft or rotted boards first. Metal fastened over rot fails with the wood.
- Start at the eaves. Set the first piece at one end with the drip leg hanging just off the fascia, aimed into the gutter if there is one. Nail high on the roof flange where the shingles will cover the nails.
- Lap the next piece. Overlap at least 2 inches and keep the line straight. Snap a chalk line on long runs.
- Fold the corners. At an outside corner, cut a tab into the eave piece and bend it around the corner so there is no open gap.
- Dry in. Roll leak barrier or underlayment over the eave flange, then run underlayment up the rakes.
- Install the rakes bottom to top. Each upper piece overlaps the one below it, and the lowest rake piece laps over the eave corner.
When to install it
The best time is during a full roof replacement, when the old metal comes off with the shingles. Drip edge can be retrofitted on an existing roof by sliding it under the first course, but the underlayment at the eave ends up beneath the metal instead of over it, so a retrofit is a partial fix rather than a true one. For how the profiles differ and what each one does, read drip edge explained and see where it fits in roof anatomy explained.