What size drip edge does my roof need?
Short answer. Size drip edge to your roof edge, not the size of the house: the face has to cover the top of the fascia and extend at least 1/4 inch below the sheathing, and the flange has to reach at least 2 inches onto the deck. On a typical Georgia home with a standard fascia board and gutters, a common drip edge or gutter apron with about a 2 inch flange works, while thick or built-up edges need a longer leg.
Measure the edge
- Deck thickness. Look at the edge of the sheathing. Most is 7/16 to 5/8 inch, but some edges have an extra layer or a sub-fascia.
- Gap to the fascia. Note any space between the deck edge and the fascia board. The drip edge face has to bridge it and still lap over the fascia.
- Fascia position. If the fascia sits low relative to the deck, you need a longer face to reach past the top of the board.
- Gutter mounting. If gutters hang tight under the drip edge, the face and kick have to work with the gutter's back edge.
Pick the size
- A face long enough to cover the deck edge and gap, overlap the top of the fascia, and still project at least 1/4 inch below the sheathing.
- A roof flange of at least 2 inches. Wider flanges give more lap under eave membrane.
- On re-roofs where the old edge is built up, an extended or long-leg profile.
Count the pieces
Measure every eave and rake in linear feet and add them up. Drip edge comes in 10-foot lengths, and each piece covers a little less after the required 2-inch lap. For example, 200 feet of edge needs about 21 pieces before waste, so add one or two for corners and cuts.
Fastening
The code calls for fasteners no more than 12 inches apart, using the same type of roofing nails specified for the shingles.
See profiles in drip edge explained and how roofers take edge measurements in how roofers measure a roof.