Understanding your result
The headline is the pieces of drip edge. The stats show the edge length, the nails and the number of corners. The breakdown splits the pieces between eaves and rakes, which matters because the eave pieces go on before the underlayment and the rake pieces after it, so they are often bought and installed on different days.
The number to remember is the edge to cover, eaves plus rakes, the same figure the starter strip calculator uses, because starter runs along every edge that has drip edge. Measure the perimeter once and use it for both.
If the roof has gutters, the eave drip edge should be T-style or a gutter apron, and the eave length here is the gutter length the gutter calculator starts from.
How we calculate this
The non-obvious part is the overlap. Pieces lap 2 inches by code, and the lap faces downhill on the rakes so water runs over the joint, not into it. Two inches on a 10-foot stick is only 1.7 percent, but with the corner mitres (each outside corner wastes a few inches of two sticks) the usual 5 percent allowance is right for a plain roof. A roof with many short eaves and rakes, dormers and returns, wastes more; set 10 percent.
Nails are at 12 inches on centre by the code, through the top flange into the deck, never through the vertical face. A roofing nail of the same metal as the drip edge avoids the galvanic corrosion that eats aluminum against steel. The drip edge and flashing guide shows the layering at eaves and rakes with the ice barrier and starter in place.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Stick length | 10 ft | Standard length of drip edge in US building supply; 12 ft sticks exist |
| Overlap | 2 in | IRC R905.2.8.5 (minimum 2 in lap at joints) |
| Nail spacing | 12 in on centre | IRC R905.2.8.5 |
| Nails per pound | 200 (1¼ in) | Approximate for 11-gauge roofing nails; the box states the count |
| Waste | 5% | Estimating practice for corner mitres and end cuts |
| Corners | 4 | Two eave-to-rake corners at each gable end of a plain gable roof; four eave corners on a hip roof |
| Profile | F-style | Standard for asphalt shingle roofs; T-style where gutters are fitted |
Assumptions last reviewed October 7, 2026.
The calculator does not count gutter apron for retrofits, the matching drip edge around dormers unless their edges are in the totals, or the drip edge on a flat roof (which uses gravel stop). It assumes the eave and rake pieces are the same profile; if you buy T-style for the eaves and L-style for the rakes, split the piece count as the table shows. The ice and water shield calculator handles the membrane that laps over the eave drip edge, and the standard sizes table lists stick lengths and the minimum laps for drip edge and trim.
Two worked examples
A gable house with 10-foot sticks
Two 40-foot eaves and four 18-foot rakes, F-style, 10-foot sticks, 2-inch lap, 5% waste, nails at 12 inches, four corners.
- Edge to cover: 80 + 72 = 152 ft
- With waste: 152 × 1.05 = 159.6 ft
- Effective piece: 10 ft − 2 in = 9.83 ft
- Pieces: 159.6 ÷ 9.83 = 16.2, rounded up to 17 pieces (about 9 for the eaves, 8 for the rakes)
- Nails: 152 + 2 × 4 = 160, about 0.8 lb
Seventeen sticks. Dividing 152 by 10 would have given 16 and left you one short at the last rake.
A hip roof with gutters, 12-foot sticks
A hip roof has no rakes. Its eaves total 140 feet; the eave profile is T-style for the gutters, in 12-foot sticks.
- Edge to cover: 140 ft (no rakes)
- With waste: 140 × 1.05 = 147 ft
- Effective piece: 12 ft − 2 in = 11.83 ft
- Pieces: 147 ÷ 11.83 = 12.4, rounded up to 13 pieces
- Nails: 140 + 8 = 148
Thirteen 12-foot sticks against seventeen 10-footers for a roof of similar size: longer sticks mean fewer laps and fewer joints to seal, at the cost of handling a 12-foot piece on a ladder.
Where to find your inputs
Eave length. Every horizontal bottom edge, including dormers and porches. On a gable roof, twice the house length plus the rake overhangs; on a hip roof, the whole perimeter at the drip line.
Rake length. The sloped edges at the gable ends: half the width plus the overhang, times the pitch factor, for each of the four rakes on a plain gable. The rafter length calculator gives it, or measure a rake board from the ground.
Profile. F-style for shingle eaves and rakes; T-style at eaves with gutters; L-style on rakes under metal roofing or where a plain angle is wanted. The supplier’s rack labels them.
Corners. Count the outside corners where two edges meet: four on a plain gable or hip roof, more with dormers, returns and L-shaped plans.
Common mistakes
- Dividing by ten. The overlap and the corner cuts cost a stick or two on a modest roof. Use the effective length.
- Eave and rake order reversed. Eave drip edge under the underlayment, rake drip edge over it. The guide shows the layering.
- Nailing the face. Nails go through the top flange into the deck. A nail through the vertical face is a hole in the drip line.
- Mixed metals. Steel nails in aluminum drip edge corrode the aluminum. Match the metal.
- Flush with the fascia. The lower leg should stand off the fascia by the width of the hem or the kick-out, so water drips clear instead of running back along the wood.
- Butting the pieces. Two inches of lap, with the uphill piece over the downhill one on the rakes. A butt joint opens as the metal expands in summer.
Questions people ask
- Is drip edge required by code?
- Yes for asphalt shingle roofs. The International Residential Code (R905.2.8.5) requires a drip edge at eaves and rakes, overlapped at least 2 inches where pieces meet, extending at least ¼ inch below the sheathing and 2 inches back onto the deck, and fastened at 12 inches on centre. Underlayment goes over the drip edge at the eaves and under it at the rakes.
- How many pieces of drip edge do I need?
- Add the eaves and the rakes, add 5 percent for the corner cuts, and divide by the effective length of a stick, which is its length minus the overlap: 9 ft 10 in for a 10-foot stick with a 2-inch lap. A gable house with 80 feet of eaves and 72 feet of rakes needs 159.6 ÷ 9.83 = 16.2, so 17 pieces.
- What is the difference between F-style and T-style drip edge?
- F-style (also called D-metal) has a long top flange and a hemmed lower leg, and it is the standard for shingle roofs. T-style has an extra kick-out that throws water further from the fascia, into the gutter; it is the better choice at eaves with gutters. L-style is a plain right angle used on rakes and under metal roofing.
- Does drip edge go under or over the underlayment?
- Both, depending on the edge. At the eaves it goes on the bare deck, under the ice barrier and underlayment, so water running down the underlayment drops onto the metal. At the rakes it goes over the underlayment, so wind-driven water on the metal cannot get under the felt. Mixing them up sends water behind the fascia.
- How many nails does drip edge take?
- The code spacing is 12 inches on centre, so roughly one nail per foot of edge plus a couple at each corner: 160 nails for 152 feet of edge with four corners, less than a pound of 1¼-inch roofing nails. Use nails of the same metal as the drip edge (galvanized with galvanized, aluminum with aluminum) to avoid corrosion.
- Can I install drip edge over existing shingles?
- Only with a profile made for it. Standard drip edge needs to sit on the deck under the shingles. For a retrofit at the eaves, a gutter apron slides under the first course of shingles and over the gutter; at the rakes the shingles must be lifted. The calculator counts pieces the same way for either.