Drip edge: what it is, where it goes, and how the code says to install it
Drip edge is the bent metal strip along a roof's edges that carries water off the edge and past the fascia. The code calls for it at the eaves and rakes of every shingle roof, lapped 2 inches, reaching at least 1/4 inch below the sheathing and 2 inches back onto the deck, and nailed every 12 inches or closer. Underlayment goes over the drip edge at the eaves and under it at the rakes (IRC R905.2.8.5).
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What drip edge does
Drip edge is a strip of bent metal along the edges of the roof deck. Its top leg lies on the deck under the roofing; its lower leg turns down past the edge of the sheathing, so water running off the roof drips clear of the fascia instead of curling back under the shingles and into the wood. On the eaves it sends the water into the gutter. The guide to the parts of a roof shows it at the eave.
The code’s rules
For shingle roofs, the residential code calls for drip edge and sets how it goes on (IRC R905.2.8.5):
| Rule | What the code says |
|---|---|
| Where | At the eaves and the rake edges |
| Laps | Pieces overlap at least 2 inches |
| Reach down | At least 1/4 inch below the roof sheathing |
| Reach back | At least 2 inches onto the roof deck |
| Nailing | Fastened to the deck at 12 inches apart or closer |
| Underlayment | Over the drip edge along the eaves, under it along the rakes |
The eaves are the level edges at the bottom of the roof; the rakes are the sloped edges at the gable ends. The guide to the rake shows which is which.
Which goes first, drip edge or underlayment
It depends on the edge:
- Eaves: drip edge first, then the underlayment laid over it, so water on the underlayment runs out over the drip edge.
- Rakes: underlayment first, then the drip edge over it.
Where an ice barrier is required, it starts at the eave too (IRC R905.1.2).
How much drip edge a roof needs
Add up the eaves and the rakes, then a little for the 2 inch laps. A simple gable roof on a 40 by 30 foot house has two eaves of about 40 feet and four rakes; the roofing calculator gives the eave and rake lengths for any roof, with the drip edge in the list.
Common questions
Is drip edge required?
On shingle roofs under the residential code, yes: at the eaves and the rakes (IRC R905.2.8.5). Your local code is the one that applies.
Does drip edge go under or over the underlayment?
Under it at the eaves, over it at the rakes.
Does drip edge go behind the gutter?
At the eaves, the drip edge’s lower leg sends water into the gutter, which hangs just below it on the fascia. The guide to installing gutters covers the gutter.
Is drip edge on a roof estimate?
Yes, as a line of its own priced by the linear foot of eave and rake.