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This guide explains the correct way to install roof drip edge metal along every eave and rake. The critical sequence: drip edge goes UNDER the underlayment at eaves (so water hits the metal and runs off), and OVER the underlayment at rakes (so wind-driven rain cannot blow under the felt). Pieces should overlap 2-3 inches with nails every 8-12 inches. The guide includes diagrams for hip roofs, valleys, and gable end transitions. Pair with our Drip Edge Calculator.
Drip edge is a simple L or T profile of metal along every eave and every rake. It costs very little and it prevents rot in the fascia and the sheathing edge — and it is required by the current residential code on new roofs and most reroofs.
The order, which is the whole job
At the eave: drip edge on the bare deck first, then the ice barrier and underlayment lap over the top of it.
At the rake: underlayment down first, then the drip edge over it.
That reversal is deliberate. It means water running down the underlayment reaches the eave drip edge and drips clear, and water running down the rake lands on top of the metal instead of behind it.
Getting it the wrong way round is the most common drip edge mistake, and it sends water behind the fascia.
Fitting it
Drip edge quantity by eave and rake length
Eaves + rakes
10 ft pieces at 2 in lap
With 10% waste
60 ft
7
7
100 ft
11
12
140 ft
15
16
180 ft
19
21
220 ft
23
25
Lap each piece over the next by about 2 inches, upslope piece on top.
Nail through the top flange onto the deck every 8 to 10 inches. Never through the visible face.
The lower lip should stand about half an inch clear of the fascia, so water drips rather than tracking back onto the wood.
Mitre or lap the corners properly. An open corner is a direct path into the fascia.
Which profile
Type C is a plain L and the cheapest.
Type D has a kickout at the bottom that throws water clear of the fascia — the better choice at eaves.
Type F has a longer top flange, used over existing roofing or at rakes where more coverage helps.
Aluminium is standard; steel lasts longer at more cost; copper only where the rest of the flashing is copper. Never put aluminium against copper.
On a reroof
Replace it. Old drip edge is bent, has nail holes in the wrong places and has usually been fitted in the wrong order anyway. It is one of the cheapest components on the roof and one of the easiest to get right while the covering is off.
Frequently asked questions
Does drip edge go over or under underlayment?
Under at the eaves, over at the rakes. That reversal is the whole point: water running down the underlayment drips clear at the eave, and water running down the rake lands on top of the metal rather than behind it.
How much drip edge do I need?
Add up every eave and every rake. Drip edge comes in 10 foot lengths lapping about 2 inches, so each piece covers roughly 9 feet 10 inches. Add 10% for cuts and corners.
How is drip edge fastened?
Through the top flange onto the deck, every 8 to 10 inches. Never through the visible face — a fastener there is a hole in the part that sheds water.
Should drip edge be replaced on a reroof?
Yes. Old drip edge is bent, has nail holes in the wrong places and has often been fitted in the wrong order. It is one of the cheapest parts of the roof to get right while the covering is off.