Roof Drip Edge Installation: A Step-by-Step Guide
A missing or badly installed drip edge is one of the fastest ways to turn a healthy roof into a rot problem. Water sneaks behind the fascia, soaks into the roof deck, and by the time you see a stain on the ceiling, the damage has been happening for months. Roof drip edge installation looks simple, but the order of operations relative to your underlayment and the fastening pattern you use make the difference between a roof that sheds water correctly and one that quietly feeds it into your walls.
This guide walks you through exactly how to do it right: where drip edge goes at the eaves versus the rakes, how it should overlap with your underlayment, and which fasteners actually hold up through a Washington winter. We'll cover the sequencing question that trips up most DIYers, plus the corner laps and nailing spacing that inspectors look for.
We've installed drip edge on hundreds of homes across Kirkland, Bothell, and the greater Seattle area, and we've fixed just as many jobs where a shortcut here caused a fascia replacement two years later. If you're tackling a drip edge roof installation yourself or just want to confirm your contractor got it right, this step-by-step breakdown gives you the details that matter.
What you need before installing a drip edge
Getting drip edge installation right starts before you ever climb a ladder. Material choice matters more than most homeowners realize, since aluminum, galvanized steel, and copper all behave differently under fasteners and against the elements. Aluminum drip edge (typically .019 to .032 inch thick) resists corrosion well and costs less, but it dents easily if you're not careful with a hammer. Galvanized steel holds its shape better during installation and stands up to impact, though it needs a factory coating to prevent rust in our wet Pacific Northwest climate. Copper looks great and lasts decades, but the price tag only makes sense on high-end architectural projects.
Material | Thickness | Best For | Approx. Cost/10ft |
|---|---|---|---|
Aluminum | .019"-.032" | Most residential roofs | $8-$14 |
Galvanized steel | 26-29 gauge | High-wind or impact areas | $10-$16 |
Copper | 16-20 oz | Premium/architectural | $35-$60 |
Beyond the drip edge itself, gather roofing nails rated for exterior use, specifically 1-1/4 inch corrosion-resistant nails with a large head. Don't substitute standard drywall or framing nails; they'll rust and stain your fascia within a season. You'll also need aviation snips for cutting corners, a chalk line for keeping runs straight, and a hammer or pneumatic roofing nailer if you're covering more than a couple hundred linear feet.
Check your local building code before you buy materials, since requirements vary by jurisdiction. The 2021 International Residential Code, which Washington state has adopted with amendments, specifies drip edge at both eaves and rakes with a minimum 2-inch overlap at seams and fasteners spaced no more than 12 inches apart. You can review the full requirements through the International Code Council, but your local Kirkland or King County building department can confirm any local amendments before you start.
Skipping the overlap or fastener spacing specs isn't a cosmetic shortcut, it's the difference between passing inspection and reroofing in five years.
Finally, measure your roofline accurately. Add 10 percent to your linear footage total to account for overlaps and waste from cutting corners. If your eave measurement comes to 120 feet and your rakes add another 80 feet, you're looking at roughly 220 feet of drip edge before waste, so round up to at least 240 feet of material.
Step 1. Install drip edge at the eaves
Start at the eaves, since this is where the sequencing question actually matters. Eave drip edge installation happens before you roll out underlayment, not after. The metal goes directly on the bare roof deck, tight against the edge, so that any water running down the underlayment later drains onto the drip edge and off into your gutters and downspouts instead of wicking back under the fascia board.
Position the drip edge so it overhangs the fascia by 3/4 inch to 1-1/2 inch, then check that the vertical leg sits flush against the fascia face with no gaps. Snap a chalk line first if your roofline isn't perfectly straight, since even a quarter-inch wander becomes obvious once shingles go down.
Drip edge goes under the underlayment at the eaves and over it at the rakes; reverse that order and you've built a water trap into your roof.
Nail it down using this pattern:
Drive roofing nails every 12 inches along the top flange, never through the vertical face.
Keep nails at least 1 inch from each edge of the metal to avoid splitting or bending it.
Overlap each piece by a minimum of 2 inches at the seams, and run a bead of roofing sealant underneath the overlap in coastal or high-wind areas.
Set fasteners snug but not crushed; overdriving an aluminum nail head can dimple the metal and create a spot where water pools.
Once the eave run is nailed off, roll your underlayment for asphalt shingles down over the top flange so it laps onto the drip edge by at least an inch. That overlap is what actually keeps water moving toward the gutter instead of finding a seam to exploit.
Step 2. Install drip edge along the rakes
Rake edges work the opposite way from eaves, and this is where most DIY installs go wrong. Rake drip edge installation happens after the underlayment goes down, not before. You're installing the metal on top of the felt or synthetic underlayment along the sloped edges of the roof, so water shedding off the roof surface lands on the drip edge and drips clear of the fascia instead of running underneath it.
Start at the bottom of the rake near the eave and work your way up toward the ridge. Overlap each new piece over the one below it by at least 2 inches, matching the direction water flows so gravity never finds a gap to work through. The drip edge should overhang the fascia the same 3/4 inch to 1-1/2 inch you used at the eaves, and the vertical leg should sit tight against the fascia face for the full run.
Rake drip edge sits over the underlayment, eave drip edge sits under it, and mixing up that order is the single most common installation mistake we see on inspections.
Fasten it with the same spacing discipline you used on the eaves:
Nail every 12 inches along the top flange, keeping fasteners away from the vertical face.
Stay at least 1 inch in from each edge of the metal.
Add extra nails near the ridge and eave transitions where wind uplift is highest.
Where the rake meets the ridge at the top of the roof, trim the drip edge flush rather than letting it run past the peak. A clean, tight cut here keeps your ridge cap or ridge vent installation simple and avoids a metal edge poking out where it doesn't belong.
Step 3. Cut and fold corners for a clean fit
Corners are where a rushed drip edge installation shows itself fastest. Every eave-to-rake transition needs a mitered corner cut so the two pieces overlap cleanly instead of butting into a gap that funnels water straight behind the fascia. Grab your aviation snips and cut the horizontal flange at a 45-degree angle on the piece running along the eave, matching the angle of the roof corner exactly.
Once you've made the cut, fold the vertical face of the eave piece around the corner so it wraps snugly against the rake fascia, then overlap the rake drip edge on top by at least 2 inches. This fold-and-lap method keeps a continuous metal barrier at the single spot on your roof where three water paths converge: eave runoff, rake runoff, and whatever wind-driven rain hits the corner directly.
A sloppy corner cut is a small mistake with a big consequence, since that one gap is exactly where fascia rot starts.
Work through corners methodically:
Dry-fit the pieces before nailing anything, checking that the overlap sits flat with no bowing.
Crimp the fold with pliers or a seaming tool rather than just bending it by hand, since a crisp fold sheds water better than a rounded one.
Run a bead of roofing sealant under the corner lap before nailing it down, even if you skipped sealant elsewhere.
Nail both flanges within an inch of the corner to lock the fold in place, then continue your normal 12-inch spacing down the run.
Check the finished corner from underneath if you can access the eave. You should see a solid metal fold with no visible daylight or gap where the two pieces meet.
Step 4. Replace drip edge on an existing roof
Replacing drip edge on a roof that's already shingled means dealing with tear-off, not a clean deck. Existing drip edge replacement almost always happens alongside a full or partial reroof, so it helps to know what an asphalt shingle roof replacement costs before you start, since you can't slide new metal under existing shingles without damaging them. Start by pulling the first two to three courses of shingles back far enough to expose the old drip edge and underlayment underneath.
Once exposed, pry out the old fasteners with a flat bar rather than yanking the metal loose, since ripping it out can tear the underlayment you're planning to reuse. Inspect the roof deck edge for soft spots or rot while it's exposed; this is often the only chance you'll get to catch fascia damage before it's covered again. If you find soft wood, replace that section before installing anything new. Fascia rot inspection at this stage saves you from redoing the whole job in two years, and rotted boards are worth handing to an exterior trim repair pro while the edge is open.
Tear-off is the one moment you can actually see what's been happening behind your old drip edge, so don't rush past it.
Work through the replacement in this order:
Remove old drip edge and inspect the deck edge and fascia for damage.
Install new drip edge following the same eave-under, rake-over sequencing as a fresh install.
Patch or extend the underlayment so it still laps correctly over the new metal.
Reinstall shingles starting from the course you pulled back, keeping nail lines intact and following the same step-by-step asphalt shingle installation you would on a new roof.
You'll get the cleanest results if you treat this like a mini version of the full roofing installation process rather than a quick patch job.
Getting the small details right
Drip edge installation isn't complicated, but it's unforgiving. Get the sequencing right (under the underlayment at the eaves, over it at the rakes), keep your fastener spacing tight at 12 inches, and lap every seam and corner by at least 2 inches, and you'll have a roof edge that sheds water for decades instead of quietly rotting your fascia behind the scenes.
Most of the failures we see on inspections trace back to one of these small details getting skipped under time pressure. A missed overlap, a nail driven through the vertical face, a corner folded instead of cut and lapped properly. None of these mistakes show up right away, which is exactly why they're dangerous.
If you'd rather have a crew that's done this hundreds of times handle it correctly the first time, book a no-cost roof inspection in Kirkland, Bothell, or Bellevue and we'll check your drip edge, fascia, and underlayment before small problems turn into expensive ones.
