How to Install Drip Edge Flashing on a Flat Roof
How to install drip edge flashing on a flat roof, the way Flat Roofers NY does it: fasten the metal edge over a sound deck edge, then strip the membrane in over its flange.
- Prep the deck edge.
- Measure and cut the metal edge.
- Nail it on the maker's pattern, joints overlapped.
- Strip in the membrane.
- Seal the laps.
Rather hand the edge to a crew?
The metal along your roof edge
- Drip edge
- Gravel stop
- Metal edge
Drip edge is bent metal with a lower leg that kicks out past the fascia. Gravel stop adds a raised lip at the top. "Metal edge" covers both.
Its job is runoff. It throws water past the fascia into the gutter. Without it, water curls under and wood rot starts at the deck edge.
Get the deck edge solid first
Press on the wood along the edge. Soft or rotted fascia and decking come out before any metal goes on.
Nails won't hold in punky wood, so replace the rotted fascia first.
- Metal edge pieces
- Roofing nails, or the fasteners your membrane maker calls for
- Sealant
- Cover tape or strip-in membrane
- Snips and a bending tool
Six steps along the edge
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Measure and cut
Cut lengths with snips, factory ends at the joints.
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Outside corners
Notch and fold the metal around the corner. Never butt-cut two pieces.
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Nailing pattern
Fasten through the flange at the manufacturer's spacing.
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Overlap joints
Lap each piece over the next by the amount the instructions give.
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Strip in the membrane
Run the cover strip over the flange onto the roof.
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Seal the laps
Finish every seam and corner per the membrane maker's sheet.
How each membrane ties into the metal
The tie-in changes with the roof system. Follow the membrane maker's sheet for yours.
| Membrane | TPOSingle-ply, welded | EPDMRubber roof | Modified bitumenTorched or adhered |
|---|---|---|---|
| Metal edge sits | On the membrane, or TPO-coated metal | On the membrane | Over the base ply, flange primed |
| Strips in with | Welded TPO cover strip | Cover tape | Torched or adhered cap ply |
| Laps sealed | Hot-air welded | Primer, lap sealant at tape edges | Torched or set in adhesive |
Cover tape is how an EPDM rubber roof ties into its edge.
On an older roof, tying new metal into existing bitumen needs a clean, primed surface first.
Edge leaks we trace to the install
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Membrane tucked behind the metal
Water runs straight in behind it.
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Fasteners off the pattern or too near the edge
So the metal lifts or splits.
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Butted joints with no overlap
They leave an open seam every length.
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Corners left without cover tape
Water finds that fold first.
Where the job stops being a weekend fix
Stop if rot runs into the deck edge. Stop if the old membrane is brittle and tears at the strip-in. Some membrane warranties also require an approved installer.
- Garage edgeOften a weekend job. Knowing how to install drip edge flashing on a flat roof gets you there.
- Three stories upRow houses, two-family homes, multi-family, mixed-use and small commercial buildings need a licensed, insured crew.
We do drip edge installation, edge flashing replacement and roof inspection. If the leak is really in the membrane or deck, that's a flat roof repair job.
Want new metal on your roof edge?
Need drip edge installed or worn edge flashing replaced in Queens? We'll check the edge and price it free.
Call Flat Roofers NY(917) 473-9811