A flat roof drip edge is perimeter edge metal that carries runoff clear of the fascia and locks down the membrane along a low-slope roof, and it works nothing like the drip edge on a shingle roof. On a pitched roof the drip edge slips under or over the shingles. With drip edge on a flat or low-slope membrane roof, the metal goes down first and the membrane laps over it, so the water path, the fasteners, and the wind rules are all different. Get the lap direction wrong and the edge becomes the first place the roof leaks. On low-slope roofs under 2:12, Section 1504.6 of the 2021 International Building Code requires the metal edge to pass ANSI/SPRI ES-1 wind tests RE-1, RE-2, and RE-3.
Reviewed by The Roofing Brief Team. Last reviewed: October 2026.
What is a flat roof drip edge?
A flat roof drip edge is an L-shaped or T-shaped metal flange, usually aluminum or galvanized steel, fastened around the perimeter of a low-slope roof to shed water past the fascia and to anchor the membrane edge. It sets the finished edge line, protects the wood fascia and roof deck from rot, and on ballasted or gravel systems it holds the aggregate in place. Roofers also call it edge metal, edge trim, fascia metal, or a gravel stop, depending on the profile. A typical manufactured example, the Metal-Era One Drip Edge, is 24 gauge steel clad in TPO or PVC, ships in 10 or 12 ft lengths with a 22 gauge galvanized continuous cleat, and is tested to ANSI/SPRI/FM 4435/ES-1.
The core job is water control. The horizontal flange bonds to or clamps the membrane, the vertical face covers the fascia, and the hemmed lower lip forces water to drip away from the wall instead of running back underneath. The flange sits on a wood nailer: the Elevate RubberGard EPDM Design Guide (July 22, 2026) requires nailers at all roof edges, at least 1/2 inch wider than the metal flange on the roof side, fastened to resist 200 lb per lineal foot in any direction.
Flat roof drip edge vs shingle drip edge: the key difference
The difference is lap direction and what secures it. On a shingle roof, 2021 International Residential Code Section R905.2.8.5 puts the underlayment over the drip edge at the eaves and under it at the rakes, extends the metal at least 1/4 inch below the sheathing and 2 inches back onto the deck, laps pieces 2 inches, and fastens them at 12 inches on center or closer. On a flat membrane roof the edge metal is set first and the membrane is carried over the top flange and welded, taped, or clamped to it, so the waterproofing sits above the metal.
| Detail | Shingle roof drip edge | Flat roof drip edge (edge metal) |
|---|---|---|
| Governing standard | IRC R905.2.8.5 (drip edge required) | ANSI/SPRI ES-1, via IBC 2021 1504.6 (1504.5 in the 2018 IBC) |
| Lap order | Underlayment over metal at eaves, under metal at rakes | Metal first, membrane laps over the top flange |
| What secures the edge | Roofing nails, shingle overhang | Cleats or fasteners plus membrane strip-in or a termination bar |
| Primary failure mode | Fascia rot, ice damming at eave | Wind uplift peel and membrane pull-off at the corner |
| Typical profile | Type C, Type D (hemmed L) | Drip edge, gravel stop, coated (clad) metal |
Types of flat roof edge metal
Flat roof edge metal comes in a few distinct profiles, each matched to the roof system and the surfacing. A drip edge sheds water, a gravel stop also dams loose aggregate on built-up roofs and on ballasted roofs (which IBC 2021 1507.12.3 limits to slopes under 2:12, with stone to ASTM D448 or D7655), and coated metal lets a welded TPO or PVC membrane bond straight to the flange.
| Profile | What it does | Best for |
|---|---|---|
| Standard drip edge / fascia metal | Hemmed lower lip sheds water past the fascia; covers the edge board | EPDM, TPO, PVC, mod-bit edges without ballast |
| Gravel stop | Raised vertical leg holds back gravel or ballast and stops washout | Built-up (BUR) and gravel-surfaced or ballasted roofs |
| Coated (clad) metal | TPO- or PVC-laminated flange the membrane heat-welds directly onto | Fully welded TPO and PVC systems for a monolithic edge |
| Termination bar plus counterflashing | Bar clamps the wrapped membrane; a drip cap covers the fasteners | EPDM edges, wall transitions, retrofit tie-ins |
| Canted / drip cant | Sloped face at the edge to break the angle and speed drainage | Roofs with parapets or edges prone to ponding |
Gravel stop vs drip edge: which edge for which roof
Gravel stop vs drip edge comes down to surfacing and wind exposure. Use the thresholds below, drawn from IBC 2021, IRC 2021, and maker data, then confirm the exact profile against the membrane maker’s edge detail, since that is what the warranty is written against.
| If the roof edge | Use | Source |
|---|---|---|
| Carries loose gravel, BUR aggregate, or stone ballast | Gravel stop with a raised leg | IBC 2021 1507.12.3 (ballasted roofs under 2:12) |
| Is a smooth welded TPO or PVC field | TPO- or PVC-coated drip edge, membrane heat-welded to the flange | Metal-Era One Drip Edge product data |
| Is EPDM | Edge metal stripped in with QuickSeam-type flashing, or a termination bar | Elevate RubberGard EPDM Design Guide |
| Is on a roof under 2:12 (any membrane) | An edge system tested to ES-1 RE-1, RE-2, RE-3 | IBC 2021 1504.6 |
| Needs a maker wind warranty over 80 mph | ES-1 certified metal and details; up to 90 mph with Elevate’s shop-fabricated ES-1 cleat program | Elevate design guide, Table 49 |
| Has a coping cap over 4 in wide on a parapet | A coping tested to ES-1 RE-3, not a drip edge | Professional Roofing, Oct 2018 |
| Is a shingle eave or rake, 2:12 or steeper | Shingle drip edge per IRC R905.2.8.5 | IRC 2021 R905.2.8.5 |
How the membrane and edge metal fit together, by system
Each flat roof system terminates its edge a specific way, and the maker’s detail sets the warranty. Elevate’s table of edge metal warranties shows the stakes: field-fabricated Elevate metal installed to NRCA or SMACNA details is covered up to 20 years at 55 mph, field-fabricated to Elevate’s own details up to 80 mph, and shop-fabricated ES-1 metal with a factory cleat up to 90 mph, while non-Elevate metal carries no edge warranty from Elevate.
EPDM (rubber)
On EPDM the membrane is carried over the nailer and either clamped with a termination bar or covered by edge metal whose flange is stripped in with cured flashing. In Elevate’s Platinum EPDM details, base tie-ins attach to substrates that resist at least 200 lbf in any direction, laps are primed and joined with 3 inch splice tape plus 5 inch QuickSeam flashing over sheet edges, and corners get a T-joint cover and 9 inch QuickSeam Corner Flashing.
TPO and PVC (welded single-ply)
TPO and PVC edges use coated metal, a drip edge with the same membrane laminated to its flange. The field sheet is hot-air welded directly to that coated flange, making a single welded plane from field to edge. Metal-Era backs its TPO- and PVC-coated One Drip Edge with a 10 year, 90 mph wind warranty when ordered to a project specification, and the product carries Miami-Dade approval for Florida’s High Velocity Hurricane Zone.
Built-up and modified bitumen
BUR and gravel roofs use a gravel stop with a raised leg to contain the aggregate. The metal flange is set in flashing cement, nailed on roughly 3-inch centers in a staggered pattern, and stripped in with two plies of felt or a membrane target sheet set in mastic. Modified bitumen edges torch or cold-adhere a cap sheet over the metal flange.
Does code require a flat roof drip edge?
Yes, low-slope roof edge metal is code-regulated, but under a different rule than shingle drip edge. IBC 2021 Section 1504.6 (Section 1504.5 in the 2018 edition) requires metal edge systems on built-up, modified bitumen, and single-ply roofs under 2:12, other than gutters and counterflashing, to be designed for Chapter 16 wind loads and tested to ANSI/SPRI ES-1 methods RE-1, RE-2, and RE-3. Per Carlisle SynTec’s ES-1 explainer (September 2022), RE-1 pulls on the membrane and the termination must hold at least 100 lb per foot, RE-2 is a pull-off test of the fascia, and RE-3 tests coping caps.
This matters because the roof edge is where wind uplift is highest. Professional Roofing (October 2018), NRCA’s magazine, cites RICOWI, FM Global, and SPRI studies after several early-2000s hurricanes that found nearly 60 percent of damage to roof systems was caused by failure at the perimeter. The residential shingle rule, IRC R905.2.8.5, requires drip edge at eaves and rakes of shingle roofs but does not govern membrane edge systems.
How to install a flat roof drip edge
Installing drip edge for a flat roof follows a fixed order: prep the edge, set the metal, then lap and seal the membrane over it. The sequence below is the general single-ply method. Always confirm fastener spacing and strip-in width against the membrane maker’s published edge detail and the edge system’s ANSI/SPRI ES-1 test listing.
- Prep the edge. Confirm the fascia or nailer is sound, dry, and at least nominal 2-inch lumber for fastener holding. Round or ease sharp edges so the membrane is not cut.
- Snap a line and dry-fit. Set the metal to a chalk line for a straight edge. Lap sections 3 to 4 inches in the direction of drainage and set the joints in sealant.
- Fasten the flange. Nail or screw the horizontal flange on roughly 4-inch centers, or per the ES-1 rated spacing, staggered. Use a continuous cleat on the fascia leg for high-wind edges.
- Lap the membrane over the top. Carry the field membrane over the metal flange. On TPO and PVC, weld the sheet to coated metal. On EPDM, strip in with 6-inch cover tape or wrap and clamp with a termination bar.
- Seal the terminations. Apply lap sealant or water block at cut edges, bar tops, and corners (Elevate uses 9 inch corner flashing on EPDM), using a product compatible with the membrane (see how to pick a flat roof sealant by membrane). Prefabricated corner pieces beat field-cut miters for watertightness.
- Check drainage. Confirm the field still falls at least 1/4 inch per foot (IRC R905.12.1 and R905.13.1) toward scuppers, drains, or gutters, and that the drip lip throws runoff clear of the fascia.
Materials, sizing, and gauge
Flat roof edge metal is specified by material, thickness, and face and flange dimensions. Heavier gauge and a longer roof flange raise wind resistance and help an edge pass ES-1; Metal-Era’s coated One Drip Edge, for example, is 24 gauge over a 22 gauge continuous cleat. For sheet metal it does not supply, Elevate’s 30-year Platinum details call for a Kynar-type finish, anodized aluminum, copper, or stainless steel.
| Material | Typical thickness | Notes |
|---|---|---|
| Aluminum | 0.032 to 0.050 in | Light, corrosion resistant, common on residential single-ply |
| Galvanized / Galvalume steel | 24 gauge | Strong, economical, standard for commercial gravel stop |
| Coated (TPO/PVC-clad) metal | 24 or 22 gauge core | Weldable flange for single-ply; buy to match the membrane brand |
| Copper | 16 oz | Premium, long life, used on visible or historic edges |
Face height usually runs 2 to 6 inches to cover the fascia and edge build, and the roof flange runs 3 to 5 inches for fastening and strip-in. Longer flanges and closer fastener spacing are what an ES-1 wind design calls for on tall or exposed buildings.
Cost of flat roof drip edge
Flat roof drip edge is priced by the piece, usually 10 or 12 ft lengths, plus the cleat, corners, and labor, so compare bids per linear foot of perimeter with those items listed. The biggest price steps are the metal and the wind rating: coated TPO or PVC metal must match the membrane brand, and Elevate’s warranty table ties wind coverage to fabrication, 55 mph for field-fabricated metal to NRCA or SMACNA details, 80 mph to Elevate details, and up to 90 mph for shop-fabricated ES-1 metal with a factory cleat.
On a retrofit, the bigger cost driver is what the edge ties into. Re-terminating existing membrane, replacing rotted fascia, and replacing nailers that cannot hold Elevate’s 200 lb per lineal foot minimum add labor that new construction does not have. Ask each bidder to list the edge profile, gauge, cleat, ES-1 test listing, and nailer work as separate lines.
For how the whole perimeter sheds water, see our guides on flat roof drainage design and the parapet wall flashing detail. For the membrane side of the edge, our EPDM roofing installation guide covers termination bars step by step, and you can compare systems in our breakdown of flat roof types. If you have a sloped or shingled roof instead, the rules differ, so read our separate guide to shingle roof drip edge. Start at the Learn About Roofing hub for the full library.
Frequently asked questions
Do flat roofs need a drip edge?
Yes. A flat or low-slope roof needs perimeter edge metal to shed water past the fascia and to anchor the membrane against wind uplift. Under IBC 2021 Section 1504.6, metal edges on membrane roofs under 2:12 must be tested to ANSI/SPRI ES-1. Professional Roofing cites post-hurricane studies that put nearly 60 percent of roof system damage at the perimeter.
What is the difference between a drip edge and a gravel stop?
Both are perimeter edge metal, but a gravel stop has a raised vertical leg that dams loose gravel or ballast so it cannot wash off a built-up or ballasted roof (ballasted roofs are limited to slopes under 2:12 by IBC 1507.12.3). A plain drip edge has a hemmed lower lip that sheds water but no raised leg, so it suits smooth EPDM, TPO, and PVC.
Does the membrane go over or under the drip edge on a flat roof?
Over. On a flat membrane roof the edge metal is fastened first, then the membrane laps over the top flange and is welded, taped, or clamped to it. That matches the shingle eave rule in IRC R905.2.8.5, where underlayment goes over the drip edge, and is the reverse of the rake, where underlayment goes under it.
What size drip edge do I need for a flat roof?
Face height usually runs 2 to 6 inches to cover the fascia and edge build, and the roof flange runs 3 to 5 inches for fastening. The flange must sit on a nailer at least 1/2 inch wider than the flange (Elevate). On tall or wind-exposed buildings, the ES-1 wind design may call for a longer flange, closer fastener spacing, and heavier gauge.
Is flat roof drip edge required by code?
Yes, low-slope roof edge metal is code-regulated. IBC 2021 Section 1504.6 (1504.5 in the 2018 IBC) requires metal edge systems other than gutters and counterflashing on roofs under 2:12 to be tested to ANSI/SPRI ES-1 methods RE-1, RE-2, and RE-3. The residential rule in IRC R905.2.8.5 covers shingle drip edge, not membrane edges.
Can you add a drip edge to an existing flat roof?
Often yes, but it means re-terminating the membrane at the perimeter. A roofer lifts or cuts back the edge membrane, sets new edge metal on a sound nailer, and strips or welds the membrane back over the flange. Rotted fascia or a nailer that cannot hold 200 lb per lineal foot (Elevate’s minimum) has to be replaced first, which drives the cost.