How to Terminate EPDM at Roof Edges and Walls: Drip Edge, Bars and Counter Flashing
The edge is where wind gets under a roof and water gets behind it. Metal, bar, sealant and a covered top, in that order.
- Advanced
- 1 to 3 hours per 50 feet of edge
- Updated
The short answer
Terminate EPDM at a wall with a termination bar fastened through the membrane every 6 to 12 inches, a bead of sealant along the top edge, and counter flashing, siding or coping over it. At a roof edge, adhere the membrane to a drip edge or gravel stop flange with splice tape and cover strip. Keep the perimeter well secured, because wind uplift starts at edges.
Perimeter details decide whether a roof survives a storm. Wind lifts a membrane from its edges first, and once air gets under the edge the whole roof can peel back. Water also finds the edges, running behind a wall termination or over an unprotected edge onto the fascia. So terminations and edges have two jobs: hold the membrane down against uplift and keep water out of the top edge and the structure.
There are two main types of edge. At a wall, the membrane runs up the vertical surface and is held at the top with a termination bar and covered by counter flashing or cladding. At an open roof edge, the membrane runs to a metal drip edge or gravel stop, where it is tied to the metal and the metal is tied to the building. Each detail has a standard method and a set of details that get missed.
Edges follow the field in how to install a fully adhered EPDM roof and the corners in how to flash inside and outside corners on EPDM. For the metal itself, see how to install drip edge and parapet coping.
Tools
- Drill or impact driver
- Caulking gun
- Hand roller
- Tin snips for metal
- Utility knife
- Chalk line and level
- Tape measure
Materials
- Aluminum or stainless termination bar
- Drip edge or gravel stop metal
- Stainless or corrosion-resistant fasteners
- Splice tape and primer
- Lap sealant and termination sealant
- Uncured flashing or cover strip
- Counter flashing or coping metal
Safety first
- Edges are where falls happen. WorkSafeBC requires fall protection at 3 metres (about 10 feet) and wherever a fall of any height could cause serious injury. Set guardrails or anchors before working the perimeter.
- Metal edges are sharp. Wear cut-resistant gloves when cutting, bending or handling drip edge and bars.
- Drilling into walls can hit wires or pipes. Check what is behind the wall before fastening.
- Sealants and primers are flammable. Ventilate and keep flames away.
Step by Step
Step 1: Adhere the membrane up the wall to the right height
The membrane is adhered up the wall to at least 8 inches above the roof surface or the manufacturer's minimum, and higher where water or snow can pond. Leave the top few inches for the bar, and keep it flat, with no wrinkles or bridging at the corner between roof and wall.
Check that the wall is sound, flat and free of dust. Masonry is primed if the adhesive requires.
Step 2: Fasten the termination bar
A termination bar is a metal strip with a flange, commonly aluminum or stainless, fastened through the top edge of the membrane to hold it against the wall. Fastener spacing is typically 6 to 12 inches on centre, depending on the product and wind exposure, and the bar needs solid backing such as masonry, concrete or blocking, not just thin cladding.
Keep fasteners snug but not crushing. Lap bar ends by about 1/4 to 1/2 inch, or leave a small gap for expansion as the bar manufacturer directs.
Step 3: Seal the top edge
Apply a sealant compatible with EPDM and the wall along the top edge of the bar and membrane, pressing it in so there is no gap. Tool it to a slope so water runs off rather than collecting. Seal every fastener head as the manufacturer specifies.
This sealant is a secondary defence. The primary protection is whatever covers the bar: counter flashing, siding or coping.
Step 4: Cover the bar with counter flashing, cladding or coping
A counter flashing is a metal strip set into a reglet or fastened to the wall that laps down over the membrane and bar. Siding and stucco can also cover the termination if they lap over it with clearance. At parapets, coping caps the whole wall and sheds water onto the roof. See how to install counter flashing and how to cut a reglet.
Do not leave the top of a wall flashing relying on sealant alone. It cracks within a few seasons.
Step 5: Install the drip edge or gravel stop at open edges
At an eave or open edge, a metal drip edge or gravel stop is fastened to the deck and fascia, with its flange lying on the deck. The fastener spacing is commonly about 3 to 6 inches on centre at the flange, with laps between pieces of about 4 inches sealed with a bed of sealant, and the flange is primed if needed. See how to install drip edge.
Choose a metal compatible with EPDM and with neighbouring metals to avoid galvanic corrosion.
Step 6: Adhere the membrane to the metal and cover the joint
The membrane is adhered over the flange of the drip edge or gravel stop, and a strip of EPDM or flashing is taped over the joint, extending at least 3 inches onto the membrane and onto the metal. Metal surfaces need cleaning and priming with the product the manufacturer names.
Stripping-in the joint covers the gap where the membrane meets the metal and gives a flat path for water to run onto the membrane and off the edge.
Step 7: Check the perimeter for wind uplift
Wind uplift is greatest at edges and corners. Make sure the membrane is fully adhered to the edge, with no loose areas, and that bars and metal are fastened at the closer spacings. On exposed sites, some manufacturers call for extra fasteners or wider bars at perimeters and corners.
Consider the local wind. Outflow winds from the Fraser Canyon and storms off the river can be strong, so perimeter work is not the place to economize.
Edge Metals and Compatibility
- Aluminum or stainless bars: corrosion resistant, the usual choice.
- Galvanized or painted steel drip edge: common, but keep cut edges coated.
- Dissimilar metals: avoid contact between metals that cause galvanic corrosion, such as copper and aluminum.
- Sealants: use products approved for EPDM, not general purpose or asphalt-based products.
Fraser Valley Notes
Edges in the valley face sideways rain, moss and wind. Tops of walls that are open to the weather should be covered by counter flashing or coping, and sealant joints get checked each autumn. Drip edges need to be kept clear of needles and debris so water runs off rather than behind.
Common Mistakes
- Termination bar into thin cladding. It pulls out. Fasten into solid backing.
- Sealant as the only protection. It cracks, and water gets behind the membrane.
- Short flashing height. Under 6 inches leaks when water ponds or snow melts against the wall.
- Loose membrane at the perimeter. Wind lifts it first at edges and corners.
- Wrong metal. Galvanic corrosion eats fasteners and edge metal.
- No cover strip at the drip edge. The joint between membrane and metal opens and leaks.
When to Call a Professional
Edges and terminations combine waterproofing, metal work and wind resistance. If the wall is masonry, stucco or a parapet, if the building is tall or exposed, or if you need counter flashing set into a reglet, call a roofer. A failed edge can lose a whole roof in one storm.
If you are dealing with a lifted or open edge on an existing roof, see how to repair an EPDM roof.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Flat Roofing and Torch On service or the towns we cover.
How to Terminate EPDM at Edges and Walls: Questions
What is a termination bar on EPDM?
A termination bar is a strip of aluminum or stainless metal with a flange, fastened through the top edge of the membrane at a wall to hold it tight against the surface. It is fastened every 6 to 12 inches, sealed along the top edge and covered by counter flashing, siding or coping. It stops the membrane peeling and water running behind.
How do you finish EPDM at a roof edge?
Fasten a metal drip edge or gravel stop to the deck, adhere the membrane over its flange with primer and splice tape, and cover the joint with a strip of EPDM or flashing that laps at least 3 inches onto both the membrane and the metal. The metal is fastened at close spacing to resist wind uplift.
How high should EPDM go up a wall?
Commonly at least 8 inches above the finished roof surface, with the top terminated by a bar and covered by counter flashing, cladding or coping. Higher is better where water or snow can build up against the wall. Follow the membrane manufacturer's detail and the building code for your location.
Why do EPDM roofs blow off at the edges?
Wind forces are highest at perimeters and corners, so any loose membrane or weak fastening there lifts first, and once air gets under the edge it can peel the sheet back. Causes include incomplete adhesion at the edge, widely spaced fasteners, a missing termination bar or a drip edge that was not well fastened.
Related Guides
All EPDM Rubber Roofing guides|The full How-To Library
This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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