Termination Bar: What It Is and How to Install It

A termination bar is a flat strip of metal or plastic, pre-punched with holes, that clamps the top edge of a roofing or waterproofing membrane to a wall or curb. Roofers call it a "term bar." It holds the membrane tight so wind can't peel it back and water can't get behind the edge, and it's sealed along the top. On most roofs it's then covered by a counterflashing, so you rarely see it on a finished job.

Where termination bars are used

• Low-slope roofs: at the top of the membrane where EPDM, TPO, PVC or modified bitumen turns up a parapet, wall, curb or penthouse.
• Box gutters: where a membrane lining is carried up the back wall of a box gutter.
• Below-grade waterproofing: at the top edge of a foundation membrane.
• Decks and balconies: where a waterproofing membrane meets a wall.

Sizes and materials

The most common bar is aluminum, about 1 inch wide and 1/8 inch thick, sold in 10-foot lengths with holes every 6 or 8 inches. Many have a lip at the top edge that holds a bead of sealant. Plastic and stainless versions exist for special conditions, and stainless or coated bars are used where aluminum would touch fresh concrete.

Installation steps

1. Prepare the wall. It must be smooth, clean and sound. Fill voids in block and grind high spots, or the bar won't seal.
2. Run the membrane up the wall to the height the roofing manufacturer specifies (often 8 inches above the roof surface or more) and adhere it.
3. Set the bar level, a little below the top edge of the membrane, so some membrane sticks out above it.
4. Fasten through every pre-punched hole with fasteners made for the substrate (masonry anchors in block or concrete, screws in wood). Typical spacing is every 6 to 8 inches, but follow the membrane maker's detail. Don't skip holes.
5. Seal the top edge with a sealant compatible with the membrane, tooled so it sheds water.
6. Counterflash with metal set in a reglet, a surface-mounted counterflashing, or the wall cladding lapping over it, unless the system's details allow an exposed bar.

Exposed or covered?

Some manufacturers allow an exposed termination bar on short curbs or where the wall above is not water-permeable, as long as the sealant is maintained. On masonry walls, though, water passes through the brick and mortar above the bar and runs down behind the membrane. That's why most details put counterflashing over the bar, or bring the membrane all the way over the wall top under a metal coping.

Common mistakes

• Bar installed over a rough wall, leaving gaps between fasteners
• Fasteners spaced too far apart or skipped holes
• Sealant not compatible with the membrane, or never applied
• Bar set too high, with no membrane above it to seal against
• Relying on an exposed bar on a brick wall with no counterflashing

When a flat roof leaks along a wall, the term bar and the sealant above it are among the first things to check.