What it does
Where a flat roof meets a house wall, the membrane is turned up the brickwork to form an upstand. Its top edge is the weak point: wind can peel it back and rain running down the wall can get behind it. A termination bar is plugged and screwed into the wall along that edge, clamping the membrane flat against the masonry.
The bar is only a clamp. Sealant keeps the water out. Rubber4roofs, an EPDM supplier, puts water cut-off mastic behind the membrane and lap sealant along the angled slot at the top of the bar. Permaroof's 2020 catalogue says its bar must be used with water block seal and all-purpose fasteners (PDF p.16).
Where you will find it on a Yorkshire roof
Most often on the flat-roofed back extensions, kitchens and garages added to Victorian terraces and post-war semis, where the flat roof butts up to the house wall. Bars are also used on parapets and where a new EPDM roof joins older felt.
From an upstairs window it looks like a thin straight line of grey metal or black plastic along the wall, with screw heads and a bead of sealant on top. It should sit at least 150 mm above the roof surface, the minimum upstand IKO gives from BS 6229 and BS 8217.
On rubble stone walls in Pennine towns, the uneven face makes a straight bar hard to seal, so roofers often cut a chase into a mortar joint and fit a cover flashing instead.
Types and materials
| Type | What it is |
|---|---|
| Clamping bar with sealant slot | Aluminium, about 25 mm wide, in 3 m lengths, screwed through the membrane. The usual type on domestic EPDM roofs (Rubber4roofs, and Permaroof PDF p.16). |
| Lipped bar | Aluminium (1.6 mm) or black GRP (2.5 mm), 2.5 m long. Bauder fixes it above, not through, the finished upstand, with two sealant beads behind and sealant on the lip. |
| Trims | SIG Roofing lists GRP and aluminium termination bars with edge trims as an alternative to lead flashing (brochure, p.27). |
Into brick and concrete the bar can be fixed with nylon hammer-in anchors. SFS's Hammerfix takes a 6 mm hole with at least 30 mm embedment (SFS UK catalogue, pp.130 to 131). Fitting follows the membrane maker's instructions. BS 6229 is the code of practice for the roof as a whole, and its current edition took effect in December 2025.
How it fails and the signs
The sealant fails first. Sun and frost harden the bead along the top until it cracks and pulls away from the wall, and water runs down behind the membrane. Screws loosen as old masonry crumbles, and the bar bows away between fixings.
From the ground or a window, look for:
- gaps or missing lengths of sealant along the top edge
- a bar that has bowed or come away from the wall
- the membrane edge flapping or creased near the bar
- a damp patch on the ceiling nearest the house wall after wind-driven rain
A bar only seals the face of the wall. Rain soaking into porous brick above it can still run down inside the wall and out behind the upstand, which a chased flashing would shed. See damp patch on the ceiling and finding a roof leak.
Repair or replace
If the bar is sound, the job is small. The roofer cuts out the old sealant, replaces loose or rusted fixings and runs a fresh bead. If the membrane behind is torn, has shrunk down from the bar or the upstand is wet, the upstand is remade, often as part of re-covering the roof (see patch or replace a flat roof).
A bar is not always the best finish. Bauder restricts its bar to upstands where a chase cannot be cut, as the alternative to a lead counterflashing. Sika's standard single-ply details also show a counter flashing, a chase and a rendered finish. On brickwork with sound mortar joints, a chased lead or metal cover flashing is the usual choice. On render, cladding or concrete with no joint to cut, the bar is. If a re-cover adds insulation, the bar usually has to be refitted higher. More on flat roofing.
At a glance
- Part of
- The upstand detail where a flat roof meets a wall 1
- Materials
- Aluminium or GRP (glass-reinforced plastic) 1
- Fixing centres
- 300 mm on Bauder's bar; follow the membrane maker's figure 1
- Sealants
- Water cut-off mastic behind, lap sealant along the top 4
- Minimum upstand
- 150 mm above the roof surface 3
- Often used instead
- A lead or metal cover flashing in a chase 1
- Fixings into masonry
- Nylon hammer-in anchors, 6 mm hole, 30 mm minimum embedment (SFS Hammerfix) 7
Take a photo from the ground, a window or the loft and send it on WhatsApp. We will tell you what it is and whether it needs a visit. Quotes are free and itemised.
Sources
- Bauder, Termination Bar product page and technical data sheet (18 May 2026)
- Sika Ltd, Sika Single Ply Membrane Warm Roof Mechanically Fixed, selection of standard details (April 2024)
- IKO, Upstand requirements for flat roof design
- Rubber4roofs, Termination bar (help article)
- Bauder, BS 6229:2025 key changes and implications for flat roof design
- Permaroof UK, Roofing Catalogue 2020, PDF p.16 and p.17
- SFS UK, Flat Roofing 2026 UK Catalogue (05/2026 V1), pp.130 to 131
- SIG Roofing, Contractor Brochure (June 2020), p.27
General information about roofing in England, checked against the sources above when published. It is not a substitute for advice about your own roof.
