What it is for
When a flat roof covering is turned up a wall to make an upstand, the cut edge at the top is its weakest point. Wind can work underneath it, and water coming down the brickwork can slip in behind. The bar is one continuous clamp along that edge, fixed into the wall at intervals so the membrane is pressed hard against it.
The bar holds and the mastic seals. Rubber4roofs, an EPDM supplier, has water cut-off mastic compressed behind the membrane by the bar, with lap sealant run into the angled slot on top. Permaroof's 2020 catalogue makes water block seal and its all-purpose fasteners a condition of using its bar (p.16).
Where you will see one around Barnsley
The usual spot is where a flat-roofed kitchen, bathroom or garage joins the brick wall of the house behind it. Bars are also used inside parapets, and Rubber4roofs lists tying a new EPDM roof into existing felt among the bar's uses.
From a bedroom window it shows as a narrow straight strip, grey aluminium or black plastic, with screw heads at intervals and a line of sealant above. IKO, citing BS 6229 and BS 8217, gives 150 mm as the minimum upstand, so the bar normally sits at least that high above the roof.
Conservation areas can call for a different finish. In Elsecar, Barnsley Council's best practice guidance says lead flashing on historic properties should be replaced with lead, Flashband should not be used, and defective pointing should be raked out by hand and repointed in lime mortar. On a historic wall there, lead is normally renewed like for like rather than swapped for a bar.
Types and materials
- Slotted clamping bar. Aluminium, about 25 mm wide, sold in 3 m lengths and screwed to the wall over the membrane, with a groove on top for sealant. The common choice on house EPDM roofs (Rubber4roofs, and Permaroof p.16).
- Deep profile bar. Bauder makes one in black GRP or aluminium, 2,500 mm long and 82 mm deep, offered in place of lead counterflashing at upstands.
- Bars with trims. SIG Roofing's contractor brochure lists bars in GRP or aluminium alongside edge trims, the parts that hold membranes at their edges (June 2020, p.27).
In concrete, solid brick and masonry the bar is often held with hammer-in nylon anchors. SFS lists its Hammerfix anchor for this, set 30 mm deep or more in a 6 mm drilled hole (Flat Roofing 2026 catalogue, pp.130 to 131). Fixing centres and sealant type come from the membrane maker. The roof as a whole falls under BS 6229, the flat roof code of practice, published in its 2025 edition by BSI on 16 December 2025.
How it fails and the signs
Sealant usually goes first. Years of sun and frost stiffen the bead on top until it shrinks, cracks and parts from the wall, and rain then trickles in behind the membrane. In soft or crumbling masonry the fixings work loose and the bar bows out between them.
From a window or the garden, check for:
- sealant missing, split or standing away from the wall
- a bar bent outwards or hanging loose at one end
- membrane creased, flapping or slipping down beneath the bar
- a ceiling stain close to the house wall after driving rain
A bar only handles water on the outside surface. Rain absorbed by porous brick higher up can travel down inside it and come out behind the upstand, where a flashing set into a joint would have turned it outwards.
Repair or replace
Where the bar itself is sound, the roofer cuts away the old sealant, swaps loose or corroded fixings and runs a new bead. A torn or shrunken membrane, or a wet upstand, means remaking the upstand, often while re-covering the flat roof or, on EPDM and PVC, the single ply system.
Bars and flashings each have their place. Bauder says its own bar belongs only on upstands where no chase can be cut into the wall. Brickwork with sound joints usually gets a lead cover flashing dressed into a chase. A rendered, clad or concrete wall offers no joint to open up, so there the bar makes sense. If added insulation raises the roof, the bar has to move up with it.
At a glance
- Part of
- The wall abutment, finishing the upstand 1
- Made from
- Aluminium, or black GRP (glass-reinforced plastic) 1
- Typical sizes
- Rubber4roofs: 25 mm by 3 m. Bauder: 2,500 mm long, 82 mm deep 3
- Seals used
- Water cut-off mastic under the membrane, lap sealant along the top groove 3
- Upstand it finishes
- At least 150 mm high, per IKO 2
- Into masonry
- SFS Hammerfix nylon anchors, set 30 mm or more into a 6 mm hole 7
- Preferred where a chase can be cut
- Lead counterflashing (Bauder) 1
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
- IKO, Upstand requirements for flat roof design (9 Jan 2022)
- Rubber4roofs, Termination bar (help article)
- BSI, BS 6229:2025 Flat roofs with continuously supported flexible waterproof coverings. Code of practice (published 16 Dec 2025)
- Barnsley Council, Supplementary Planning Document: Elsecar Conservation Area Best Practice, Design and Maintenance (adopted 2019), paras 10.1.5 and 10.1.6
- Permaroof UK, Roofing Catalogue 2020, PDF p.16
- SFS UK, Flat Roofing 2026 UK Catalogue, 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.
