What an upstand does
Where a flat roof meets something upright, the waterproofing is carried up its face, so rain, splash and shallow standing water meet membrane instead of an open joint. The top edge is clamped and covered, so water running down the wall passes over it.
Bauder's summary of BS 6229:2018 gives 150 mm above the finished roof level at every abutment and penetration; IKO notes the height also deals with rain splashing up off the surface. BSI published a revised edition, BS 6229:2025, in December 2025. Bauder's summary of its changes lists no change to upstand height.
Where you will find it on a Yorkshire roof
The commonest place is a back extension or garage roof against the rear wall of a Victorian terrace or post-war semi. The covering turns up the brickwork and finishes under a lead or trim flashing set into a mortar joint, often visible from an upstairs back window.
You will also find upstands round the raised kerbs that carry rooflights and roof lanterns, around soil and vent pipes, at chimney stacks, and inside parapet walls above shops and flats. Indoors, a fault at an upstand usually shows as a damp patch on the ceiling near the wall.
Types and materials
| Type | Where | How the top is finished |
|---|---|---|
| Wall abutment | Extension or garage roof against the house wall | Termination bar screwed through the membrane on a sealant bed, or a flashing trim set into a raked out mortar joint (Permaroof) |
| Parapet | Inside face of a low wall round the roof | Taken up under the coping or held with a termination bar fixed into the masonry (SFS) |
| Rooflight kerb | Timber or plastic kerb under a rooflight | Turned up the kerb and finished under the rooflight frame |
| Pipe collar | Soil and vent pipes | Preformed boot or collar clamped to the pipe |
| Door threshold | Door onto a balcony or roof terrace | May drop to 75 mm under an overhanging sill, only with falls away from the door and proper drainage (Bauder) |
| Check kerb | Open roof edge | A lower kerb, at least 50 mm and usually 75 mm, according to IKO |
The upstand uses the roof's own system: felt, EPDM rubber, single ply PVC, liquid coating or mastic asphalt. On EPDM, Permaroof specifies contact adhesive on brick upstands. An angle fillet at the base lets the membrane turn the corner without a sharp 90 degree fold. Under the NFRC's Safe2Torch guidance, as Sika sets it out, timber upstands, fillets and rooflight kerbs are torch free areas, and a self adhesive membrane is used within 900 mm of the nearest combustible material.
How it fails and the signs
Most upstand leaks start at the top edge: sealant above a termination bar cracks, or a flashing or its pointing works loose, and rain runs in behind the membrane. Membranes can also shrink or lose adhesion and pull away from the corner, and old asphalt skirtings sag and crack along the top.
Height is the other fault. Overlaying a roof with thicker insulation raises the surface and can leave an upstand too low. Sika's refurbishment brochure describes raising the perimeter details to suit new insulation. Water that pools against the wall after rain makes a low upstand worse.
From a window you may see a loose flashing, a gap along the top of the covering, moss in the corner, or dark staining on the brick just above the roof. Inside, look for stained plaster where ceiling meets wall. Left alone, water reaches the insulation and the timber deck.
Repair or replace
A roofer first finds where water gets in, which can be above the upstand through porous brick. Small jobs include resealing or refitting a termination bar, refixing and repointing a flashing, and patching a split corner with a compatible material.
It becomes a bigger job when the edge deck is soft, the insulation is wet, or the upstand is too low to reach 150 mm without rebuilding. It is then remade as part of a patch or full replacement of the flat roof. Where the upstand meets lead, the cover flashing is often renewed too.
At a glance
- Governing standard
- BS 6229:2025, flat roofs with continuously supported flexible waterproof coverings 1
- Minimum height
- 150 mm above the finished roof level (BS 6229:2018, as summarised by Bauder) 2
- Measured from
- The membrane on an exposed roof; the finished surface, including anything laid over the waterproofing, on other roofs 3
- Door thresholds
- 75 mm under an overhanging sill, only with falls away and drainage 2
- Top finished with
- Termination bar on water block sealant, or a wall flashing trim 6
- Torch free zone
- Timber upstands and rooflight kerbs; self adhesive within 900 mm of combustibles 5
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
- BSI, BS 6229:2025 Flat roofs with continuously supported flexible waterproof coverings. Code of practice (published 16 Dec 2025)
- Bauder, Changes to BS 6229:2018
- IKO, Upstand requirements for flat roof design (9 Jan 2022)
- Bauder, BS 6229:2025 The key changes and implications for flat roof design (May 2026)
- Sika Ireland, Safe2Torch and Sika bitumen membranes
- Permaroof UK, Roofing Catalogue 2020, PDF p.5, 6, 12, 16
- SFS UK, Flat Roofing 2026 UK Catalogue, p.130
- Sika, Hospitals and Healthcare Buildings roof refurbishment brochure (Aug 2021), p.6
General information about roofing in England, checked against the sources above when published. It is not a substitute for advice about your own roof.
