What it is for
Any corner between a flat roof and something upright collects water. Instead of leaving an open joint there, the roofer takes the same membrane, felt or asphalt up the vertical face, so water lying on the roof or bouncing off it meets unbroken waterproofing. The top of the turn-up is fixed and covered so rain coming down the wall is shed over it.
The figure most often quoted is 150 mm. Bauder's guide to BS 6229:2018 applies it at all abutments and penetrations, and IKO points out that heavy rain can splash higher than the roof surface. BSI issued BS 6229:2025 on 16 December 2025 to replace the 2018 edition. Bauder's May 2026 review of what changed does not mention upstand height.
Where you will see one on a Barnsley house
Most flat roofs on houses in the borough sit over a back kitchen, bathroom extension or garage built against the main wall. There the covering is turned up the brickwork and capped either by a flashing tucked into a mortar joint or by a metal or plastic bar. From a back bedroom window it is often in plain view.
Other upstands run round the kerb under a rooflight or roof lantern, round soil pipes and vents, at the foot of a chimney, and inside parapet walls. In Elsecar, Barnsley Council's best practice document says lead flashing on historic properties should be replaced with lead and that Flashband is not appropriate.
Types and materials
- Wall abutment. The roof meets the house wall. The top is held by a termination bar bedded on water block sealant or covered by a wall flashing trim; Permaroof's 2020 catalogue shows both (pp.12, 16).
- Parapet. The covering rises up the inside of a low perimeter wall and finishes under the coping or a fixed bar.
- Kerb. A raised frame under a rooflight or hatch, with the covering dressed up each side.
- Level threshold. At a door onto a balcony, Bauder accepts 75 mm under a sill that overhangs by at least 45 mm, if the roof falls away from the door and an outlet and overflow pipe are fitted.
- Check kerb. A low kerb along an open edge. IKO gives at least 50 mm, with 75 mm as good practice.
Each upstand is formed in the roof's own material, whether felt, EPDM, PVC, liquid coating or asphalt. An angle fillet in the corner lets the sheet turn gradually rather than fold at a right angle. Under the NFRC's Safe2Torch campaign, as Sika explains it, timber upstands, timber fillets and rooflight kerbs are not to be torched, and self adhesive membrane is used within 900 mm of anything combustible.
How it fails and the signs
In most cases the top edge goes first. Sealant along a bar dries and opens up, or a flashing works out of its joint as the pointing crumbles, and water gets in behind the covering. Felt and rubber can also come unstuck or shrink back from the corner, and old asphalt skirtings slump and split.
The other fault is an upstand that has become too short. Overlaying a roof with new insulation lifts its surface, so the edges must rise too; a Sika refurbishment brochure describes perimeter details raised for that reason (2021, p.6).
From a window or the garden, look for:
- a flashing that has lifted, bent or pulled out of its joint;
- a dark gap or split along the top edge of the covering;
- damp-looking brick just above the roof line.
Indoors, watch for a stain where ceiling meets wall after rain. A leak left running soaks the insulation and rots the deck boards along that edge.
Repair or replace
The roofer first traces where the water enters, since damp beside an upstand can come from higher up the wall. Resealing a bar, refixing and repointing a flashing, or patching a split corner in a compatible material are all small jobs.
It becomes a larger job when the edge decking has gone soft, water has reached the insulation, or 150 mm cannot be reached without rebuilding. The upstand is then formed again when the flat roof is re-covered, and the lead cover flashing above it is usually renewed at the same visit. Shop and industrial units are covered under commercial roof repairs and maintenance.
At a glance
- Governing standard
- BS 6229:2025, the British code of practice for flat roofs (published December 2025) 1
- Minimum height
- 150 mm, at every abutment and penetration (Bauder's reading of BS 6229:2018) 2
- Measured from
- Membrane surface on a bare roof (IKO); top of any paving, gravel or planting laid over it (Bauder) 3
- Level door threshold
- 75 mm beneath a sill overhanging 45 mm or more, with conditions 2
- Check kerb
- At least 50 mm, 75 mm as good practice 3
- No-torch areas
- Timber upstands and fillets, rooflight kerbs; within 900 mm use self adhesive 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
- Barnsley Council, Supplementary Planning Document: Elsecar Conservation Area Best Practice, Design and Maintenance (adopted 2019), para 10.1.6
- Permaroof UK, Roofing Catalogue 2020, PDF pp.12 and 16
- 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.
