Roof Lantern Upstand and Kerb Repairs

The upstand, or kerb, is the raised frame the lantern sits on. It lifts the lantern clear of water on the flat roof and needs to be sound, level, insulated and properly covered by the roof membrane. Many 'lantern leaks' are actually kerb problems, and we repair or rebuild the kerb without replacing the lantern where possible.

Roofer dressing EPDM membrane up the timber kerb under a roof lantern

What are the signs you need upstand and kerb repairs?

Water appearing below the lantern rather than from the glass
Soft or spongy timber at the base of the lantern
Roof membrane not lapped up the kerb, or peeling off it
Ponding water against the kerb after rain
Cold, damp or mouldy lining around the opening

What usually causes it?

Kerb too low

If the kerb doesn't rise enough above the finished roof, water sits against the joint during heavy rain.

Membrane not dressed up

The flat roof covering should run up the kerb and be trimmed or flashed. If it stops short, water gets behind it.

Rotten timber

Untreated or wet timber kerbs rot from inside, so the lantern loses support and the seals open.

How do we fix it?

Survey the kerbWe check height, level, timber condition and how the roof covering is detailed.
Lift, repair or rebuildThe lantern is lifted where needed, rotten timber is replaced and the kerb is re-insulated and re-covered.
Refit and sealThe lantern is refitted and the junction sealed and trimmed to shed water.

Can a kerb be repaired without a new lantern?

Usually. Most lanterns can be lifted off, the kerb repaired or rebuilt, and the same lantern refitted with new seals. If the lantern is old or damaged it may be worth pairing the kerb repair with a replacement, but that's your call once you have both prices.

Does a kerb repair affect the flat roof?

The roof covering around the kerb has to be opened and re-made, so we price the junction into the same job and match the existing system (EPDM, GRP, felt or single-ply) as closely as possible.

What should you expect to pay for upstand and kerb repairs?

Guide price, per lantern£395–£1,295 ex VAT£474–£1,554 inc VAT · timber or insulated kerb repair and re-covering

Guide prices assume a standard lantern on a single-storey roof with safe ladder access. Where a tower or scaffold is needed we add it to the quote (typically £245–£895 ex VAT). Diagnostic visits start from £145 ex VAT. Your fixed price is confirmed in writing before any work starts. See all guide prices.

Where is this on the lantern?

Highlighted in amber: upstand or kerb.

Do you need permission for this work?

Straightforward repairs don't normally need building regulations approval or planning permission. Replacing a whole lantern, changing its size or working on a listed building is different, and the rules vary by nation:

England

In England, replacing a roof lantern or rooflight is generally treated like replacing a window: the work must meet the Building Regulations (energy efficiency under Approved Document L, and safety glazing), and it's either done by an installer registered with a competent person scheme or notified to building control with an application. Enlarging the opening always needs a building regulations application. Replacing only the sealed glass units in an existing frame is usually treated as a repair rather than notifiable work, but the new glass should be no worse than before — if you're unsure, check with building control. We confirm in writing which route applies before any replacement.

Listed buildings need listed building consent from the local council for alterations, and conservation areas can have extra controls; like-for-like repairs are treated differently from changes, so check with the council's conservation officer first.

Wales

In Wales, building regulations are devolved and the Welsh Government publishes its own Approved Documents. Installing a new rooflight generally needs approval; for a replacement, the Welsh Government suggests using an installer registered with the relevant competent person scheme, or otherwise involving building control, and the new lantern must meet the Welsh energy-efficiency requirements. We confirm in writing which route applies before any replacement.

Listed buildings in Wales need listed building consent from the local planning authority for alterations, with Cadw guidance on historic buildings; check with the council before changing a lantern on a listed property.

Scotland

In Scotland, the Building (Scotland) Regulations 2004 and the Technical Handbooks apply. Under schedule 3, replacing a rooflight including its frame doesn't need a building warrant but must meet the building standards in full; other work to a rooflight, including reglazing, must leave it no worse than before. New or enlarged openings are different and normally need a warrant. We confirm in writing which applies before any replacement.

Listed buildings in Scotland need listed building consent from the planning authority for alterations, with Historic Environment Scotland guidance; check before changing a lantern on a listed property.

Northern Ireland

In Northern Ireland, the Building Regulations (Northern Ireland) 2012 and the Technical Booklets apply, administered by your council's Building Control service. Replacement glazing, including rooflights, must meet the energy-efficiency requirements, and an application may be needed depending on the work. We check with Building Control and confirm in writing which route applies before any replacement.

Listed buildings in Northern Ireland need listed building consent from the council for alterations; check with the council's planning service before changing a lantern on a listed property.

Questions about upstand and kerb repairs

How much does an upstand repair cost?

Typically £395–£1,295 ex VAT depending on size, timber condition and the roof covering. The fixed price is confirmed in writing before work starts.

Can you add insulation to the kerb?

Yes. Insulated kerbs reduce cold bridging and help with condensation around the opening.

Will my ceiling need repairing?

If water has soaked the lining it may need making good after the leak is fixed; we can advise, but internal decorating isn't included unless quoted.

Where do we carry out upstand and kerb repairs?

We cover the whole of the UK. Choose your area for local details and towns we cover.

Roof lantern upstand and kerb repairs