In Blackheath, as everywhere, the junction where the flat roof covering meets the lantern kerb is a weak point on many extensions. Send photos and we'll tell you what we think has failed.

Signs you need flat roof junction and flashing repairs
- Splits, blisters or lifted edges in the roof covering by the kerb
- Missing or loose edge trims and flashings
- Ponding on the roof next to the lantern
Common causes we find
Cracked GRP
Fibreglass roofs can crack at the kerb corner where movement concentrates.
Missing trims
Without a trim or flashing to protect the top edge, water gets in behind the membrane.
About Blackheath and the SE3 area
Sun and UV do more damage than rain on many lanterns here: brittle ridge caps, chalky finishes and hardened gaskets. They're cheap to replace before they let water in.
London's extensions are often tight to neighbouring walls and roofs. Where a repair needs access over a neighbour's property, we'll tell you in advance so you can arrange it.
Blackheath is around 7 miles from Westminster, and both are within our Greater London coverage.
Close by, we also cover Greenwich (1 mile), Catford (2 miles), Eltham (2 miles).
How much should it cost?
Guide price for flat roof junction and flashing repairs: £245–£695 ex VAT (£294–£834 inc VAT), per lantern. Towers or scaffold, where needed, are priced into the quote. Your fixed price is confirmed in writing before any work starts.
Do you need permission in England?
Straightforward repairs — resealing, gaskets, cappings, eaves and like-for-like parts — don't normally need building regulations approval in England. Replacing the whole lantern or enlarging the opening is different and falls under the Building Regulations 2010; 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.
How does it work?
- Send photosWhatsApp or upload a few photos and tell us when it leaks.
- Guide priceWe reply with a guide price and whether a visit is needed.
- Fixed price in writingYou approve the price and the date before anything starts.
- Repair and testWe fix what's failed, water-test where it matters, and send photos.
Flat roof junction and flashing repairs in Blackheath: questions
Do you cover Blackheath?
Yes. We cover Blackheath, including the SE3 postcode area, as part of Greater London. Send photos by WhatsApp or the form for a free guide price, and we'll confirm the fixed price in writing before any work starts.
Can you repair a lantern someone else installed in Blackheath?
Yes. We repair lanterns whoever fitted them. If yours is still under the installer's warranty, contact them first so you don't affect it.
Do you repair the whole flat roof?
We repair the area around the lantern. If the wider roof is failing we'll tell you and can quote, but we won't push a new roof if a local repair will do.
Can you repair a GRP roof without it showing?
Repairs are colour-matched as closely as possible, but new topcoat next to weathered topcoat can look slightly different at first.
Other lantern repairs in Blackheath
- Misted glass unit replacement in Blackheath
- Condensation diagnosis and fixes in Blackheath
- Timber roof lantern repairs in Blackheath
- Leak investigation and inspection in Blackheath
- Cleaning and maintenance in Blackheath
- Roof lantern replacement in Blackheath
Flat roof junction and flashing repairs near Blackheath
More about flat roof junction and flashing repairs · All roof lantern repairs in Blackheath