The junction where the flat roof covering meets the lantern kerb is a weak point on many extensions. Send photos from Chiswick (W4) and we'll tell you which it is — with the price agreed in writing before any work.

Signs you need flat roof junction and flashing repairs
- Leak near the lantern but not from the frame
- Missing or loose edge trims and flashings
- Ponding on the roof next to the lantern
Why it happens
Unbonded membrane
EPDM or single-ply that has come away from the kerb lets water run behind it.
Cracked GRP
Fibreglass roofs can crack at the kerb corner where movement concentrates.
Covering Chiswick and nearby
Drier, sunnier parts of the UK are kinder to seals than the wet west, but strong sun ages sealant, gaskets and plastic end caps, and south- or west-facing lanterns can make rooms very warm. Solar control glass and an opening vent help.
Across London, many lanterns sit on rear extensions with access only through the house, so we protect floors and plan the work to keep time indoors to a minimum. Parking and any permits are factored into the quote.
From Westminster to Chiswick is roughly 5 miles — all part of the Greater London area we cover.
Neighbouring places we cover include Acton (1 mile), Barnes (1 mile), Shepherds Bush (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?
Most lantern repairs in England need no approval at all. Where a job turns into a replacement, the Building Regulations 2010 apply and we confirm how the work will be signed off before we start. 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 Chiswick: questions
How do I get a price for flat roof junction and flashing repairs in Chiswick?
Send a few photos of the lantern and the problem, with your Chiswick postcode. We'll reply with a guide price and tell you whether a visit is needed before we can fix the price.
Do you need to visit to price flat roof junction and flashing repairs?
Not always. Clear photos are often enough for a guide price. Where the cause isn't obvious, a visit to inspect and water-test is charged from £145 ex VAT, confirmed before we come.
What does a junction repair cost?
Usually £245–£695 ex VAT, confirmed in writing before work starts.
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 Chiswick
- Roof lantern leak repairs in Chiswick
- Condensation diagnosis and fixes in Chiswick
- Timber roof lantern repairs in Chiswick
- Roof lantern respraying in Chiswick
- Leak investigation and inspection in Chiswick
- Cleaning and maintenance in Chiswick
Flat roof junction and flashing repairs near Chiswick
More about flat roof junction and flashing repairs · All roof lantern repairs in Chiswick