The junction where the flat roof covering meets the lantern kerb is a weak point on many extensions. Send photos from Croydon (CR0) and we'll tell you which it is — with the price agreed in writing before any work.

What you might be seeing
- Leak near the lantern but not from the frame
- Missing or loose edge trims and flashings
- Ponding on the roof next to the lantern
Common causes we find
Unbonded membrane
EPDM or single-ply that has come away from the kerb lets water run behind it.
Missing trims
Without a trim or flashing to protect the top edge, water gets in behind the membrane.
Covering Croydon and nearby
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.
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 Croydon is roughly 8 miles — all part of the Greater London area we cover.
If you're just outside Croydon, we also cover South Croydon (1 mile), Wallington (3 miles), Carshalton (3 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?
In England, like-for-like repairs to a roof lantern don't usually involve building control. A full replacement or a bigger opening is controlled under the Building Regulations 2010, so we set out the route in writing first. 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 Croydon: questions
Do you cover Croydon?
Yes. We cover Croydon, including the CR0 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 Croydon?
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.
What does a junction repair cost?
Usually £245–£695 ex VAT, confirmed in writing before work starts.
Other lantern repairs in Croydon
- Roof lantern resealing in Croydon
- Misted glass unit replacement in Croydon
- Cracked lantern glass replacement in Croydon
- Solar control and self-cleaning glass upgrades in Croydon
- Condensation diagnosis and fixes in Croydon
- Cleaning and maintenance in Croydon
Flat roof junction and flashing repairs near Croydon
More about flat roof junction and flashing repairs · All roof lantern repairs in Croydon