The junction where the flat roof covering meets the lantern kerb is a weak point on many extensions. Send photos from Derry~Londonderry (BT47) and we'll tell you which it is — with the price agreed in writing before any work.

Is it time for flat roof junction and flashing repairs?
- Leak near the lantern but not from the frame
- Splits, blisters or lifted edges in the roof covering by the kerb
- Missing or loose edge trims and flashings
Why it happens
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.
Covering Derry~Londonderry and nearby
Damp, mild winters keep moss and algae growing on flat roofs and lantern frames, which holds water against seals and blocks weep slots. Regular clearing makes a real difference in wetter areas.
Neighbouring places we cover include Strabane (14 miles), Limavady (15 miles), Portstewart (27 miles).
How much should it cost?
Most flat roof junction and flashing repairs jobs come in between £245 and £695 ex VAT (£294–£834 including 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 Northern Ireland?
Most lantern repairs in Northern Ireland need no approval at all. Where a job turns into a replacement, the Building Regulations (Northern Ireland) 2012 apply and we confirm how the work will be signed off before we start. 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.
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 Derry~Londonderry: questions
Do you cover Derry~Londonderry?
Yes. We cover Derry~Londonderry, including the BT47 postcode area, as part of County Londonderry. 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.
Which places near Derry~Londonderry do you cover?
As well as Derry~Londonderry, we cover nearby Strabane, Limavady, Portstewart, Coleraine and the rest of County Londonderry.
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 Derry~Londonderry
- Roof lantern leak repairs in Derry~Londonderry
- Roof lantern resealing in Derry~Londonderry
- Misted glass unit replacement in Derry~Londonderry
- Opening vent and actuator repairs in Derry~Londonderry
- Flat rooflight and skylight repairs in Derry~Londonderry
- Roof lantern replacement in Derry~Londonderry
Flat roof junction and flashing repairs near Derry~Londonderry
More about flat roof junction and flashing repairs · All roof lantern repairs in Derry~Londonderry