In Lisburn, 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.

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
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.
Roof lanterns in Lisburn
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.
Near the coast, salt in the air is hard on aluminium finishes and fixings; washing the frame occasionally and touching in chips keeps corrosion away.
Lisburn is around 7 miles from Belfast, and both are within our County Antrim coverage.
Close by, we also cover Belfast (7 miles), Newtownabbey (11 miles), Holywood (12 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 Northern Ireland?
Straightforward repairs — resealing, gaskets, cappings, eaves and like-for-like parts — don't normally need building regulations approval in Northern Ireland. Replacing the whole lantern or enlarging the opening is different and falls under the Building Regulations (Northern Ireland) 2012; we 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.
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 Lisburn: questions
How do I get a price for flat roof junction and flashing repairs in Lisburn?
Send a few photos of the lantern and the problem, with your Lisburn 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.
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 Lisburn
- Roof lantern leak repairs in Lisburn
- Eaves beam and gutter repairs in Lisburn
- Misted glass unit replacement in Lisburn
- Aluminium roof lantern repairs in Lisburn
- Roof lantern respraying in Lisburn
- Roof lantern replacement in Lisburn
Flat roof junction and flashing repairs near Lisburn
More about flat roof junction and flashing repairs · All roof lantern repairs in Lisburn