In Chepstow, 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.

Is it time for 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
What usually causes it?
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.
Roof lanterns in Chepstow
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.
We cover Chepstow as part of Gwent, about 14 miles from Newport, Gwent.
If you're just outside Chepstow, we also cover Monmouth (12 miles), Newport, Gwent (14 miles), Cwmbran (15 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 Wales?
Straightforward repairs — resealing, gaskets, cappings, eaves and like-for-like parts — don't normally need building regulations approval in Wales. Replacing the whole lantern or enlarging the opening is different and falls under the Building Regulations 2010 (as applied in Wales); we confirm in writing which route applies before any replacement. Listed buildings in Wales need listed building consent from the local planning authority for alterations, with Cadw guidance on historic buildings; check with the council 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 Chepstow: questions
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.
Which places near Chepstow do you cover?
As well as Chepstow, we cover nearby Monmouth, Newport, Gwent, Cwmbran, Pontypool and the rest of Gwent.
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 Chepstow
- Upstand and kerb repairs in Chepstow
- Cracked lantern glass replacement in Chepstow
- Opening vent and actuator repairs in Chepstow
- Flat rooflight and skylight repairs in Chepstow
- Cleaning and maintenance in Chepstow
- Orangery lantern repairs in Chepstow
Flat roof junction and flashing repairs near Chepstow
More about flat roof junction and flashing repairs · All roof lantern repairs in Chepstow