Resealing is the planned, whole-lantern version of a leak repair: we cut out the old, failed sealant, clean every joint back to a sound surface and reseal the cappings, ridge and eaves with materials that suit the frame. Send photos from Caerphilly (CF83) and we'll tell you which it is — with the price agreed in writing before any work.

Signs you need roof lantern resealing
- Cracked, split or shrunken sealant along the bars
- Black mould or dirt lines trapped in old silicone
- A lantern that is 8–15 years old and has never been maintained
What usually causes it?
Sealant past its life
Exposed sealant on a roof takes UV, frost and constant expansion and contraction. It hardens, loses grip and pulls away from the glass.
Patch over patch
Fresh sealant run over old, dirty sealant rarely bonds. It looks fixed for a season and then lets go.
Roof lanterns in Caerphilly
Wind-driven rain is the real test of a roof lantern, and the wetter west sees plenty of it. Leaks that appear only in a storm from one direction usually point to the cappings or eaves on that face — a useful clue when you send us photos.
We cover Caerphilly as part of Gwent, about 9 miles from Newport, Gwent.
Close by, we also cover Risca (6 miles), Pontypridd (6 miles), Blackwood (6 miles).
How much should it cost?
Most roof lantern resealing jobs come in between £245 and £495 ex VAT (£294–£594 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 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.
Roof lantern resealing in Caerphilly: questions
How do I get a price for roof lantern resealing in Caerphilly?
Send a few photos of the lantern and the problem, with your Caerphilly 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 roof lantern resealing?
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.
How much does it cost to reseal a roof lantern?
A standard-size lantern on a single-storey extension is usually £245–£495 ex VAT. Larger lanterns, difficult access or gasket replacement add to that, and you get the fixed price in writing first.
How long does resealing take?
Most domestic lanterns take a few hours in dry weather.
Other lantern repairs in Caerphilly
- Roof lantern leak repairs in Caerphilly
- Misted glass unit replacement in Caerphilly
- Cracked lantern glass replacement in Caerphilly
- Slipped glass panel repairs in Caerphilly
- Solar control and self-cleaning glass upgrades in Caerphilly
- Opening vent and actuator repairs in Caerphilly
Roof lantern resealing near Caerphilly
More about roof lantern resealing · All roof lantern repairs in Caerphilly