Each glazing bar on a roof lantern has a top capping that clamps the glass onto gaskets. We carry out glazing bar and capping repairs across Gwynedd, with a guide price from your photos and a fixed price in writing before any work starts.

Signs you need glazing bar and capping repairs
- A capping visibly higher than its neighbours
- Water running down one glazing bar inside
- End caps missing at the bottom of a bar
What usually causes it?
Gasket shrinkage
Rubber gaskets shrink back from the ends over time, leaving a gap at the ridge or eaves.
Damage
Ladders, window cleaning or someone stepping on a lantern can bend a capping or unclip it.
Roof lanterns in Gwynedd
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.
What should you expect to pay for glazing bar and capping repairs in Gwynedd?
Guide price for glazing bar and capping repairs: £165–£395 ex VAT (£198–£474 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.
Glazing bar and capping repairs in Gwynedd: questions
How much do capping and gasket repairs cost?
Usually £165–£395 ex VAT per lantern depending on how many bars are affected, confirmed in writing before work starts.
Can a capping just be clipped back on?
Sometimes, if nothing underneath has failed. We check the gaskets first, because clipping a capping over a perished gasket doesn't stop the leak.
Which towns in Gwynedd do you cover?
All of Gwynedd, including Bangor, Gwynedd, Caernarfon, Dolgellau, Holyhead, Llangefni, Porthmadog. Rural and remote addresses are covered by arrangement.
How do I get a price for glazing bar and capping repairs in Gwynedd?
Send a few photos of the lantern and the problem with your postcode, by WhatsApp or the form. We reply with a guide price and confirm the fixed price in writing before any work starts.
Other repairs in Gwynedd
- Misted glass unit replacement in Gwynedd
- Cracked lantern glass replacement in Gwynedd
- Timber roof lantern repairs in Gwynedd
- Opening vent and actuator repairs in Gwynedd
- Roof lantern respraying in Gwynedd
- Urgent leak make-safe in Gwynedd
Nearby areas
- Glazing bar and capping repairs in Clwyd
- Glazing bar and capping repairs in Powys
- Glazing bar and capping repairs in Dyfed
- Glazing bar and capping repairs in West Glamorgan
- Glazing bar and capping repairs in Mid Glamorgan
More about glazing bar and capping repairs · All roof lantern repairs in Gwynedd