In Caernarfon, as everywhere, each glazing bar on a roof lantern has a top capping that clamps the glass onto gaskets. Send photos and we'll tell you what we think has failed.

What you might be seeing
- A capping visibly higher than its neighbours
- Gasket rubber poking out, cracked or missing
- End caps missing at the bottom of a bar
Why it happens
Gasket shrinkage
Rubber gaskets shrink back from the ends over time, leaving a gap at the ridge or eaves.
Fixings working loose
Screws and clips that hold the capping relax with thermal movement, so the clamp on the glass weakens.
Roof lanterns in Caernarfon
Western and upland parts of the UK get more rain and more wind-driven rain than the east, and that's what finds weak cappings and blocked eaves first. Lanterns here benefit from a check of the bars on the most exposed face and a clear eaves channel before winter.
Coastal wind drives rain hard against lanterns, so cappings and ridge seals on the seaward face take the most punishment.
From Bangor, Gwynedd to Caernarfon is roughly 8 miles — all part of the Gwynedd area we cover.
Close by, we also cover Llangefni (8 miles), Bangor, Gwynedd (8 miles), Porthmadog (16 miles).
How much should it cost?
Typical range: £165–£395 ex VAT, which is £198–£474 with 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 Caernarfon: questions
Do you cover Caernarfon?
Yes. We cover Caernarfon, including the LL55 postcode area, as part of Gwynedd. 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.
Do you need to visit to price glazing bar and capping 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.
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.
Do you repair uPVC and timber lantern bars too?
Yes. Timber lanterns use different beads and cappings, and we repair those as part of timber lantern repairs.
Other lantern repairs in Caernarfon
- Flat roof junction and flashing repairs in Caernarfon
- Solar control and self-cleaning glass upgrades in Caernarfon
- Opening vent and actuator repairs in Caernarfon
- Leak investigation and inspection in Caernarfon
- Cleaning and maintenance in Caernarfon
- Urgent leak make-safe in Caernarfon
Glazing bar and capping repairs near Caernarfon
More about glazing bar and capping repairs · All roof lantern repairs in Caernarfon