Each glazing bar on a roof lantern has a top capping that clamps the glass onto gaskets. Send photos from Derry~Londonderry (BT47) and we'll tell you which it is — with the price agreed in writing before any work.
What you might be seeing
- A capping visibly higher than its neighbours
- Water running down one glazing bar inside
- 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.
Damage
Ladders, window cleaning or someone stepping on a lantern can bend a capping or unclip it.
About Derry~Londonderry and the BT47 area
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.
If you're just outside Derry~Londonderry, we also cover Strabane (14 miles), Limavady (15 miles), Portstewart (27 miles).
Guide prices for glazing bar and capping repairs in Derry~Londonderry
Most glazing bar and capping repairs jobs come in between £165 and £395 ex VAT (£198–£474 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 Northern Ireland?
Most lantern repairs in Northern Ireland need no approval at all. Where a job turns into a replacement, the Building Regulations (Northern Ireland) 2012 apply and we confirm how the work will be signed off before we start. 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.
Glazing bar and capping repairs in Derry~Londonderry: questions
Do you cover Derry~Londonderry?
Yes. We cover Derry~Londonderry, including the BT47 postcode area, as part of County Londonderry. 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.
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.
Other lantern repairs in Derry~Londonderry
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Glazing bar and capping repairs near Derry~Londonderry
More about glazing bar and capping repairs · All roof lantern repairs in Derry~Londonderry