Each glazing bar on a roof lantern has a top capping that clamps the glass onto gaskets. When a capping lifts or a gasket perishes, rain gets under it and runs down the bar. Re-seating or replacing the capping and gaskets is one of the most effective leak repairs there is.
What are the signs you need glazing bar and capping repairs?
- A capping visibly higher than its neighbours
- Gasket rubber poking out, cracked or missing
- Water running down one glazing bar inside
- Rattling or whistling in wind
- 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.
Fixings working loose
Screws and clips that hold the capping relax with thermal movement, so the clamp on the glass weakens.
Damage
Ladders, window cleaning or someone stepping on a lantern can bend a capping or unclip it.
How do we fix it?
- Identify the barInside stains and outside checks tell us which bar is leaking.
- Remove the cappingWe lift the capping carefully and inspect gaskets, glass edges and fixings.
- Replace what's failedGaskets, fixings or the capping itself are replaced where needed; we source frame-compatible parts or use proven generic profiles.
- Re-seat and sealThe capping is refitted under correct pressure and the ends sealed.
Can you get parts for my lantern?
Many lanterns use common system profiles and parts are available. Where a system is discontinued or unknown, we use compatible gaskets and cappings or adapt the detail. We confirm the approach before you commit.
Why does water come out at the eaves when the bar is the problem?
Water that gets under a capping near the ridge runs down the bar inside the frame and appears at the lowest point — usually the eaves. That's why we check the whole bar run, not just where the drip lands.
What should you expect to pay for glazing bar and capping repairs?
Guide prices assume a standard lantern on a single-storey roof with safe ladder access. Where a tower or scaffold is needed we add it to the quote (typically £245–£895 ex VAT). Diagnostic visits start from £145 ex VAT. Your fixed price is confirmed in writing before any work starts. See all guide prices.
Where is this on the lantern?
Highlighted in amber: glazing bars, cappings and gaskets.
Questions about glazing bar and capping repairs
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.
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.
Where do we carry out glazing bar and capping repairs?
We cover the whole of the UK. Choose your area for local details and towns we cover.
England
- Bedfordshire
- Berkshire
- Bristol
- Buckinghamshire
- Cambridgeshire
- Cheshire
- Cornwall
- Cumbria
- Derbyshire
- Devon
- Dorset
- County Durham
- East Riding of Yorkshire
- East Sussex
- Essex
- Gloucestershire
- Greater London
- Greater Manchester
- Hampshire
- Herefordshire
- Hertfordshire
- Isle of Wight
- Kent
- Lancashire
- Leicestershire
- Lincolnshire
- Merseyside
- Norfolk
- North Yorkshire
- Northamptonshire
- Northumberland
- Nottinghamshire
- Oxfordshire
- Rutland
- Shropshire
- Somerset
- South Yorkshire
- Staffordshire
- Suffolk
- Surrey
- Tyne and Wear
- Warwickshire
- West Midlands
- West Sussex
- West Yorkshire
- Wiltshire
- Worcestershire
Wales
Scotland
- Aberdeen and Aberdeenshire
- Highlands and Islands
- Moray
- Dundee and Angus
- Perth and Kinross
- Fife
- Edinburgh and the Lothians
- Glasgow and Clyde
- Lanarkshire
- Ayrshire
- Stirling and Falkirk
- Dumfries and Galloway
- Scottish Borders
- Argyll and Bute
