A roof lantern leak is almost always a failed seal, a lifted capping, blocked eaves drainage or a problem where the kerb meets the flat roof — not a failed lantern. We find the actual entry point, repair that, and water-test it before we leave.
What are the signs you need roof lantern leak repairs?
- Drips from a glazing bar or the eaves beam when it rains
- Brown staining or bubbling paint on the plasterboard lining around the lantern
- Water running down the inside face of the glass
- Damp patches on the ceiling a short distance from the lantern
- A leak that only appears in wind-driven rain from one direction
What usually causes it?
Failed silicone or glazing tape
UV and thermal movement break down the seal between capping, gasket and glass. Once a gap opens, water tracks along the bar and drops at the lowest point.
Lifted or misaligned cappings
Top cappings clip or screw over each glazing bar. If one has lifted, been knocked or was never seated, rain gets straight under it.
Blocked eaves drainage
Most lanterns collect water in a channel inside the eaves beam and let it out through weep slots. Leaves, moss and grit block the slots and the channel overflows indoors.
The kerb or roof junction
If the flat roof membrane isn't dressed high enough up the kerb, or the kerb has no fall, water sits against the joint and finds its way in under the lantern.
How do we fix it?
- Photos firstSend photos or a short video of the lantern and the leak. We give you a guide price and tell you whether a visit is likely to be needed.
- Trace the entry pointOn site we check cappings, gaskets, ridge, eaves and kerb, and water-test section by section where the source isn't obvious.
- Agree the fix in writingYou get a fixed price for the repair before any work starts, and nothing is added without your written agreement.
- Repair and water-testWe repair the failed detail with compatible materials, then water-test the area so you can see it holding.
Can a leaking roof lantern be repaired rather than replaced?
In most cases, yes. The frame and glass of a lantern rarely fail on their own; leaks come from the seals and details around them. A targeted repair to the affected bar, ridge or eaves usually costs a fraction of a new lantern. We only suggest replacement when the frame is distorted, the timber is rotten through, or several glass units have failed and the numbers no longer make sense.
Why does the leak only happen in some weather?
Wind-driven rain pushes water uphill and sideways under cappings that cope perfectly well with vertical rain. A leak that appears only in a south-westerly storm usually points to the bars or eaves on that face. Leaks after snow or a long dry spell followed by heavy rain often point to the eaves drainage or the kerb junction. Tell us when it leaks — it narrows the search.
Is it a leak or condensation?
Condensation forms on cold surfaces in humid rooms and appears on cold mornings, often without rain. A leak follows rainfall. If you see water on the inside of the glass on a dry, cold morning after cooking or showers, read our guide to roof lantern condensation before booking a leak repair.
What should you expect to pay for roof lantern leak 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 roof lantern leak repairs
How much does a roof lantern leak repair cost?
Most leak repairs fall between £195 and £595 ex VAT for a standard lantern with ladder access. The fixed price is confirmed in writing before any work starts.
Can you fix the leak in the rain?
We can make the lantern safe in wet weather, but sealants and tapes need a dry, clean surface to bond, so permanent repairs are done in a dry window.
Do I need to be home?
If we need to water-test or check the inside of the lantern, yes. Exterior-only work can sometimes be done with access arranged in advance.
Will you show me what was wrong?
Yes. We photograph the failed detail and the finished repair and send them to you with the invoice.
Where do we carry out roof lantern leak 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
