Condensation forms when warm, humid air meets a cold surface — and a roof lantern is the coldest surface in many kitchens. It can drip like a leak but needs a completely different fix. We confirm whether it's condensation, then deal with the cause: ventilation, cold bridging at the kerb, or poor glass.
What are the signs you need condensation diagnosis and fixes?
- Water on the inside of the glass on cold mornings, even without rain
- Drips after cooking, showers or drying clothes
- Black mould at the base of the lantern lining
- Wet window sills elsewhere in the house too
What usually causes it?
High humidity
Cooking, kettles, showers, drying washing and people all add moisture to the air.
Cold surfaces
Older glass, uninsulated kerbs and un-thermally-broken frames stay cold and collect condensation.
Poor ventilation
Without trickle vents, extraction or an opening vent, moist air has nowhere to go.
How do we fix it?
- Diagnosis visitWe check for leaks, measure conditions where useful, and look at the kerb, frame and glass.
- Recommend the cause-based fixThat might be better extraction, trickle or opening vents, insulating the kerb or upgrading glass.
- Carry out what you chooseYou choose the fixes; we price each one separately in writing.
How do I know if it's condensation or a leak?
Ask: does it happen when it rains, or when it's cold? Condensation appears on cold mornings and after cooking or showers, often across the whole inner surface. Leaks follow rain and come from one place. Our guide why does my roof lantern get condensation? walks through the clues.
What should you expect to pay for condensation diagnosis and fixes?
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: sealed glass units.
Questions about condensation diagnosis and fixes
Will new glass stop condensation?
Better glass raises the inner surface temperature and helps, but if the room is very humid, ventilation matters more. We'll tell you which will make the bigger difference.
What does a condensation visit cost?
Diagnosis visits start from £145 ex VAT. Any fixes are priced separately and confirmed in writing before work starts.
Is condensation in a lantern normal?
Occasional light condensation on very cold mornings can be. Regular dripping isn't, and can damage linings and cause mould.
Where do we carry out condensation diagnosis and fixes?
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
