Condensation forms when warm, humid air meets a cold surface — and a roof lantern is the coldest surface in many kitchens. We carry out condensation diagnosis and fixes across Cornwall, with a guide price from your photos and a fixed price in writing before any work starts.

Signs you need condensation diagnosis and fixes
- 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.
Poor ventilation
Without trickle vents, extraction or an opening vent, moist air has nowhere to go.
Roof lanterns in Cornwall
Damp, mild winters keep moss and algae growing on flat roofs and lantern frames, which holds water against seals and blocks weep slots. Regular clearing makes a real difference in wetter areas.
Near the coast, salt in the air is hard on aluminium finishes and fixings; washing the frame occasionally and touching in chips keeps corrosion away.
What should you expect to pay for condensation diagnosis and fixes in Cornwall?
Typical range: £145–£495 ex VAT, which is £174–£594 with VAT, per visit. 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 England?
Straightforward repairs — resealing, gaskets, cappings, eaves and like-for-like parts — don't normally need building regulations approval in England. Replacing the whole lantern or enlarging the opening is different and falls under the Building Regulations 2010; we confirm in writing which route applies before any replacement. Listed buildings need listed building consent from the local council for alterations, and conservation areas can have extra controls; like-for-like repairs are treated differently from changes, so check with the council's conservation officer first.
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.
Condensation diagnosis and fixes in Cornwall: questions
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.
Which towns in Cornwall do you cover?
All of Cornwall, including Truro, Redruth, Falmouth, St Austell, Camborne, Newquay. Rural and remote addresses are covered by arrangement.
How do I get a price for condensation diagnosis and fixes in Cornwall?
Send a few photos of the lantern and the problem with your postcode, by WhatsApp or the form. We reply with a guide price and confirm the fixed price in writing before any work starts.
Other repairs in Cornwall
- Roof lantern leak repairs in Cornwall
- Roof lantern resealing in Cornwall
- Upstand and kerb repairs in Cornwall
- Flat rooflight and skylight repairs in Cornwall
- Orangery lantern repairs in Cornwall
- Commercial roof lantern repairs in Cornwall
Nearby areas
- Condensation diagnosis and fixes in Devon
- Condensation diagnosis and fixes in Somerset
- Condensation diagnosis and fixes in Bristol
- Condensation diagnosis and fixes in Dorset
- Condensation diagnosis and fixes in Wiltshire
More about condensation diagnosis and fixes · All roof lantern repairs in Cornwall