In Swansea, as everywhere, if a roof lantern pane looks cloudy or wet between the two layers of glass, the sealed unit has failed and moisture has got inside. Send photos and we'll tell you what we think has failed.

Is it time for misted glass unit replacement?
- One pane looks hazier than the others
- Misting that comes and goes with the weather
- Water marks or tide lines inside the unit
What usually causes it?
Edge seal failure
Every sealed unit has an edge seal and desiccant. Once the seal fails, humid air gets in and the desiccant saturates.
Movement and age
Thermal movement and age wear the seal; units at the bottom of the lantern often go first.
Covering Swansea and nearby
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.
We also cover nearby Gorseinon (5 miles), Neath (7 miles), Port Talbot (7 miles).
Guide prices for misted glass unit replacement in Swansea
Typical range: £245–£595 ex VAT, which is £294–£714 with VAT, per glass unit. 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 Wales?
In Wales, like-for-like repairs to a roof lantern don't usually involve building control. A full replacement or a bigger opening is controlled under the Building Regulations 2010 (as applied in Wales), so we set out the route in writing first. Listed buildings in Wales need listed building consent from the local planning authority for alterations, with Cadw guidance on historic buildings; check with the council 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.
Misted glass unit replacement in Swansea: questions
Do you need to visit to price misted glass unit replacement?
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.
Which places near Swansea do you cover?
As well as Swansea, we cover nearby Gorseinon, Neath, Port Talbot, Llanelli and the rest of West Glamorgan.
How much does a misted lantern unit cost to replace?
Usually £245–£595 ex VAT per unit depending on size, glass spec and access, confirmed in writing before work starts.
Will the new pane match the others?
We match tint and coatings as closely as possible; a new unit can look very slightly clearer than older neighbours.
Other lantern repairs in Swansea
- Roof lantern leak repairs in Swansea
- Eaves beam and gutter repairs in Swansea
- Upstand and kerb repairs in Swansea
- Solar control and self-cleaning glass upgrades in Swansea
- Condensation diagnosis and fixes in Swansea
- Opening vent and actuator repairs in Swansea
Misted glass unit replacement near Swansea
More about misted glass unit replacement · All roof lantern repairs in Swansea