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. We carry out misted glass unit replacement across South Glamorgan, with a guide price from your photos and a fixed price in writing before any work starts.

Signs you need misted glass unit replacement
- Fog, droplets or white bloom between the panes
- One pane looks hazier than the others
- Water marks or tide lines inside the unit
What usually causes it?
Water sitting on the edge
If the unit's edge sits in water because the eaves don't drain, the seal fails sooner.
Movement and age
Thermal movement and age wear the seal; units at the bottom of the lantern often go first.
Roof lanterns in South Glamorgan
Western and upland parts of the UK get more rain and more wind-driven rain than the east, and that's what finds weak cappings and blocked eaves first. Lanterns here benefit from a check of the bars on the most exposed face and a clear eaves channel before winter.
What should you expect to pay for misted glass unit replacement in South Glamorgan?
Most misted glass unit replacement jobs come in between £245 and £595 ex VAT (£294–£714 including 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 South Glamorgan: questions
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.
How long does a replacement unit take?
Units are made to measure, so there's a lead time between measuring and fitting. Fitting itself is usually a short visit.
Which towns in South Glamorgan do you cover?
All of South Glamorgan, including Cardiff, Barry, Penarth, Cowbridge, Llantwit Major. Rural and remote addresses are covered by arrangement.
How do I get a price for misted glass unit replacement in South Glamorgan?
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 South Glamorgan
- Glazing bar and capping repairs in South Glamorgan
- Upstand and kerb repairs in South Glamorgan
- Aluminium roof lantern repairs in South Glamorgan
- Flat rooflight and skylight repairs in South Glamorgan
- Urgent leak make-safe in South Glamorgan
- Orangery lantern repairs in South Glamorgan
Nearby areas
- Misted glass unit replacement in Mid Glamorgan
- Misted glass unit replacement in Gwent
- Misted glass unit replacement in West Glamorgan
- Misted glass unit replacement in Powys
- Misted glass unit replacement in Dyfed
More about misted glass unit replacement · All roof lantern repairs in South Glamorgan