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 from Cwmbran (NP44) and we'll tell you which it is — with the price agreed in writing before any work.

What you might be seeing
- Fog, droplets or white bloom between the panes
- One pane looks hazier than the others
- Water marks or tide lines inside the unit
Common causes we find
Edge seal failure
Every sealed unit has an edge seal and desiccant. Once the seal fails, humid air gets in and the desiccant saturates.
Water sitting on the edge
If the unit's edge sits in water because the eaves don't drain, the seal fails sooner.
About Cwmbran and the NP44 area
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.
We cover Cwmbran as part of Gwent, about 5 miles from Newport, Gwent.
Close by, we also cover Pontypool (3 miles), Risca (5 miles), Newport, Gwent (5 miles).
How much should it cost?
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 Cwmbran: questions
Do you cover Cwmbran?
Yes. We cover Cwmbran, including the NP44 postcode area, as part of Gwent. Send photos by WhatsApp or the form for a free guide price, and we'll confirm the fixed price in writing before any work starts.
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.
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.
Other lantern repairs in Cwmbran
- Roof lantern leak repairs in Cwmbran
- Upstand and kerb repairs in Cwmbran
- Cracked lantern glass replacement in Cwmbran
- Condensation diagnosis and fixes in Cwmbran
- Roof lantern respraying in Cwmbran
- Cleaning and maintenance in Cwmbran
Misted glass unit replacement near Cwmbran
More about misted glass unit replacement · All roof lantern repairs in Cwmbran