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 Chalk Farm (NW3) 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
Why it happens
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.
About Chalk Farm and the NW3 area
Sun and UV do more damage than rain on many lanterns here: brittle ridge caps, chalky finishes and hardened gaskets. They're cheap to replace before they let water in.
London's extensions are often tight to neighbouring walls and roofs. Where a repair needs access over a neighbour's property, we'll tell you in advance so you can arrange it.
From Westminster to Chalk Farm is roughly 3 miles — all part of the Greater London area we cover.
We also cover nearby Camden Town (1 mile), Holloway (1 mile), Archway (2 miles).
How much should it cost?
Guide price for misted glass unit replacement: £245–£595 ex VAT (£294–£714 inc 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 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.
Misted glass unit replacement in Chalk Farm: questions
Do you cover Chalk Farm?
Yes. We cover Chalk Farm, including the NW3 postcode area, as part of Greater London. 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.
Which places near Chalk Farm do you cover?
As well as Chalk Farm, we cover nearby Camden Town, Holloway, Archway, Kilburn and the rest of Greater London.
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.
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 Chalk Farm
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Misted glass unit replacement near Chalk Farm
More about misted glass unit replacement · All roof lantern repairs in Chalk Farm