In Hanworth, 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.
About Hanworth and the TW13 area
Drier, sunnier parts of the UK are kinder to seals than the wet west, but strong sun ages sealant, gaskets and plastic end caps, and south- or west-facing lanterns can make rooms very warm. Solar control glass and an opening vent help.
Across London, many lanterns sit on rear extensions with access only through the house, so we protect floors and plan the work to keep time indoors to a minimum. Parking and any permits are factored into the quote.
We cover Hanworth as part of Greater London, about 12 miles from Westminster.
If you're just outside Hanworth, we also cover Hampton (2 miles), Feltham (2 miles), Sunbury-on-Thames (3 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?
Most lantern repairs in England need no approval at all. Where a job turns into a replacement, the Building Regulations 2010 apply and we confirm how the work will be signed off before we start. 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 Hanworth: 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.
Can you repair a lantern someone else installed in Hanworth?
Yes. We repair lanterns whoever fitted them. If yours is still under the installer's warranty, contact them first so you don't affect it.
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 Hanworth
- Roof lantern leak repairs in Hanworth
- Roof lantern resealing in Hanworth
- Cracked lantern glass replacement in Hanworth
- Solar control and self-cleaning glass upgrades in Hanworth
- uPVC roof lantern repairs in Hanworth
- Flat rooflight and skylight repairs in Hanworth
Misted glass unit replacement near Hanworth
More about misted glass unit replacement · All roof lantern repairs in Hanworth