In Portsmouth, as everywhere, resealing is the planned, whole-lantern version of a leak repair: we cut out the old, failed sealant, clean every joint back to a sound surface and reseal the cappings, ridge and eaves with materials that suit the frame. Send photos and we'll tell you what we think has failed.

Signs you need roof lantern resealing
- Several small leaks rather than one obvious one
- Sealant applied over sealant from previous patch repairs
- A lantern that is 8–15 years old and has never been maintained
What usually causes it?
Sealant past its life
Exposed sealant on a roof takes UV, frost and constant expansion and contraction. It hardens, loses grip and pulls away from the glass.
Wrong product used
General-purpose or acetoxy silicone can fail early on some frames and coatings. Glazing joints need a low-modulus, compatible sealant.
Covering Portsmouth and nearby
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.
From Southampton to Portsmouth is roughly 15 miles — all part of the Hampshire area we cover.
Neighbouring places we cover include Gosport (2 miles), Fareham (5 miles), Ryde (6 miles).
What should you expect to pay in Portsmouth?
Typical range: £245–£495 ex VAT, which is £294–£594 with VAT, per lantern. 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.
Roof lantern resealing in Portsmouth: questions
Can you repair a lantern someone else installed in Portsmouth?
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.
Which places near Portsmouth do you cover?
As well as Portsmouth, we cover nearby Gosport, Fareham, Ryde, Havant and the rest of Hampshire.
How much does it cost to reseal a roof lantern?
A standard-size lantern on a single-storey extension is usually £245–£495 ex VAT. Larger lanterns, difficult access or gasket replacement add to that, and you get the fixed price in writing first.
How long does resealing take?
Most domestic lanterns take a few hours in dry weather.
Other lantern repairs in Portsmouth
- Condensation diagnosis and fixes in Portsmouth
- Roof lantern respraying in Portsmouth
- Flat rooflight and skylight repairs in Portsmouth
- Leak investigation and inspection in Portsmouth
- Orangery lantern repairs in Portsmouth
- Commercial roof lantern repairs in Portsmouth
Roof lantern resealing near Portsmouth
More about roof lantern resealing · All roof lantern repairs in Portsmouth