RoofLanternsforyourextension
More natural light over your extension, without building up or out.
- 5.0★from 25 Google reviews
- CertifiedAssure Insurance-backed
- 10+ YearsExperience
- GuaranteedFor 10 Years
What a roof lantern does to an extension
Light from above, without building up or out.
The roof lantern photograph is a genuine Wilshaw installation. The other two images are illustrative stock, not photographs of a completed Wilshaw roof-lantern job.
Planning permission & Building Regs
Will the council actually let you fit one?
Most roof lanterns on a standard flat-roof extension fall under permitted development, so usually you won't need planning permission for the lantern itself. Real exceptions: going over the height limit, a listed property, a conservation area with an Article 4 direction, or a flat or maisonette. One honest correction: Part O overheating rules don't apply to extensions, only to new residential buildings.
- Permitted development covers most standard extensions, with real exceptions for listed buildings and conservation areas
- The U-value ceiling that actually applies to a rooflight is 2.2 W/m²K
- Always worth confirming with your local planning authority before committing to a design
The structural opening
Does your extension need a steel beam?
When a lantern opening crosses existing joists, the cut joists need trimming: doubled or tripled members either side, so the roof carries the same load as before. A modest opening is often manageable with timber trimmers. A wider span more often needs a structural steel beam, always assessed by a structural engineer or qualified builder, never assumed.
- A modest opening can often be trimmed with doubled or tripled timber members
- A wider span more often needs a structural steel beam, assessed properly, not guessed
- Building control inspects this detail before it's covered, because it's a genuine structural alteration
What is your extension roof built on?
The answer decides whether standard trimming is enough, or a beam is needed.
A standard timber-joisted flat roof
Prone toA modest single-opening lantern.
How we treat itUsually manageable with doubled or tripled timber trimmers.
A wide-span or open-plan extension
Prone toAn opening crossing several joists at once.
How we treat itMore often needs a structural steel beam, always assessed properly first.
An existing glazed roof being converted
Prone toReplacing polycarbonate or glass panels with a lantern opening.
How we treat itAssessed for structural capacity the same as a new opening, never assumed either way.
Not sure which is yours? Send us a photo, or book a survey and we'll tell you.
Lantern, flat rooflight or skylight: which is right for your extension?
All three let light in from above. Which suits your extension depends on the roof and how much light you want.
| Roof lantern | Flat rooflight | Skylight | |
|---|---|---|---|
| How it sits on the roof | Raised, prism or pyramid shaped | Sits flush, minimal from inside | Fits into the roof plane |
| How much light it lets in | Most of the three, roughly 3x a vertical window | Good, less than a lantern | Good, depends on size |
| Typical cost position | Usually the most expensive | Sits below a lantern | Varies by size and roof type |
| Pitched-roof suitability | Flat and low-pitch only | Flat and low-pitch only | Can go into a pitched roof too |
Swipe to see every column
What we actually do
We supply and fit aluminium roof lanterns to flat-roof extensions, working alongside a builder or architect you already have on site, or as a stand-alone job.
Comfort, not a greenhouse
Will it turn your room into a greenhouse? Here's what actually stops that
Self-cleaning glass uses a UV coating that breaks down organic dirt, which rain washes away, cutting manual cleaning to roughly once a year. It's low-maintenance, not never-clean. Solar control glass reflects over 60% of solar energy, cutting summer heat gain, glare and UV fade without blinds doing the whole job alone.
- Self-cleaning glass cuts manual cleaning to roughly once a year, honestly explained
- Solar control glass reflects over 60% of solar energy, cutting heat and glare
What's wrong with the roof you've got now
Common, ordinary stuff, not a hard sell.
A dark, boxy extension
A flat-roof extension with no real daylight beyond what comes through the walls.
Old polycarbonate
A rooflight that's yellowed over time, or started leaking at the joints.
The wrong glass
A previous lantern specified with the wrong glass, turning the room into a greenhouse in summer.
How it works, start to finish
No salesman, just the job done properly.
The survey
Josh comes out himself, looks at your extension roof and talks through what it can take.
The quote
You get a written, fixed quote with the structural and glass details already worked out.
The fit
We open the roof, fit the lantern and make good around it, working with your builder if you've got one.
The bits people worry about
Will you and my builder clash on site?
We're happy to work alongside an existing builder. It's a normal part of the job for us.
What if something is found once the roof is opened up?
The survey catches most issues early. We'll never promise there won't be a surprise, but we'll flag what we can beforehand.
How long is my extension open to the weather?
We open, fit and weather it back up as one continuous job on the day.
Why people pick us, and why your builder will be glad we did
Josh surveys and manages every job himself, the same person from quote to finish. We're happy to supply and fit the glazing alongside an existing builder or architect, not take over your whole project. Every job carries an Assure insurance-backed guarantee.
- Owner-led, one point of contact from enquiry to finish
- We supply and fit the glazing, happy to work alongside your builder
- Assure insurance-backed workmanship guarantee on every job
Roof lanterns, explained properly
Condensation forms when moist air inside the room meets cold glass with nowhere to escape. A lantern with no ventilation traps that moisture, and over time it can lead to mould around the frame.
Modern lantern designs address this with integrated trickle vents in the roof plate, or mechanical ventilation, alongside the Building Regs duty to ventilate where the extension joins the original building. Worth asking about at quoting stage, not once the room feels damp.
Cost
What actually drives the cost of a roof lantern
Every job is quoted
We don't publish a price list because a lantern's cost genuinely depends on the opening, the structure and the glass. Book a survey and we'll come back with a written, fixed quote.
- The opening size, and whether a steel beam is needed
- Glass specification: self-cleaning, solar control, or both
- Whether we're fitting alongside an existing builder or taking the job on as a stand-alone project
What our customers say
Read the reviews for yourself on our Google profile.
5.0
Andy
Josh installed our new windows, triple track doors, roof lights and front door at our house in Bournemouth. A very professional, tidy and efficient service from beginning to end. Would highly recommend Wilshaw Glazing.
Daniel Hunt
Had two Velux windows installed in our loft conversion. The workmanship is spot on and it's reassuring to know everything is Assure certified with a 10-year warranty. Josh was easy to get hold of whenever I had questions. Very pleased.
AKI 95
Very happy with our skylights installed by Josh, very professional, Polite and very clean and has changed our whole kitchen I very highly recommend if you are from Bournemouth or Surrounding areas
How much do roof lanterns cost?
It depends on the opening, the structure and the glass, so we don't publish a fixed price. Book a survey for a written, fixed quote.
Are roof lanterns a good idea?
Fitted with the right glass, yes: they're the most light-giving of the roof-glazing options. The wrong glass, not the lantern itself, is what causes a greenhouse effect.
What's the best roof lantern?
It comes down to the glass specification and how well the flashing matches your roof, more than any single brand. We'll talk you through it at survey.
Will it make the room too hot in summer or cold in winter?
Solar control and self-cleaning glass are both aimed at exactly this. See the comfort section above for how each one works.
Do I need permission for a roof lantern?
Most standard extensions fall under permitted development, so usually no. See the planning section above for the real exceptions, and check with your council if there's any doubt.
Where we fit roof lanterns
Covering Poole, Bournemouth and the surrounding towns.
Planning an extension, or already mid-build?
Tell us about your roof and we'll talk you through planning, structure and glass, then give you a fixed quote.
Get a free quote
Tell us what you need and we'll come back with a price. No pressure, no hard sell.
Prefer to talk, or email? Call Wilshaw Glazing on 01202 156 611 or email Josh.Critchley@wilshawgroup.com