Roof Lantern Cost UK: 2026 Prices for Kitchen Extensions & Flat Roofs

A roof lantern transforms a flat-roof extension from a dark, awkward space into the light-filled heart of the home. They've become the default finish on rear kitchen extensions across the UK — and on a typical 4m x 6m single-storey rear extension, fitting one is often the single biggest decision affecting how the space feels.

This guide covers what roof lanterns cost in the UK in 2026, the difference between uPVC, aluminium and timber frames, and what to factor in beyond the headline lantern price.

Roof Lantern Costs: At a Glance

Most homeowners on a typical kitchen extension fit a 3m x 2m or 3m x 3m aluminium lantern, typically landing at £3,500–£5,500 fully installed. Timber lanterns command a substantial premium and are most often chosen for heritage or character properties.

What's Included in the Installed Price

A typical fully-fitted roof lantern price includes:

• The lantern itself (frame and glazed units)
• Delivery to site
• Lifting and positioning onto the prepared upstand
• Sealing to the existing flat roof or kerb
• Disposal of packaging

What's usually not included:

• Building the structural upstand (roofer or builder, typically £300–£700)
• Internal plastering of the reveal (plasterer, typically £150–£300)
• Scaffolding or access equipment (£200–£800 if needed)
• Painting or staining of timber lanterns

Most lantern suppliers offer "supply only" prices around 30–40% lower than the installed price, but unless you have an experienced fitter lined up, the installed quote from a specialist is usually better value.

uPVC vs Aluminium vs Timber

The frame material is the single biggest cost driver after size.

uPVC — The cheapest option, typically used on smaller lanterns up to 2m x 2m. Bulkier frames mean less glass area for a given footprint. Acceptable thermal performance but limited size range and a less premium look. Best for budget-conscious projects on modest extensions.

Aluminium — The most popular option for modern extensions. Slim sightlines (the visible frame profile is thin), large pane sizes available, excellent thermal performance with polyamide thermal breaks, and a contemporary look that suits most kitchen extensions. Powder-coated in any RAL colour — anthracite grey is overwhelmingly the most popular choice. Typically lasts 30+ years with minimal maintenance.

Timber — Premium option, usually engineered laminated timber. Best for heritage properties, conservation areas and character renovations. Costs roughly 50–80% more than aluminium for an equivalent size. Requires repainting or restaining every 5–8 years to maintain weather resistance.

What Drives the Final Price

1. Size. Doubling the area roughly doubles the price. Larger lanterns also need larger glazed units, which become disproportionately expensive once individual panes exceed 1.5m x 2m.

2. Glass specification. Standard double glazing is the baseline. Common upgrades:

• Self-cleaning glass — Photocatalytic coating that breaks down organic dirt; useful on sloped panes you can't easily reach. Adds 15–25%.
• Solar control (tinted) — Reduces heat gain in summer; useful on south-facing lanterns over kitchens, which can otherwise become uncomfortably hot. Adds 10–20%.
• Triple glazing — Improves thermal performance, particularly relevant in colder regions or for Passivhaus-style builds. Adds 15–30%.

3. Opening sections. Many lanterns include a single opening vent for ventilation. A motorised vent with rain sensor adds £600–£1,200 over a fixed lantern. Worth considering for kitchens, where extract ventilation matters.

4. Colour and finish. Standard aluminium colours (anthracite grey, white, black) are included in the base price. Bespoke RAL colours typically add 10–15%.

5. Site access. Lanterns over 3m wide may need a small crane or telehandler to lift into place — £200–£600 depending on access.

Roof Lantern vs Other Skylight Options

For a flat-roof extension, you have three main options:

• Roof lantern — Pyramid- or hipped-shaped, frame visible from below, premium look
• Flat rooflight — Single flush pane, modern minimalist look, typically cheaper than a lantern of equivalent size
• Multiple Velux-style fixed skylights — Cheapest option, more frame visible from inside

A 3m x 3m flat rooflight typically costs £2,500–£4,500 installed — somewhat cheaper than an aluminium lantern of the same size, but with less architectural interest. The choice often comes down to interior design preference rather than cost.

Planning Permission and Building Regulations

Most roof lanterns fitted to an existing flat-roof extension are covered by permitted development rights and do not require planning permission. The main exceptions:

• Conservation areas or listed buildings
• Extensions facing a highway
• Locations where existing PD rights have been removed

Building Regulations always apply to thermal performance (U-value typically 1.4 W/m²K or better) and structural integrity. A reputable lantern supplier will provide the relevant certifications; your builder or roofer will handle the structural sign-off.

Avoiding Common Pitfalls

1. The upstand is critical. A lantern can only be as watertight as the kerb it sits on. Insist on a properly built and waterproofed timber or insulated upstand, sealed to the EPDM, GRP or felt below.

2. Don't undersize the lantern. Many homeowners fit a smaller lantern than the extension can support, then regret it. As a rough rule, the lantern should be at least one-third the footprint of the extension to feel like a true feature.

3. Specify solar control on south-facing lanterns. Without it, kitchens under a large lantern can hit uncomfortable temperatures on summer afternoons.

4. Plan the electrics. If you want a chandelier or pendant hanging from the lantern centre, the structural lantern will usually need a small fixing point — easier specified at order time than retrofitted.

Find a vetted local roofer or extension specialist to fit your lantern at Local Roofer Directory.

FAQ

How long does roof lantern installation take? On a prepared upstand, a typical aluminium lantern goes in within half a day. Including the upstand construction and internal making good, the whole process usually spans two to three days.

Will I need scaffolding? For most ground-floor rear extensions, no — the lantern can be lifted into position from the flat roof. Two-storey extensions or restricted-access sites may need a small tower or telehandler.

How much glare is there from a roof lantern? A south-facing lantern over a kitchen will be very bright on sunny days. Solar control glass, internal blinds and careful positioning of seating areas all help. Many homeowners fit motorised blinds within the lantern frame.

Can a lantern be added to an existing flat roof? Yes, provided the roof structure can take the load (most can) and an upstand can be built. The flat roof covering then needs to be properly cut and re-sealed to the new upstand. Always use the same roofer or a specialist for this — DIY cut-ins are a leading cause of lantern leaks.

How thermally efficient are modern roof lanterns? Modern aluminium lanterns with thermal breaks and argon-filled double glazing typically achieve U-values of 1.2–1.4 W/m²K — broadly equivalent to a high-quality window. Triple-glazed options can hit 1.0 or below.