Roof Lantern Costs UK (2026): Prices, Brands & Whether They're Worth It

A roof lantern costs £2,000–£5,000 fitted for most kitchen-extension sizes in 2026 — the lantern itself from around £700 at the entry end to £4,000+ for large glazed areas, plus £1,000–£2,500 installation depending on how much structural work the opening needs. Large and bespoke designs go well beyond. Here’s where the money goes, which brand to shortlist, and when the cheaper alternative is honestly the better call.

The cost breakdown

Ranges per MyJobQuote’s roof lantern guide and Toughened Glass Systems’ 2026 price data, with entry pricing from current Korniche retail listings; checked July 2026. For a configured estimate alongside other skylight types, use our cost calculator.

What moves the number: size (glass area scales price fast), glazing spec (solar-control and self-cleaning add hundreds but earn their keep — see the FAQ on overheating), colour (non-standard RAL shades cost more), and above all the opening — cutting and trimming a new hole in a flat roof, with steels if the span demands them, is where quotes diverge.

The brands worth shortlisting

Korniche — the market’s value-and-speed pick. Machined aluminium with perfectly symmetrical glazing bars, and a clip-fit assembly system installers love because it goes together in a fraction of the usual time (less labour on your quote, too). Entry sizes from around £700 make it the default starting point.

Atlas — the architectural pick: the slimmest sightlines going, engineered to span large openings without tie bars, and 200+ RAL colours including dual-colour frames to match bifolds. You pay a little more for the minimalism.

UltraSky — the volume alternative, widely stocked; solid but generally outpointed on thermal finesse and detailing by the two above, per independent comparisons.

Thermally there’s little between the leaders — both Korniche and Atlas achieve U-values around 1.2 W/m²K with thermally broken frames and insulated units, per GFD Homes’ head-to-head. Buy on design, colour and installer familiarity rather than the datasheet.

Lantern vs flat glass: the honest question

For the same opening, a flat glass rooflight costs less, insulates better (less frame, less surface area), never collects debris in valleys, and disappears into the roofline. The lantern buys you height, light from four angles, and a focal point — it’s an architectural feature you’ll see from the garden and under from the dining table. If the room needs drama, buy the lantern; if it just needs daylight, flat glass delivers more of it per pound. (Bespoke glazing is a third path, with a third path’s price tag.)

Practicalities

• Planning: on a new extension the lantern is assessed as part of the extension’s permitted development (height limits apply); adding one to an existing flat roof usually exceeds the 150mm rooflight allowance, so check with your planning authority first.
• Building regs: always — structural opening plus Part L glazing. Installers who handle sign-off save you the building-control dance.
• Kerb detail: the upstand and its waterproofing tie-in decide whether the lantern leaks in year three. Insist the quote itemises it, as with any skylight job.
• Access: most lanterns go onto single-storey rear extensions — scaffolding is often modest or avoidable, one of the few cost mercies in this category.