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Quick answer: this is a brand-versus-category question. VELUX is a company — the biggest name in roof windows, so dominant that Brits say “a Velux” the way they say “a Hoover”. A skylight is any glazed opening in a roof. So every VELUX is a skylight, but plenty of skylights aren’t VELUX — and the useful distinction hiding underneath is opening roof window vs fixed rooflight.
The three words the trade actually uses
- Roof window — an opening, weather-rated window fitted in the plane of a pitched roof. This is what VELUX (and Fakro, Keylite and the other brands) mostly sell: centre-pivot or top-hung, with blinds, glazing options and escape-window variants.
- Rooflight — in most UK usage, glazing for a flat roof: a glass unit on an upstand, usually fixed, sometimes electrically opening. Bespoke and walk-on units live in this category.
- Skylight — the umbrella term (and the American default). Suppliers use it loosely for everything above, which is exactly why quotes go wrong.
Nobody polices these definitions — some suppliers say “rooflight” for pitched-roof products too. The practical rule: never order from the word; order from the spec — pitched or flat roof, opening or fixed, and the size code.
The differences that actually matter
Opening vs fixed. An opening roof window ventilates — which matters enormously in kitchens, bathrooms and converted lofts where moisture and summer heat build up. A fixed unit is cheaper for the same glass area, has no mechanism to fail, and suits stairwells and hallways where you’d never reach the handle anyway.
Pitched vs flat roof. The roof you have largely decides the product. Pitched roofs (most UK houses) take roof windows with brand flashing kits. Flat roofs (extensions, dormers) take upstand-mounted rooflights or roof lanterns.
Cost. Like for like, fixed is cheaper than opening, manual opening is cheaper than electric or solar, and standard sizes are dramatically cheaper than bespoke. A branded opening roof window runs £330–£1,230 supplied; fixed flat-roof units start lower; large bespoke glazing goes far higher.
Regulation. Identical either way: planning permission usually isn’t needed, building regulations always apply to a new opening.
So which should you buy?
Ask two questions. Does the room need ventilation? Moisture or heat → opening roof window; pure daylight → fixed unit and pocket the difference. What’s the roof? Pitched → a branded roof window (whether that’s VELUX specifically is its own question); flat → a rooflight or lantern.
And when comparing quotes, make sure everyone’s pricing the same thing — the word “skylight” on two quotes can mean a £400 fixed unit on one and a £1,500 electric roof window on the other.
Frequently asked questions
Is a Velux the same as a skylight?
VELUX is a brand name — the Danish company that dominates UK roof windows — used generically the way 'Hoover' is for vacuum cleaners. A 'Velux' in everyday speech means an opening roof window in a pitched roof; 'skylight' is the broader term covering any roof glazing, opening or fixed.
What's the difference between a rooflight, a skylight and a roof window?
In UK trade use: a roof window sits in a pitched roof, opens, and meets window standards; a rooflight usually means glazing for a flat roof, often fixed; skylight is the umbrella word for all of it. Suppliers vary, so always confirm what a quote actually includes.
Are Velux windows more expensive than skylights?
An opening VELUX roof window costs more than a fixed skylight of similar size because you're paying for the opening mechanism and hardware — plus the VELUX brand premium. Fixed flat-roof skylights start cheaper; large bespoke rooflights cost far more than any VELUX.
Which should I choose — a fixed skylight or an opening roof window?
Rooms that generate moisture (kitchens, bathrooms) or heat (lofts) benefit from an opening window's ventilation. For pure daylight in a hallway or stairwell a fixed unit does the job for less, with nothing to maintain.
Keep reading
Bespoke rooflights cost £1,000–£4,000+ supplied versus a few hundred for standard sizes. When made-to-measure is worth it — and when it isn't.
Most UK skylight installations cost £900–£2,500 per window in 2026, fully fitted. Full breakdown: supply, labour, scaffolding, flat roofs and lanterns.
Fakro, Keylite, RoofLITE+, Roto and Dakea compared against VELUX on 2026 prices, guarantees and quality — and which alternative fits which job.