Is there a difference between a rooflight and a skylight?

Stand under any window that looks up instead of out, and you can call it either. Skylight is the everyday word: it covers anything glazed set into a roof, from a small pane over a landing to a run of glass across an extension. Rooflight is the same object described by the people who make it, sell it, and write the rules for fitting it. Open a manufacturer's catalogue, a builder's spec sheet, or the Building Regulations themselves, and "rooflight" is what you find. Ask a homeowner what they want fitted over the bed, and "skylight" is usually the word that comes out first.

Neither word describes a fixed shape. A rooflight can be flat, pitched, fixed shut, or hinged to open. A skylight can be any of those too. The words sit on top of the object; they do not define it. That is worth knowing before you read a brochure or a quote, because the moment a word starts to feel technical, it is easy to assume it means something narrower than it does.

Skylight is the older term in ordinary English, used for centuries for anything that lets daylight fall from above: a lantern over a stairwell, a lay-light in a corridor ceiling, a dome over a hall. It stayed the word people reached for at home, long after the trade around it grew more precise.

Rooflight came later, alongside the standard sizes, kerbs and glazing units the modern trade builds around. It is the word you meet in a structural engineer's drawing, in a Building Control application, or in the small print of a warranty, because it names the product as a category rather than as a feeling of light in a room. Neither word is more correct. One grew up in the home, the other in the workshop and the spec sheet, and both point at the same glass.

Two related terms sit next to them and are worth telling apart. A roof window usually means an opening unit set into a pitched roof, in the rafter line, with a hinge so it can be pushed open from inside. A roof lantern means something else again: a raised, multi-sided glazed structure that sits proud of a flat roof, with its own small ridge and hips, rather than glass laid flush into the slope. Both are still, in the loosest sense, skylights. Both are also rooflights. The narrower words just say more about shape and how the unit sits.

The confusion people actually run into is not between "skylight" and "rooflight" as words. It is between the general sense of either word and the narrow sense a particular supplier has decided to give it. One company's quote might use "skylight" for anything glazed overhead and "rooflight" for the specific flat unit over a flat-roof extension. Another might do the reverse, using "rooflight" as the catch-all and reserving "skylight" for a smaller, simpler pane. A third might avoid both and only ever say "roof window", because that is the term their particular product range uses on the box.

None of these choices is wrong on its own. The trouble comes when a homeowner reads two quotes side by side, assumes the words mean the same thing in both, and ends up comparing a flat rooflight over an extension with a pitched roof window over a loft bedroom, without realising the two are physically different products.

The fix is simple: ask what the glass sits in and how it is shaped, rather than trusting the word alone. "Is this a flat unit laid into the roof deck, or an opening window in the pitch?" settles the question faster than any amount of arguing over terminology.

Whichever word ends up on your paperwork, the thing that actually changes your day is what you see when you look up through the glass, not what the product is called. A slim-framed rooflight and a bulky, badly placed skylight can sit in the same opening and give you completely different views of the sky: one a wide, clean rectangle, the other a sky cut into pieces by a deep frame and a bar across the middle.

That is the question we start from, regardless of which word a homeowner walks in using. Where does the frame edge fall from the pillow, the sofa or the sink. Does a glazing bar sit dead centre in the line of sight, or off to one side where it goes unnoticed. Is the reveal shaped so the opening below the glass widens the view rather than narrowing it to a letterbox. Our guide to frame profiles and sightlines goes into how much a frame can take out of the sky, and every type of rooflight and skylight compared lines the main products up against each other on exactly this basis.

We use rooflight and skylight interchangeably through this site, because that is how people actually search for and talk about the glass over their heads. Where it helps to be precise, we use the narrower trade terms: roof window for an opening unit in a pitched roof, roof lantern for a raised structure on a flat roof, and product names such as VELUX where a page is specifically about that range. You can see the full spread on our pages for roof window installation, VELUX window installation, flat roof rooflight installation, roof lantern installation, and sun tunnel installation, which covers the one product in the range that is not really a window at all.

What stays constant, whatever word is used, is the way we plan the job. Every quote comes with a sightline sketch, a drawing of the view from the place in the room that matters, showing where the frame and any bars fall and how much open sky you actually get. You can read how that drawing is put together on the sightline sketch page. Every installation is carried out to current Building Regulations, with the Building Control notification handled on our side where the work is notifiable, and backed by a 10-year workmanship guarantee. If you want to talk through what to call the glass over a particular room, and what it will actually look like once it is in, book a home visit and we will bring a tape measure rather than a glossary. Our Peterborough rooflight and skylight page and our guide to what a skylight reveal is are good next stops if you are still weighing up terms before you weigh up products.

Is a roof window the same as a rooflight?

A roof window is a rooflight, but a narrower kind: it is specifically an opening unit set into the slope of a pitched roof, usually hinged so it can be pushed open from inside. Rooflight is the wider word that also covers fixed, flat and lantern-style units.

Is VELUX just another word for skylight?

No. VELUX is a manufacturer's brand name for a range of roof windows and flat rooflights, not a general term. People sometimes use the brand name loosely for any pitched roof window, in the way some brand names get used for a whole category, but plenty of skylights and rooflights on the market are not VELUX products.

Does it matter which word I use when I ask for a quote?

Not for getting a quote started. It matters more once you compare quotes, because two suppliers may use "skylight" or "rooflight" to mean slightly different products. Describe the room, the roof shape and where you sit or lie underneath it, and let the installer confirm which product that points to.

Is a roof lantern a type of skylight?

In the loose, everyday sense, yes: it is glazing set above a room rather than beside it. In the trade sense it is its own product, a raised, multi-sided structure with a ridge and hips, built for a flat roof, and quite different in shape and cost from a flat rooflight laid straight into the roof deck.