The answer
An opening skylight is called a roof window when it sits in a pitched roof, and a venting rooflight when it sits on a flat one. Both have a sash that opens. Fitted with a motor they become electric opening rooflights, sometimes sold as automatic vents or smoke vents.
Two words for one idea
The homeowner's word is skylight. The trade's word is rooflight. Both point at glass in a roof, and neither tells you whether it opens. That is why a search for the name of an opening skylight turns up a handful of different answers.
The short version is this. If the glass sits in a slope, the product is a roof window. If it sits on a flat roof, the product is a rooflight, and one that opens is a venting rooflight. A lantern whose panes open is a vented lantern. We use skylight and rooflight in the same breath, because customers and tradespeople use both.
The names you will meet
Different suppliers and installers label the same idea in slightly different ways. These are the names that turn up in quotes and brochures.
| Name | Roof | Meaning |
|---|---|---|
| Roof window | Pitched | Glazed sash set into the slope |
| Venting rooflight | Flat | Rooflight with a sash that lifts |
| Opening rooflight | Either | General term for glass that opens |
| Vented lantern | Flat | Lantern with an opening pane |
| Electric rooflight | Either | Opening glass worked by a motor |
| Automatic vent | Either | Motorised vent on a sensor or timer |
Why a roof window is not the same as a flat rooflight
The two are built for different jobs. A roof window is a complete unit made to sit in the line of a pitched roof. The roof covering is dressed around the frame with flashings, and the sash turns or swings inside a frame that is already weatherproofed.
A flat rooflight is fixed to an upstand, a raised kerb built around the opening, with the glass set at a slight fall so water runs off. The sash lifts clear of the kerb on arms. Because the two are assembled differently, they also meet Part L through different limits: Approved Document L, Table 4.2, asks for 1.4 W/m²K (or WER band B) from a roof window, and 2.2 W/m²K from a rooflight.
If you are not sure which you have, look at the roof. A slope means a roof window. A flat top means a rooflight.
What the word electric adds
Electric describes how the sash is worked, not what the product is. A roof window or a venting rooflight can be opened by hand or by a small motor. With a motor, the glass answers a wall switch, a remote or a sensor.
A rain sensor is the add-on people ask about first, and our answer on whether electric rooflights close in the rain deals with it. A timer or a heat sensor can also open the vent on a warm day. These extras are worth raising early, because they change the wiring.
When you ask for a quote, say which of these you mean. Asking for an electric opening rooflight gives us the whole picture in a few words.
Using the right name when you ask
You do not need the trade vocabulary to get a good quote. Describe the room and the roof, and say that you want the glass to open. We will translate that into the right product.
- For a pitched loft or landing, ask for a roof window that opens.
- For a flat-roofed kitchen or extension, ask for a venting rooflight.
- For a tall room with a flat roof, ask whether a vented lantern would suit.
- For glass you cannot reach, ask for it to be electric.
The electric opening rooflights hub gathers these options in one place, and the question of whether you can get a skylight that opens covers the basics.
Words to bring to a survey
- Pitched or flat roof?
- Hand pole or motor?
- Rain sensor wanted?
- Blind to match?
Names on a quote and what they mean for you
A written quote should name the product plainly. Look for the roof type, the operation and the size. A line such as venting rooflight, electric, with a rain sensor, tells you the glass lifts, a motor works it and a sensor can shut it.
Size matters too. Roof windows from VELUX carry a code such as MK04, where the letter is the width and the digits are the height. A flat rooflight is described by the size of the opening or the size of the glass instead. If a quote leaves out the size, ask for it, because the size decides how much sky you gain.
Look for the finish as well. Plastered reveals, a neat splay into the ceiling and a painted frame are what turn a hole in the roof into part of the room. We put the inside finish in the quote, so you see it before you agree to anything.
What happens next
Once you know the name, the next step is the survey. We visit, measure the opening, look at the structure and talk through the options. Surveys cost nothing, and the written quote after one is fixed. The fitting is quick, the inside is finished tidily, and the guarantee on the workmanship runs for 10 years in writing.
If you want to see how the cost is built up, read what moves the price. To talk it through, WhatsApp 07880 284133 or email info@vertexskylightsmiltonkeynes.co.uk.
A few more names
Is a roof window the same as a VELUX?
VELUX is a manufacturer, and the name has become a shorthand for roof windows in general. A roof window from any maker does the same job. Sizes in the VELUX range are coded such as MK04, where the letter is the width and the digits are the height.
Is a skylight the same as a rooflight?
In everyday speech, yes. Householders say skylight, while the trade says rooflight. Both mean glass set into a roof.
What is a smoke vent?
A smoke vent is a motorised opening designed to release smoke from a stairwell or common area. It is a separate product from a homeowner's opening rooflight, and we would discuss the need at survey.
