The short answer
Open the window fully and look for the data plate, a small label on the sash or the frame that carries the size code, the type and the date of manufacture. On VELUX windows it is usually at the top of the frame, behind the sash, and it shows once the window is opened. If the plate has gone, we can identify the code from the frame itself at a free survey.
Where the data plate sits
To find your VELUX code, start with the window itself. The maker fixes a data plate to every roof window, and the code that you need is printed on it. The plate is small, often no bigger than a stamp, and designed to sit out of sight when the window is closed.
These are the usual places to look, starting with the most likely.
- The top of the frame, behind the sash, visible once the window is opened.
- The edge of the sash, on the side that faces the room once the window is open.
- The inside face of the frame at the top, which you can see by tilting the sash to its widest position.
- On some older models, the inner edge of the wooden lining that sits against the plaster.
You may need a torch and a small mirror, because the label faces away from the light and from your eye line. Be careful when you open the window, and where the glass is out of easy reach do not stand on anything unstable. Ask someone to hold the steps, or leave it for the survey.
What is printed on the plate
The plate lists several pieces of information, but only a few matter for a replacement or an accessory order.
| Item on the plate | What it tells you |
|---|---|
| Size code | The width and height of the frame, for example MK04 |
| Type or model | Whether the sash is centre-pivot, top-hung or another style |
| Production date | Roughly how old the window is |
| Glazing code | The glass specification fitted in the sash |
In a code such as MK04 the letter is the width, the digits the height. If you want to see how that translates into a size, our page on VELUX window sizes explained works through it in detail.
If the plate is painted over or worn away
A plate can be hidden by paint, dirt or a decorator's tape, and on very old windows the printing fades. Try a soft damp cloth first, and avoid scraping, because a scratched label is harder to read than a dirty one.
If the label still cannot be read, a photograph often helps. Take a clear picture of the whole frame, the sash edge and any text you can see, and send it to us with the room and the roof slope noted. A photo is not a full survey, but it helps us arrive prepared. At the visit we measure the frame from inside the room and from the roof and match it to the nearest published size. That reading goes onto your written quote, so the code does not have to be guessed again.
Why the code matters before you order anything
Blinds, flashing kits, replacement sashes, glass units and electric motors are all ordered by code. A part that does not match the code does not fit, and most are made to order, so a wrong guess can cost days. Reading the code first is the quickest way to avoid that.
It also decides how simple a replacement will be. When the new window matches the code of the old one, it sits in the same opening and the rafters stay untouched. Our page on VELUX window installation and replacement shows how that fits into the wider service we offer across Coventry and the surrounding area.
What to do once you have the code
Write the whole code down exactly as printed, including any letters after the digits, and note the production date beside it. Take a photograph of the label as a record, since it is easy to misread a worn character later on.
Then decide what you want to do. If you plan to add a blind, check that the model is listed for your window type. If the sash looks tired or the glass has misted, send the code with a few photos and we can tell you whether new glass or a whole new unit is the better route. If you are thinking of a larger window, the code is your starting point, and we explain what changes at the survey. Keeping a note of the code with the house papers also saves a search the next time anything needs ordering.
What we do when we visit
At the free survey in Coventry or within 30 road miles of it, we read the plate if there is one and check it against the frame. We also look at the age of the unit, the state of the flashing and the lining, and the way the roof covering meets the frame. You receive a fixed written quote that states the code, the specification and what the finished room will look like, the opening splayed inside where the roof depth allows, with plaster and finishing to follow.
If the work involves replacing the whole unit, it counts as notifiable building work, with Part L applying to the new unit. Our team makes the Building Control notification when the work is notifiable, so the paperwork travels with the job.
