Roof windows are the one common window where the usual measuring advice doesn’t apply. A blind for a VELUX, Fakro, Keylite or similar window is made to fit that window’s size, not your measurements. You find a code on the window, order by it, and the blind clips into place. Most people can do it themselves. The hard part is usually getting up there safely.

This guide covers loft and pitched-roof windows that open. Fixed flat-roof rooflights, lantern roofs and conservatory roofs use different products, and those are often worth a specialist’s visit.

Find the size code first

Every mainstream roof window has a data plate (also called a type sign or identification label). Open the window and look along the top of the opening sash. On VELUX windows it’s in the right-hand corner, behind the ventilation flap. VELUX says every roof window it has made since 1968 has one (VELUX’s type sign help page, checked October 2026). Fakro describes its label as showing the window type, dimensions and production code.

Write down everything on the plate, not just the part that looks like a size:

  • the window type (for example GGL or GPL on a VELUX);
  • the size code. VELUX codes look like MK06 or PK08;
  • any letters after the numbers. Retailers that sell Keylite blinds warn that a code such as 04A is not the same size as 04;
  • the production code or year, because some blinds only fit windows made in certain years (see below).

Take a photo of the plate with your phone. You’ll want it when you order.

No plate, or you can’t read it?

Plates get painted over, or they fall off when a window is replaced. Each retailer then has its own fallback, usually a chart that matches the size of the visible glass to a code. Measure exactly what their guide asks for (glass, or frame), in millimetres, and if your numbers fall between two sizes, ask them before you order. Don’t guess. A roof blind that’s slightly wrong doesn’t fit at all.

Branded or own-brand blinds?

You have two routes:

  • The window maker’s own blinds. VELUX’s blinds are made for VELUX windows. VELUX says most install in a few minutes without extra tools or a professional (VELUX’s blackout blinds pages, checked October 2026).
  • Own-brand blinds from made-to-measure retailers. Make My Blinds lists skylight blinds for VELUX, Fakro, Keylite and Dakstra/RoofLITE windows, and other retailers sell similar ranges. They’re usually cheaper than the window maker’s own blind.

Neither is automatically better. Compare like for like:

  • Blackout: does the fabric run in side channels? Without them, light leaks round the edges, which matters in a bedroom.
  • Operation: a top bar you pull down, or a rod for windows you can’t reach?
  • Fit: is your exact window type and size code listed? Some blinds only fit windows from certain years, and some are only sold for older windows, so check the production year on your plate too.
  • Warranty and returns: made-to-measure blinds usually can’t be returned just because you ordered the wrong code.

Which type of blind?

  • Blackout blinds are the usual choice for bedrooms in a loft. Look for side channels (see above).
  • Roller and pleated blinds filter light and give privacy where full darkness doesn’t matter: landings, bathrooms, home offices.
  • Venetian blinds let you angle the light, and suit bathrooms.
  • Electric or solar blinds are worth thinking about for windows you can’t reach. Solar ones charge from a small panel and come with a remote. Wired electric ones need a power supply, and that wiring is a job for a qualified electrician.

Roof windows face the sky, so they tend to let in more heat in summer and lose more in winter than an upright window of the same size. A blind helps with both, within limits. The thermal and blackout blinds guide explains what to expect.

Fitting: DIY or pay someone?

Blinds made for a specific roof window are designed for DIY. Typically, you clip the top into brackets or fixing points at the head of the window, pull the blind down and clip it into the side channels or bottom fixings. Some window makers fit those brackets as standard; on others you may need to screw them in. Read the instructions for your window and blind before you start, not after.

The real risk is height. A roof window over a stairwell or a double-height room means a ladder in an awkward spot, both hands up and an angled sash over your head. VELUX’s own advice is to make sure you can reach the window safely before you even look for the plate. Pay someone, or use a proper platform, when:

  • the window is over a stairwell or more than a step-ladder’s reach;
  • you’d have to lean out from the ladder to reach the far side;
  • you want a wired electric blind (you’ll need an electrician anyway);
  • the plate is missing and you’d rather someone else took the risk of getting the size wrong. A measure-and-fit service does exactly that.

Otherwise, for a window you can reach from a stable step-ladder, fitting yourself is quick. The DIY vs professional comparison and cost guide cover the trade-off in general.

Child safety

Most roof window blinds operate with a bar or handle rather than a cord, which removes the main hazard. VELUX says its manual blinds are cordless. If a blind for a high window comes with an operating rod, store it out of children’s reach. If any blind you’re considering has a cord or chain, the rules in the child-safe blinds guide apply in full.

In short

  1. Open the window and photograph the data plate.
  2. Choose the window maker’s blind or a retailer’s own-brand one, and check your exact type and code is listed.
  3. Order by code, not by tape measure, unless there’s no plate.
  4. Fit it yourself if you can reach safely. Otherwise pay someone.

Still deciding what goes on your other windows? The which blind for which window chooser covers every common window and room.

Frequently asked questions

Do I need to measure a VELUX window for a blind?

Usually not. Roof window blinds are made to fit a specific window size, so you order by the window's type and size code from the data plate on the top of the sash. Only measure if the plate is missing or unreadable, and then follow the retailer's own instructions, which normally ask for the glass or frame size.

Where is the size code on a roof window?

On a plate or label on the top of the opening sash, visible when you open the window. VELUX says its type sign is in the right-hand corner of the top sash, behind the ventilation flap, on every roof window it has made since 1968.

Do roof window blinds need drilling?

Most don't. Blinds made for a specific roof window clip into brackets or fixing points on the window itself. Some window makers fit those brackets as standard; others may need them screwed in, so read the fitting instructions for your window and blind before you order.

Are non-VELUX blinds as good as genuine VELUX blinds?

They can be. Several UK retailers sell own-brand blinds made to fit VELUX, Fakro, Keylite and Dakstra/RoofLITE windows. Compare like for like: blackout side channels, the frame or bar, how it's operated, and the warranty. Then check your exact window code is listed.