Will Your Existing Blinds Fit a Replacement Roof Window?

Usually not. Existing blinds rarely fit a replacement roof window, even when the new window carries the identical size code, because blinds are sized to the window generation, not just the size letter and number. When the frame profile changes between generations, and it does roughly every ten to fifteen years, the side channels and top brackets that a blind clips into move with it. Your old MK06 blind and your new MK06 window can share a size code and still not mate. That mismatch is one of the most common surprises in a roof window replacement, so it belongs in your budget from the start rather than arriving as an afterthought. This page explains what usually transfers, what does not, and how to plan for it.

Apex Skylights replaces roof windows across Ipswich, Suffolk and north Essex. Our installers have 25 years fitting VELUX, Keylite and Roto units. We raise the blind question at survey, because a set of good blackout blinds across three loft windows is a real cost, and people reasonably assume it carries over.

Two numbers describe your window, and blinds care about both

People think of a roof window by its size code, the letter-and-number like MK06 or PK10. That code sets the structural opening, the width and height of the gap between the trimmed rafters, and it has been broadly stable for decades. If size codes were the whole story, every MK06 blind would fit every MK06 window ever made. They do not, and the reason is the second number nobody quotes: the generation.

A generation is a version of the frame design. Every ten to fifteen years the manufacturer redesigns the sash and frame profile, moving the hardware fixing points, the glazing bead and, critically for blinds, the geometry of the recess and the top rail that a blind bracket engages. The size code stays MK06 because the structural opening has not changed. The frame the blind actually touches has changed completely. So a blind is really sized by two things at once: the size code, which sets the width and drop of the fabric, and the generation, which sets how and where it clips on.

If you do not know your size code yet, our find your VELUX size code page shows where the data plate sits and how to read it, and VELUX size codes explains what each letter and number means. What the codes do not tell you directly is the generation, and that is exactly the part that governs whether a blind transfers. More on how to read the whole plate is on VELUX window codes explained.

What usually transfers, and what does not

Not every accessory is equally fussy. The rule of thumb is simple: the more precisely an accessory clips into the frame profile, the less likely it is to survive a generation change. Fabric and drop can be reused in theory; brackets and channels almost never can.

Blackout blinds are the ones people most want to keep, because they are the dearest and because a loft bedroom without one is unusable on a June morning. They are also the least forgiving. The side channels are cut, drilled and screwed to a specific frame profile, so a generation change leaves them landing on the wrong geometry. Pleated and simple roller blinds, with lighter top fixings, are the most likely to adapt, and even those often need new brackets. Factory-integrated blinds, where the blind lives inside a purpose-made sash, cannot be carried over at all, because that sash is a different product from a standard replacement.

How to budget for it

The window is the main cost and the blinds are a secondary line, but on a multi-window loft the blind line is not trivial. Plan for it deliberately.

1. Count the openings that need covering. A single landing window may not need a blind at all. A south-facing loft bedroom with two or three roof windows needs blackout on every one, and that is the line that adds up.
2. Match the blind type to the room, not to what you had. If the old room had roller blinds and struggled with morning light, a replacement is the moment to move to proper blackout side-channel blinds. You are buying new either way.
3. Choose blinds with the window, so the generation is right first time. Because the blind is sized to the new window’s generation and size code together, ordering them alongside the window guarantees they clip straight on. Buying blinds separately later, off the old size code alone, risks a mismatch even though the code looks right.
4. Factor the finish decision in. A white polyurethane sash for a bathroom pairs with a moisture-tolerant blind fabric. It is a small point, but it is another reason to specify blinds and window as one order.

We do not mark blinds up as a hidden profit line, and we state on the quote whether blinds are in scope or not, so you are never guessing. If they are outside the scope of the work, we still tell you the generation and size code so you can order the right ones yourself.

As a rough guide for the budget conversation, a good blackout side-channel blind is the dearest type and a light pleated blind the cheapest, with roller blinds in between. Across a three-window loft bedroom, blackout blinds on every opening are the line that moves the total, so it is worth deciding early whether you need blackout everywhere or only on the windows that face the morning sun. A north-facing landing window may need nothing at all. We will tell you which of your windows genuinely warrant blackout, because there is no sense buying the most expensive blind for an opening that never catches direct light.

Why this points back to replacing the window, not nursing it

The blind question only arises because roof window frames change generation, and the same generation changes are why an old window cannot simply be patched. A frame profile that no longer matches current blinds is a frame profile whose sashes, gaskets, hinge sets and sealed units are equally out of production. If your blinds no longer fit anything on sale, that is a strong sign the window itself is a generation or two past its parts availability, and the route is replacement of the whole unit, not repair. The obsolete-parts problem in full is on our VELUX window replacement page.

So the blind that will not transfer is not really the problem. It is the messenger. It is telling you the window has aged into a generation whose parts are gone, and the practical answer is a new window, chosen with new blinds sized to it, done in one visit. On a like-for-like swap that is a one-day job, the roof watertight the same day, with a 10-year workmanship guarantee behind it.

Common questions about blinds and replacement windows

Get a fixed price, blinds included in the plan

Send a photograph of the data plate on the top edge of the sash, one of the window from inside, and tell us what blinds are on it now. We can then say whether a like-for-like replacement fits, whether your blinds have any chance of transferring, and what the whole job, window and blinds together, is likely to cost. Then we survey, confirm the opening and the flashing kit, and give you one written price with the blind position stated clearly.

That price is fixed, and every installation carries a 10-year workmanship guarantee. Request a fixed quote for a replacement VELUX in Ipswich, Suffolk or north Essex, or see our published prices across every service first. The parent topic is covered on our VELUX window installation hub.