VELUX or another roof window brand?

Roof windows from different makers do the same basic job. They let in light, open for air and keep the weather out. The differences are in the detail.

Sizes and shapes

Every maker builds its own set of sizes. They overlap, but they are rarely identical, so a window from a different maker may not sit exactly in the old opening.

Opening styles

Some windows pivot at the middle, some hinge at the top, and some do both. How the two opening styles differ is set out on that page. Which one suits depends on the room, the pitch and how you reach the handle.

Glazing

The glazing options differ in insulation, noise, solar control and safety. A laminated inner pane is standard where the glass sits over living space. Compare the U-value on the specification sheet, remembering that a roof window in an existing dwelling in England must meet a limiting U-value of 1.4 W/m²K, or WER Band B.

Accessories

Blinds, flashing kits and controls are often made by the same maker and are not always interchangeable. A blind bought for one make may not fit another.

It is possible to put a different make in the opening of a VELUX. It is not a plug-in swap, though.

The opening

If the new window is slightly narrower, the gap round it is closed up. If it is slightly wider, a small amount of trimming is needed. The unit should sit snug between rafters. Our guide to VELUX size codes explains the footprint behind each reference.

The flashing

A kit made by one maker is not designed for another maker's frame. The new window comes with its own, and the covering around it is re-laid to suit.

The rules

If the new unit is bigger, you have a new opening. On a house, Class C allows a rooflight that projects no more than 150mm beyond the plane of the roof slope, and sits no higher than the highest part of the roof. In a flat, planning permission is the route for a new rooflight, so ask the council. Where the work is notifiable, we handle the Building Control notification.

A window is not a one-off purchase. You may want another beside it in a couple of years, or a blind for the summer.

A range you can add to

If the maker keeps its sizes in production for a long time, a second window of the same code is simple to match. If the range changes, the second window may sit a little differently from the first.

Spares and accessories

Check that blinds, covers and flashing kits for your window are easy to order. The survey takes account of what is available for your covering.

Why it affects a Tyneside loft

In a Tyneside flat the upstairs owner often lights one loft room with a pair of windows, and may add a second room later. Choosing a range that stays available means the later windows can match the first, which keeps the roof looking tidy from the street. A house with a rear extension has the same issue when a second slope is added.

Ask before you commit

Ask whether the flashing kit for your covering, the blind and any electric control are listed for the model in your quote. If one of those is missing from the range, it is easier to learn that now than after the sash is in. The page on what moves a price explains how those extras enter the quote.

We do not tie a house to one name. We start with the house, then the roof, then the room, and choose the unit that fits all three.

What goes into the decision

The opening and rafters set the footprint. The covering sets the flashing. The room sets the opening style and the glazing. The make follows from those, and from what you prefer.

What you get on paper

After the free survey comes a fixed written quote that names the window. The written quote stays put unless the work alters. Workmanship carries a 10-year guarantee, also written. See VELUX windows for the range we work with, or ask for a survey.