Do VELUX windows come with glass fitted?

The window comes boxed as a complete sash and frame. Inside the sash is a sealed double or triple glazed unit, bonded in at the works, tested and warranted as a single product. You cannot see a join you are meant to finish. The pane, the spacer bar, the gas fill between the panes and the seal around the edge are all done before it leaves the factory, which is the only way the manufacturer can guarantee the argon stays in and the unit does not mist up between the panes.

That is different from how a bare frame or a made-to-measure rooflight sometimes arrives, where the glazing is a second item that goes in afterwards. A VELUX roof window is not built that way. The model code you order already carries the glazing choice inside it, so two windows of the same outer size can be very different products depending on the pane specification printed on the label.

What this means in practice is that the decision about the glass is made at the ordering stage, not at the roof. Once the box is opened there is nothing left to specify. If the glazing is wrong for the roof it is going into, the fix is a different window, not a different pane.

VELUX sells the same window shell with a range of sealed units behind a two or three letter pane code, and this is the part worth slowing down on. The standard clear unit is fine for a shaded or north-facing roof. There are laminated inner panes for safety and sound, obscured glazing for a bathroom, and, the one that matters most on this stretch of coast, a solar-control unit that cuts the heat coming through the glass.

That last option exists because glass has a G-value, the share of the sun’s energy it lets through as heat. A clear double glazed unit sits somewhere around 0.6, meaning most of the solar energy hitting it ends up warming the room. A solar-control pane pulls that down towards 0.3 or a little under. Same window, same size, roughly half the summer heat. On a south-facing roof that gap is the difference between a room you can sit in during July and one you cannot.

Southend faces south across the estuary, so the rear roof slopes and flat-roof extensions round here catch sun from mid-morning until it swings west, with reflected light off the water adding to it. A window ordered with the standard clear pane will let that straight in. So the useful question is not really whether the glass comes fitted, because it always does. It is which sealed unit you asked for before the order went in. We go into that choice in more depth on our page about energy-efficient skylight installation, because getting the pane code right at order stage is far cheaper than living with the wrong one.

The glass is fitted, but a working installation needs more than the window itself, and those parts are ordered alongside it rather than built into the sash. The main one is the flashing kit, the weatherproofing collar that seals the window to the surrounding roof covering. VELUX supplies different flashings for slate, for plain tile, for deep-profile tile and for a low-pitch roof, and the right one depends on what your roof is made of. A window without its matching flashing is not weathertight, so this is not an optional extra.

The other items that come separately are the internal lining that finishes the reveal inside the room, any blind you want, and, on an electric or solar-powered model, the control and rain sensor. None of these change the fact that the pane is already fitted. They sit around the window rather than inside it.

• Flashing kit. Matched to your roof covering and pitch. Separate order, not optional.
• Insulation and underfelt collar. Seals the gap between the window frame and the roof structure.
• Internal lining. Finishes the plasterboard reveal around the opening.
• Blinds and controls. Added to taste; the manual, electric and solar versions differ here.

Because the unit is sealed and bonded into the sash at the factory, you do not swap the pane the way you might change a single-glazed sheet in an old frame. The glazing and the sash are one warranted product. If a sealed unit ever fails, where the gas escapes and condensation appears trapped between the panes, the answer is a replacement sash or a replacement window, and putting a new unit in is a job for the manufacturer’s parts, not a pane cut to size at a merchant.

This is exactly why the specification matters before the order rather than after. If you inherit a VELUX window with clear glazing over a room that bakes every afternoon, you are not looking at a quick pane change. You are looking at replacing the unit with one that carries the solar-control glass, which is proper installation work and the moment to get the G-value right. Swapping a tired or wrongly specified window for a better-glazed one is a straightforward replacement, and it is worth doing at the point the old one is coming out anyway, because the opening and the flashing line are already there.

Start with the roof, not the window. Note which way the slope faces, whether the room below already runs hot in summer, and roughly how big an opening you want. Those three things decide the pane code far more than the size does. A north-facing landing can take the standard clear unit and be glad of the winter warmth. A south-facing rear bedroom or a kitchen extension wants the solar-control pane specified from the outset.

If you would rather hand that judgement over, tell us the orientation and the rough size and we will come back with the right VELUX model, the matching flashing for your roof and a price. Our VELUX window installation page sets out how we work, and you can ring 01702 898232 or request a quote and we will look at the whole roof rather than just the opening. Get the glazing right on paper and the window arrives with exactly the glass you need already fitted, which is the whole point of ordering it as one unit.