2-pane window with one tilt and turn sash, made to measure

Of the double windows, this is the most chosen split: one pane stays fixed and keeps the view unbroken, the other is a full tilt and turn window. So you don't have to choose between a large piece of glass and being able to air the room — you get both, in one frame with one mullion. In the configurator you choose whether the tilt and turn pane goes on the left or the right.

The standard size is 1,800 × 1,500 mm, split equally between the two panes. If you need more ventilation than one tilt and turn pane gives, the 2-pane window with two tilt and turn sashes — with a tilt and turn pane on both sides — is the broader choice; if you want no opening at all, the 2-pane fixed window is the simpler one.

This is the split you'll find in most Dutch living rooms, where this window comes from, and that is no accident: one wide fixed pane keeps the garden or the street in view, while the tilt and turn pane beside it stays small enough not to get in the way of a sofa or a table. If you're choosing between left and right, look at the route people walk through the room and at which side has the fewest obstacles for a sash turning open.

Compared with a window of the same overall width without a fixed pane — two tilt and turn panes, as in the 2-pane window with two tilt and turn sashes — you save on hardware here and so on price, at the cost of only being able to air and clean on one side. For a room with another source of ventilation, such as a door or a mechanical system, that is often enough; for a room that relies on this window alone, the 2-pane window with two tilt and turn sashes may be the better choice.

For this layout, measure the full width of the opening in one go; which part stays fixed and which part turns, you specify separately in the configurator. When deciding where it goes, allow for the swing space of the tilt and turn pane — count on the full sash width plus a margin, so the sash doesn't hit a piece of furniture, a radiator or an adjoining window once it is fully open.

Maintenance is limited to the one tilt and turn pane — the fixed pane beside it needs nothing. Colour and finish follow the same chart as any other pane, and most people choose the same colour for both panes, so the mullion stays the only visible difference between the fixed and the opening part. If you'd rather show which part opens, a subtly different colour on the sash can emphasise it — that is a matter of taste, not a technical requirement.

In a renovation, this is the most chosen replacement for an old window that already had this split, because the layout of the room is already arranged around it. In a new build the split between fixed and tilt and turn is often decided the other way round: first you look at which part of the room deserves the most unbroken view, and only then where the tilt and turn pane fits best without interrupting it.

For break-in resistance, the tilt and turn pane is the point to watch on this window; the fixed pane beside it has no hardware to get a grip on. For a ground-floor window, ask about a stronger locking cylinder on the tilt and turn pane.

In the fixed pane you can use the heaviest glass with no consequences for hardware; in the tilt and turn pane, weight counts for the hardware carrying the sash. The configurator checks this per pane as soon as you enter the size and the glass.

Still not sure? Use the comparison with the other layouts in this group above to see which arrangement suits your situation best.