Tilt and turn window with hopper top light, made to measure

This window has the same split as the fixed window with tilt-in top light — a small bottom-hung sash at the top, a larger pane below — but here the lower pane is a full tilt and turn window instead of fixed glass. That means tilting at eye level for an ordinary gap, turning to open it fully or to clean it, and the tilt-in sash above for ventilation without a sash standing open at head height. Of the three narrow, tall windows (the fixed window with top light, the fixed window with tilt-in top light, and this one), this is the form with the most moving parts — and so also the most expensive in hardware.

The standard size is 1,100 × 1,800 mm, with the tilt-in sash taking a quarter of the height and the tilt and turn window the rest. Choose this window if, in a narrow, tall spot, you want both full ventilation and the option to clean the glass, not just a gap for air.

This combination suits a bathroom or bedroom with a narrow window where you still want full control: the tilt-in sash stays on its gap for everyday air, while the tilt and turn pane below can open for a thorough clean or on a warm evening. Two sets of hardware also means twice the maintenance and two sets of locks to check — in a window you rarely use, that is a reason to fall back on the simpler fixed window with tilt-in top light.

Of all 20 layouts in the window group, this is the form with the most function in the smallest width: 1,100 mm for three ways of airing the room (tilt, turn, and the tilt-in sash). If you want the same function but wider, don't look for a larger version of this window — there isn't one in our layouts — but at a double window such as the 2-pane window with two tilt and turn sashes, which puts two full tilt and turn panes side by side.

For this layout, as with the other two-part windows, measure the full height in one go, to the overall size of the frame. When deciding where it goes, allow for two things that mustn't get in each other's way: the operating rod of the tilt-in sash at the top, and the clear swing space of the tilt and turn pane below when you turn it fully open to clean it.

Maintenance on this window is the most involved of the three two-part forms: two complete sets of hardware, two sets of locks and an operating rod for the tilt-in sash all need a check now and then. Colour and finish follow the same chart as any other pane — any RAL colour on aluminium, a foil or through-colour on uPVC — and because both panes open here, it is usual to have them in the same colour so the window reads as one, despite the two different opening mechanisms.

In a renovation, people often choose this layout when the old window in the same spot already had to do two jobs — ventilating up high and opening fully for maintenance — but did so with outdated or incomplete hardware. In a new build this combination is usually specified deliberately for a bathroom or plant room where both continuous ventilation and a full opening for servicing equipment are needed.

For break-in resistance, the tilt and turn pane is the point to watch here, because its hinges and locking points always give an opening pane more points of attack than a fixed one. For a ground-floor window, ask about a stronger locking cylinder, just as with a standard tilt and turn window.

In both panes the weight of the glass counts for the hardware, more than in a window with a fixed pane. The configurator checks per pane whether the chosen glass suits the size, so you don't accidentally order a combination the hardware can't carry.

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