French casement window in Gealan S 9000 MD

Gealan S 9000 MD is the German version of the same S 9000 system that our Dutch versions Base, Haax, Slim and Styl are built on. The difference is in how the window closes and opens. MD stands for Mitteldichtung, a centre seal: there are three sealing levels between outer frame and sash. The profile is 82.5 mm deep, has 6 chambers and takes glass up to 52 mm. The Uf is 0.89 W/m²K, against 1.10 for the Dutch Base, Haax and Slim. It is a window that opens inwards: tilt and turn, side-hung, tilt-only or a door, but no window that opens outwards, whether top-hung or bottom-hung. If you want a window that opens outwards, the Dutch S 9000 is where you end up.

The German S 9000: 82.5 mm, centre seal and Uf 0.89 W/m²K.

New build. Suitable, and at Uf 0.89 the best-insulating Gealan profile we offer. Do bear in mind that all the windows open inwards.

Renovation. Suitable. At 82.5 mm frame depth the frame sits less far into the wall than the 120 mm S 9000 versions.

Gealan S 9000 Slim. The same 82.5 mm frame depth, the same 74 mm outer frame and the same 119 mm in view, but the Dutch version: a rebate seal instead of a centre seal, and windows that can also open outwards. The Uf is 1.10 against 0.89 here. Choose the Slim if you want a window that opens outwards, top-hung or bottom-hung.

Salamander bluEvolution 82 MD. Also a German profile with a centre seal and 6 chambers, with almost the same frame depth: 82 mm. It takes thicker glass, up to 60 mm against 52 mm, and is wider in view: 123 mm against 119 mm. The Uf is 0.98 against 0.89.

In a French casement, two sashes meet without a mullion that stays fixed in the frame: open, it is almost a pair of doors.

A standard double window has a mullion that stays in place even when the sashes beside it open. A French casement doesn't have one: both sashes are hinged at the outer edges and close against each other in the middle with a draught seal, not against a fixed mullion. Closed, it looks like an ordinary double window; open, the whole width is clear, with no mullion in the way. If you're replacing an existing window without a mullion, you'll recognise this form straight away: it is the one that recreates that look.

Both sashes here are side-hung casements that open inward, not tilt and turn: you get the full opening, but not the tilt position for an ordinary gap. The standard size is 1,600 × 1,500 mm. If you want the same wide opening with a tilt position on one or both sides, look at the standard double windows (the 2-pane window with one tilt and turn sash, the 2-pane window with two tilt and turn sashes), which have a fixed mullion.

All about the Gealan S 9000 MD profile All about the french casement window layout