Ceiling-slide doors, for when there is no headroom

A rolled curtain needs a barrel above the opening. Where the structure will not give up that space, the curtain runs back across the ceiling instead.

A conventional shutter stores its curtain on a barrel above the opening, and that barrel needs headroom — usually a few hundred millimetres of it, sometimes more.

A ceiling-slide door removes the barrel. The curtain is drawn up the guides and then back along a horizontal track under the ceiling, so the only space it needs is space that is already there.

It is the answer in a low-clearance warehouse, an under-croft car park, or any bay where a beam sits directly over the opening. It also runs quieter than a rolled curtain, because nothing is being wound.

The trade is track: the door needs a clear run inside the building roughly as long as the opening is tall, and that run has to be kept clear of services for the life of the building.