In older housing the question is whether there is a cavity. Here it is
whether the cavity is allowed to be touched.
01 Engineered trusses
Most of the housing built here since the 1990s has a trussed roof. Truss chords are structural and cannot be cut for a lift box, which rules out the obvious solution on a great many ceilings and pushes the work into a dropped soffit or a coffer.
02 Vaulted ceilings
Handsome, and hostile to concealment. No flat plane, no accessible cavity, and a mounting height that puts everything out of reach. The mechanism nearly always ends up at floor level instead.
03 Finished basements
The opposite problem, in the best way. Dropped ceilings, open joist space, straightforward wire routing, and a room already built for a screen. This is where projector lifts and screen cassettes belong.
04 Post-2000 great rooms
Two-storey walls with a fireplace in the middle and nowhere sensible for a television. Usually solved with a lift in the millwork below rather than by mounting anything at height.