In the office, hotel or similar ceiling is not more than 3m tall and that's perfect. In warehousing ceiling is higher and it depends on what kind of things are in the warehouse. Maybe you want to minimize cell coverage and you would not install APs on the ceiling, but maybe you need to. WLAN design is not trivial. You need to try, get experience and reading some books certainly doesn't hurt.
I have installed an AP 40m up and walked 60m away from it and still had good connection.
Primoz points are important. All installations will vary with environment. An
outdoor 7762 is typically mounted on light poles or outside 2nd floor of bldgs,
with dome down. An indoor 7982 can be ceiling mounted (over wall mounts),
and can also be placed on top of book cases or filing cabinets, in a one-story
office building, and still radiate good lateral coverage. Mounting on the ceiling
of two-story office buildings may radiate above and below sufficiently. But a
pre- and post-installation site survey, measured to your desired data rates, is
always the best advice to determine AP coverage.