Well here's some theater history trivia:
Way back in olden dayes, in the quaint hamlet of New York City, say 1970's, the real estate market was starting to get really hot. Many developers were looking at all that "air space" above all those Broadway and once-were-Broadway-theaters-that-were-now-porno-film-houses (42nd street in the old days) and decided that the air space was wasted space.
Trouble was, the fly towers above the stages required that nothing be built on top of the
stage, as the standard code compliant method for removing
smoke from a fire ("far" to you southerners) on-stage, was to have roof mounted doors/windows that would open in a fire. Thus all theaters with fly towers had roofs with nothing on top.
One new office building going up in mid-town got a tax break to put in a theater inside the building, part of an effort by the city to retain the theater community in the mid-town area. Note that this was 20 years before "Broadway" became a viable industy all it's own. Thus the tax break for building/keeping a theater.
The first test case was the American Place Theater, which had a theater in the basement. Not much
fly tower, as that was way too much floor space to give up (to a non-profit theater company), but certain city codes had to be modified in order to allow for both
smoke evacuation, once handled by rooftop doors, as well as the requirement for a replacement for a
fire curtain, which could not be installed due to no
fly tower.
Thus was born (in NYC at least) a motorized fan
smoke evacuation
system, powered off an emergency generator, as well as a water deluge curtain (think of a sprinkler
system on steroids) in place of a
fire curtain.
The result was a number of new theaters built - The Gershwin ("Formerly the Uris and occupying six stories of the new Uris Building") , The Minskoff ("perched on the third floor of One Astor Plaza, the fifty-five-story office tower"),
etc...
Deluge
curtains are a disaster as a concept and articles have been written about the advantage of a solid old-style
fire curtain, that can physically prevent scenic elements from falling
thru to the audience chamber and today NYC allows a real
fire curtain as an alternative to a deluge, for theaters with fly towers. Fan systems are required though.
Good thing as my spaces get to keep the fire
curtains, when we were told we needed deluge.
Steve B.