For a long time, There was a famous building in the Washington DC area that did no demolition of existing conditions when doing renovations. The construction just lowered the corridor ceilings to accommodate new stuff. When it was finally gutted for a complete renovation there was 10 feet above ceiling crammed with pipes, ducts, and wiring and 9.5 feet in the usable space below.
For a long time, There was a famous building in the Washington DC area that did no demolition of existing conditions when doing renovations. The construction just lowered the corridor ceilings to accommodate new stuff. When it was finally gutted for a complete renovation there was 10 feet above ceiling crammed with pipes, ducts, and wiring and 9.5 feet in the usable space below.