Most of the construction drawings recommend a slab recess of about 6 to 8' inside the hoistway. Special wall bracing is to be added later for the model ultimately chosen. After researching numerous elevator styles, and the hoistway requirements, I was able to give up some personal closet room as a compromise for a removable floor slab-to-attic 5' X 5' storage room.
My visionary wife thinks our new home ought to have provision for an elevator should one be needed in our hillside home, as the garage and hobby rooms are beneath the main level.