mechanical penthouse
A mechanical floor level at the top of a building which is set back from the building's perimeter.
The most common purpose of a mechanical penthouse is to hold the sheaves and engines for traction elevators. In these cases it ioften called an "elevator penthouse". However the terms are not synonymous, as mechanical penthouses frequently hold fan rooms and other mechanical equipment.
The need for a mechanical penthouse can be eliminated in tall buildings by the use of machine roomless elevators.