"Floor area" is used in this title as a basis for requiring off-street parking for any structure. Unless otherwise stated, the area applies not only to the ground floor area, but also to any additional stories or basement of the structure, including enclosed porches, but shall exclude exterior load-bearing walls and columns, rooms housing mechanical equipment incidental to the operation of the structure, elevators and shafts, stairways and stairwells.
(`78 Code, § 17.04.258.) (Ord. 1675 § 1, 1983.)