No building or structure shall be erected, substantially altered, or its use changed unless permanently maintained off-street parking and loading spaces have been provided in accordance with the provisions of this Zoning Ordinance.
(a) The provisions of this chapter, except where there is a change of use, shall not apply to any existing building or structure. Where the new use involves additions or enlargements, there shall be provided as many of such spaces as may be required by this Ordinance.
(b) Whenever a building or structure constructed after the effective date of this Ordinance or amendment herein is changed or enlarged in floor area, number of employees, number of housing units, seating capacity, or otherwise to create a need for an increase in the number of existing parking spaces, additional parking spaces shall be provided on the basis of the enlargements or change, provided whenever a building or structure existing prior to the effective date of this Ordinance is enlarged to the extent of fifty percent (50%) or more in floor area, number of employees, number of housing units, seating capacity or otherwise such building or structure shall then and thereafter comply with the full parking requirements set forth herein.