On the same premises with every building or use involved in the receipt or distribution by vehicle of materials or merchandise, there shall be provided and maintained on the lot adequate space for standing, loading and unloading services in order to avoid undue interference with public use of streets or alleys. Such space, unless otherwise adequately provided, shall include a ten (10) foot by twenty-five (25) foot loading space with fourteen (14) foot clearance for every twenty thousand (20,000) square foot or faction thereof in excess of three thousand (3,000) square feet of land used for the above-mentioned purposes. (PZSC § 03-12-018)