For commercial, industrial and public and semi-public buildings and uses of more than five thousand (5,000) square feet of gross floor area, space either inside or outside the building for the loading and unloading of goods and materials shall be provided. Such space shall not be less than ten feet wide, twenty-five (25) feet long, nor less than fifteen (15) feet in height if covered. Such space shall be provided with direct access to an alley or street.