For every building, structure or part thereof having over 5,000 square
feet of gross building area erected and occupied for commerce, hospital,
laundry, dry cleaning, places of public and quasi-public assembly,
industry, and other similar uses involved in the receipt and distribution
by vehicles of materials or merchandise, there shall be provided and
permanently maintained adequate spaces for standing, loading, and
unloading services in order to avoid undue interference with the public
use of streets or alleys. Every building, structure or addition thereto
having a use which complies with the above definition shall be provided
with at least one truck standing, loading, and unloading space to
the rear or side of the premises not less than 12 feet in width, 35
feet in length, and 14 feet in height. One additional truck space
of these dimensions shall be provided for every additional 20,000
square feet, or fraction thereof, of gross area in the building. No
loading or unloading shall be conducted in the front of any store.