Dwellings: two (2) spaces per unit, not in any required front or side yard, at least one (1) of which shall be in a garage or carport, unless otherwise specified. However, when required parking is provided in a detached garage or carport, the parking space may be located in the interior side yard, but not closer than three (3) feet from the property line. Any garage or carport entrance fronting on any lot line, except an alley, shall be a minimum of twenty (20) feet from such line. For alleys, the minimum setback for an entrance facing an alley is five (5) feet.