Off-street parking areas for four or more vehicles may occupy front, side and rear yard areas subject to site plan approval. No parking of vehicles shall be permitted in the driveways, aisles, fire lanes, or turning areas. Nothing shall prohibit driveways for one and two-family dwellings from being considered one off-street parking space per family except that any driveway in excess of 10% slope shall not be considered as off-street parking.