Required side and rear yards may be occupied by an accessory residential garage for uses normally associated with residential garage use and other permitted accessory buildings, structures or use, provided that such accessory buildings, structures or use shall be situated not less than five feet from any lot line, that such accessory buildings, structures or use shall be at least five feet from the principal building and that such accessory buildings, structures or use shall not exceed 15 feet in height, except that swimming pools shall be located at least 15 feet from the principal building and they shall not encroach into the required side yards.