The height at any point of a building or structure, except chimneys, and small dish antennas, shall not exceed 25 feet, measured vertically thereto above the original grade. Chimneys shall not extend more than five feet above any part of the building or structure. Antennas shall not extend more than 15 feet above any part of the building or structure. No accessory structure shall exceed 15 feet in height above original grade.