No building or structure shall exceed three stories or 40 feet in height. No building or structure which exceeds one story in height shall be located closer than 50 feet to any property abutting the lot site of the building or structure if such abutting property is zoned single-family residential or R-2 low-density multiple-residential at the time a building permit for the construction of the building or structure has been issued by the city.
(`78 Code, § 17.24.090.)