Every part of a required yard shall be open to the sky and unobstructed except for permitted accessory buildings and except for ordinary and customary projection of sills, belt courses, cornices, and other ornamental features and unenclosed steps and unwalled stoops, porches, and carports, which may project up to three feet into a required yard. No projection into a required court which is provided in connection with a court apartment shall be constructed except for customary sills, belt courses, and cornices which may extend into the court not more than sixteen inches. (Prior code § 27-3-5)