Height. The maximum height of any building shall be 35 feet, except that such height may be increased when approved as a special exception by the Zoning Hearing Board for such structures as water towers, silos, chimneys, steeples, radio and television antennas, elevator towers, solar collectors, and air-conditioning units, provided that for every five feet of height in excess of 35 feet, there shall be added to each yard requirement one corresponding foot width or depth.