A. 
No building, structure or land shall be used and no building or structure shall be hereafter erected, structurally altered or enlarged, except for the following uses:
(1) 
Reservation.
(2) 
Forestation.
(3) 
Recreation.
(4) 
Accessory use and building, customarily incident to any of the above uses, on the same lot and not involving the conduct of a business.
B. 
The following uses are permitted only as a conditional use requiring approval of the Zoning Hearing Board:
(1) 
Water tank, flagpole or open structure necessary to the proper functioning of and appurtenant to the above uses.
(2) 
Radio-television transmission or receiving tower and facilities.
On each lot not occupied by a building or structure and on each lot upon which a building is hereafter erected, enlarged or repaired, there shall be provided and maintained a lot area, yards and other open spaces which shall be not less than prescribed as follows.
A. 
Front yard depth: not less than 20 feet.
B. 
Side yard widths.
(1) 
Interior lot: not less than three feet on each side of the main building.
(2) 
Corner lot: not less than 20 feet on all yards abutting on a street or alley.
(3) 
Rear yard depth: not less than 20 feet. (Exclusive of any portion of depth to be used for permitted accessory uses or buildings.)