Decks attached to or abutting a principal building shall be permitted in rear yards and/or in the rear half of side yards only. For the purposes of this subsection, in cases where all or any portion of a deck is located above any portion of the principal building, the aforesaid yard restrictions shall be applied as if such building portion did not exist beneath such deck. Patios attached to or abutting a principal building shall be permitted in rear yards only. Such decks and patios shall conform with all setback requirements applicable to the principal building, pursuant to §
18A-5 of the Land Use Procedures Ordinance, except as provided in Subsection
b of this subsection. Nothing in this subsection shall be construed to apply to or limit the construction of normal and customary residential porches, verandas, porticos or similar roofed structures.