(1) General.- Copper sheets for roofing, including clips, shall be not less than 0,55 millimetres in thickness, and shall be made from hot rolled-sheet of dead-soft temper.

(2) Detailed requirements.- Copper sheets for roofing shall be laid on a deck complying with the requirements of paragraph (c) of section 12, except that timber decks may be unwrought and butt joined.