Two 150mm diameter ventilation sleeves shall be cast into the wall/s of each SS. In the case of S/C SS or scissor S/C SS, no fire rating is required for these fragmentation plates. The two ventilation sleeves shall be provided in the S/C SS or scissor S/C SS wall at the staircase entrance landing or intermediate landing at each storey or one each at the entrance landing and intermediate landing. Only ventilation sleeves of an approved design from approved suppliers shall be used.