GB 51251-2017 第3.2.1条
| **** | For enclosed stairwells and smoke-proof stairwells using natural ventilation, openable exterior windows or openings with an area of not less than **1.0㎡** shall be provided at the highest part; when the building height is greater than 10m, openable exterior windows or openings with a total area of not less than **2.0㎡** shall also be provided **on the exterior wall of the stairwell within every 5 floors**, and the arrangement interval shall not exceed **3 floors**. |