Stairs are calculated according to the projected area in Zhejiang Province quota. When calculating, it is calculated according to the projected area of each floor of the stairs, and then summarized. The components of stairs include stair board, stair board beam, stair mouth beam, platform beam, platform and stairwell. But those that extend into the wall are not counted, and then the clear width of the stairs multiplied by the projection length is the projection area of the stairs? It's very simple, but I didn't know how to calculate it until a teacher explained it. I study pedagogy in Hangzhou Gaobo. If you want to learn, you can also go there for consultation. Anyway, the traffic is convenient, and you can get there by subway.