1. Determine the slope: according to the characteristics of the building, the plane position of the stairs and the specifications of the stairwell, determine the size form and appropriate slope of the stairwell. Basically determine the step width b and the step height h (note: b≮bh≯hmax, b and hmax are the step width and height of various buildings respectively. )

2. Determine the width: determine the ladder width b and staircase width according to the staircase size. Determine the curse of the cascade series, adjust the cascade height and the cascade width b, and divide the cascade height h by h to get the cascade series n ≈ h/h. When it is considered low, take an integer, adjust the cascade height h(h≈H/n), and use the formula b+h=450(mm) or b+2h = 600 ~ 620 (mm) to determine. Determine the width of the rest platform. Note (step size). According to the width b of the step and the number of steps, the horizontal projection length l of the step is determined.

3. Main parameters: the specifications of each part of the stairs are determined according to the depth and clear width of the stairwell, the height and width of the steps on each floor, the length and width of the steps and the width of the platform. (Note: The steps on each floor of the double-run stairs are even, so the steps of the two runs are the same.

4. Drafting: According to the above specifications, the first floor, the second floor and the top floor plan of the stairs are drawn by the manuscript. Determine the structure and structural form of stairs, determine whether the stairs are cast-in-place or prefabricated, whether the steps are floor slabs or beam slabs, and the support mode of platform slabs.

5. Check the clearance height of stairs to meet the clearance height requirements. When entering and exiting under the bottom platform, verify whether the clearance height under the platform beam meets the requirement of 2m. If it is not satisfied, it can be adjusted as follows: reduce the elevation of plastering layer under platform beam at the bottom of stairs. Lift the bottom flight a few steps. The ground floor is set to go straight to the second floor. Moderately increase the operating slope and raise the elevation of the bottom platform.