Do you calculate the building area of exterior wall steps and corridors?

Do you calculate the building area of exterior wall steps and corridors?

Steps are not included, and the building area is calculated based on the outer edge of the external wall. If there is no enclosure structure in the corridor, half of the projected area is used to calculate the building area. If there is enclosure structure, but the storey height is less than 2.2M, it is also considered as the general area. If it is more than 2.2M, it is calculated as the whole area