Ministry of Construction on the issuance of "commercial housing sales area calculation and apportionment of common building area rules" Article 8 The common building area consists of the following two parts: 1, elevator shafts, stairwells, garbage lanes, transformer rooms, equipment rooms, public *** foyers and aisles, basements, guard rooms on duty, and other functions for the building as a whole serving the building of the building of the building of the building of the public *** rooms and management buildings; 2, the set (the unit and half of the horizontal projection area of the partition walls and external walls (including the mountain wall). unit) and common building space between the partition wall and half of the horizontal projection area of the wall of the exterior wall (including the mountain wall). Excluding the floor area of the basement carport and the building area of the human defense project which is sold or rented as independent use space.