商品房分摊的公用建筑面积主要由两部分组成：1.电梯井、楼梯间、垃圾道、变电室、设备室、公共门厅和过道等功能上为整楼建筑服务的公共用房和管理用房的建筑面积；2.各单元与楼宇公共建筑空间之间的分隔以及外墙（包括山墙）墙体水平投影面积的50%。公用建筑面积不包括任何作 Public buildings apportioned by commodity houses are mainly composed of two parts: 1. Public houses and management houses that serve the whole building function such as elevator shaft, stairwell, garbage road, transformer room, equipment room, public hall and aisle 2. The separation between each unit and the public building space of the building and 50% of the horizontal projected area of ​​the wall of the outer wall (including the gable wall). Public building area does not include any work