One of important problems in multi-storey housing is that building systems can not meet variability demands of users. In this study, organization of building approach which can be applied as a strategy in order to set a suitable environment for meeting variability demands will be explained. The term the hierarchical organization of building elements explains a building system order in which building are interactive sub-systems within framework of hierarchical order. A house building system, which has building within framework of hierarchical order can supply change possibility in housing by means of changing of elements(sub-systems) in sub-levels of hierarchy. For a hierarchical system to be a variable model (open system), its sub-systems must be independent from physical and functional concerns. In addition, in hierarchical building systems, separation of fixed and variable parts must be realized and, of these parts must be defined. In variability aimed Open Building works, building is generally formed of three main sub-levels which are called Tissue, Support and Infill. Each of this levels has different variability capacity and decision levels within framework of hierarchical order. In order to achieve an increase in variability of multi-storey buildings, in this study, building system is divided into two parts with permanent and changeable properties within framework of hierarchical order. In this dividing, parts with fixed and permanent are called and part with variable is called construction. The fixed and bearing support construction part offers capacities for variability and assigns change circumstances. The non load-bearing infill construction part which can be changed easily meets variability and re-use needs of users.