||Classification is an important issue in building construction. In this paper, it is assumed that building design is performed by modelling and that computer based building models are used as the basis of data exchange. Therefore, the primary focus of the paper is classification in connection with modelling and how classifications can support this. A major issue in modelling is the initial identification and definition of model objects. Subsequently, it is assumed that the objects will persist and that they are further detailed. Instead of classifying building elements by function, it is proposed to classify functions and link building component types/classes to function nodes. When a model component is created, a primary function can be attached to the component and a component type can be selected. Each time a function is attached to an object, the defined attributes can also be attached and, when a component type is selected, values of attributes can be assigned.