A computer-implemented building design and modeling system and method are provided. In one embodiment, the system comprises a spatial database; means for defining a plurality of parametric objects, each of the parametric objects representing a construction component of at least a portion of a building being modeled and including an interface through which the parametric object communicates information with other ones of the parametric objects; a cost database containing, for each of parametric objects, cost information associated with the parametric object; means for assembling a model of the building utilizing the parametric objects, wherein each of the parametric objects is created in the spatial database; and means for generating in real-time a cost-estimate for the building model based on the cost information associated with the parametric objects as the parametric objects are created in the spatial database.