Architectural Design is a technological field where the use of Information Technologies are lagging behind the current state of the art of other human activities. Although CAD and related tools have been of invaluable interest, they are intended for drawing (first generation) and construction (second generation). Even recent developments of the 2nd, like BIM/IFC and others, are not directed to the creative work of the architect, dealing with such things as spaces, human needs or functions. ONTOARCHI project is a large framework of research efforts, trying a new path to develop o new paradigm in automation of Architectural Design. The core concept of the project is the natural association of a logical descriptive language (ontologies - OWL language in Protègé development environment) populated with architectural theories and/or methodologies and a set of operational languages reasoning over those defined ontologies. Those operational languages respond to the input of design requirements, querying the ontologies, and outputting the definitions of the likely and optimized projects that are as close as possible to the desired requirements and the most useful for the future commanding architect's work. This paper describes only one of the lines of R&D of the project. Its goal is to provide the architect with automated drafts and schemes of the sizes, shapes, distribution, interfaces and borders of the building spaces. It assumes that the most influential determinant of form is the set of human activities unfolding in the edifice. The created ontology encapsulates theories on relations between activities and spatial form. As this is a centennial field of interest of architectural studies, the ontology and its population could be defined heuristically, with an effort of logical formalization of a very extensive bibliography. The main concepts of the ontology deal with typified people, human activities, spatial requirements, equipment, environmental requirements, and construction elements. For now, the current outputs are schemes with the size of the spaces, their relative positioning considering attraction and repulsion factors, the material requirements of their mutual interfaces and with the exterior.