This paper proposes a logic-based framework for representing and manipulating knowledge during Computer-Aided Architectural Design. The framework incorporates a meta-level architecture to represent declarative design knowledge and strategic knowledge used by the designer. It consists of an object layer, a design requirements layer and strategies for navigating through the design space. An extended first-order logic is described which has been used to represent some examples of architectural knowledge. This computational model is being implemented in KAUS (Knowledge Acquisition and Utilisation System), a general purpose knowledge-based system, founded in Multi-Layered Logic.