A knowledge-based expert system for preliminary design of mediumrise buildings has been implemented with the ability to generate building configurations. The system was developed on GEPSE, a microcomputer-based expert system development tool, which provides an environment in which predicated objects are separate from the rule bases. The inference mechanism utilises forward chaining and metalevel control. It has been shown that, based on the information taken from a user, the system generates a solution in terms of a list of proposed parameters. These parameters for preliminary design are suitable for future coupling to numerical analysis software for structural analysis and design. To further enhance the system capabilities, the knowledge base can be expanded for improved performance and graphics facilities can be incorporated for graphical manipulation and editing.