This report addresses the issue of developing an expert or knowledge-based system that deals with the problem of preventing the spread of fire between buildings. A knowledge-based program, EXPOSURE, has been developed that facilitates using more appropriate technology, expanding the problem domain, and providing cost- effective solutions. EXPOSURE can solve the problem of the prevention of the spread of fire between buildings for the case when the exposed building has combustible walls. The use of the expert system EXPOSURE and NFPA 80A produce significantly different recommended minimum separation between buildings. In some cases EXPOSURE calls for significantly greater separation and in others significantly less. In one case the separation required by NFPA 80A was more than five times greater than what EXPOSURE recommended. This program demonstrates that significant cost savings in achieving the desired level of fire safety and in assuring the levels of safety can be obtained by use of expert system fire codes.