Knowledge informatics is still playing only a minor role in the design process of buildings and civil engineering efforts, particularly in the inception stage. The primary reason that most knowledge tools are not well integrated into the process is that most tend to be based on stand alone expert system technology. Improving the re-use of existing knowledge is required to increase industry performance. A solution could be a new generation of integrated knowledge systems. One problem that must be addressed is how to cope with the conflicting requirements of each particular subsystem when each is optimized for its own knowledge domain. No optimum solution exists that is able to simultaneously optimize each subsystem for a total solution. This paper discusses an approach to building knowledge integration that attempts to address these shortcomings through the use of combined product model and meta-knowledge approach.