Sealants used on the exterior of the building envelope must fulfill their performance requirements in a very demanding location within the enclosure system, namely joints. For this reason they tend to be prone to premature failure if not properly matched to the surrounding conditions and materials. Sealant selection is a complex and time-consuming process involving the simultaneous consideration of a multitude of performance criteria. A systematic approach that enables a more comprehensive consideration of the various criteria is therefore important. The prototype expert systems are an attempt to do this. In this paper, a review is made of the main features of the initial prototype sealant selection expert system, including a brief discussion of the decision making process, the assumptions and inherent limitations of the system. Of particular interest in this paper is a description of the advanced prototype system being developed which provides significant improvements over the initial system. This advanced system will include an extensive database from which the following information can be extracted: weather data, sealant performance data, and graphic details database on sealant application.