This new Decision Support Structure (DSS) for architectural design assistance is a mechanism to share knowledge between design professionals for the purpose of improving decision-making. The approach is a unique implementation of decision-making theory and process mapping adapted to architectural design from more common use in the business and maufacturing domains. The new DSS is a software core for decision processing that easily links to Building Information Modeling (BIM) to extract the inputs for the DSS algorithms. The DSS is based on the World Wide Web making it accessible from anywhere. The DSS functions similar to a typical App with the seamless linkage to BIM and output that is easy to understand and print. This has not only practical value for reducing time for decision-making but may also mitigate potential litigation issues related to the decision-making process through improved documentation. The working prototype supports decision-making for green roof selection but can be expanded to a library of DSS for a wide range of decision-making issues for designers. The prototype has been tested by a sample of architects with very positive results.