Buildings serve different purposes which are denoted as functions. Function of buildings is ensured by the application of adequate structural and formal means. Contemporary buildings are of complex nature, therefore, and consist of diverse components which play specific roles. Besides, some of them are crucial for a specific structural, functional or formal purpose while other play rather secondary role. Insulation is one of the most important building components. This is because it is accountable for proper protection of structural building components against negative influences of external and internal climate conditions. It also provides necessary means for occupational safety and comfortable building exploitation. Waterproof insulation belongs to one of the most accountable building components. It is mainly applied for the protection of a building interior against water inflow from the surrounding atmospheric and underground environment. It nevertheless can be also applied for different reasons e.g. for protecting partitions in wet compartments against getting wet. Diversity of waterproof insulation application purposes results in a considerable number of technical and technological insulation solutions. Such diversity makes the choice of the proper waterproof insulation a hard task. Moreover, the implementation of circular economy idea makes insulation choice even a more difficult problem. This is why the application of specialised approaches for supporting decision with this regard is welcome. A proposal for such approach is presented in the paper. The approach may benefit from the application of different decision support tools. A specific implementation of the approach is finally discussed. The implementation makes effective use of some renowned decision support tools. The comprehesive and universal nature of the proposed approach makes it also suitable for other specific purposes e.g. reliable bid selection.Keywords: sustainable materials and their production, decision support systems in construction, operational research, maintenance and renovation of buildings.