Significant criteria for choosing materials (consolidants and protective coatings) for the conservation of the built cultural heritage were gathered from the literature and by consultation with experts working on the preservation of cultural heritage. Ten criteria were chosen from these, and a questionnaire was prepared and sent to stakeholders in the cultural heritage conservation domain in order to evaluate, score and rank the importance of the proposed criteria. Based on the results obtained a decision support tool was developed, aimed at conservators and other stakeholders, to help them to make sustainable decisions with regard to the selection of conservation materials for treatment of the built cultural heritage. Performance characteristics and health and safety were identified to be the most important criteria. A preliminary decision can be made based on these two criteria, however, reversibility, minimum intervention and re-treatability are also of very high importance and additional information about these characteristics of the material are required to support decisions. Information about environmental performance, peer recommendation, the application techniques, the price and availability of the materials, which are also integrated in decision support tools, can help conservators and stakeholders to reach a final decision on interventions. The study also provides feedback for the manufacturers of conservation materials. For the users of material, it is very important that the manufacturers clearly identify key characteristics (i.e. criteria) on the product, including those related with environmental performance of the materials.