Green roofs have become a sustainable construction building system that offers interesting environmental advantages over traditional roofing solutions. However green roofs design is still based on conventional materials. This article begins a research which considers both the study of the functional benefits of green roofs but also the goodness of their own construction. Specifically in this paper the possibility of using rubber crumbs as drainage layer in green roofs instead of the porous stone materials currently used in some commercial solutions (such as expanded clay, pumice, natural puzolana, etc) is suggested. This solution would reduce the consumption of these natural materials, which also require large amounts of energy in their transformation process. Moreover it would provide a solution to the problem of waste tires. Since the purpose of the drainage layer is the optimum balance between air and water in the green roof system, first the ability for draining of rubber crumbs was studied and was compared with that offered by stone materials. The new solution using rubber crumbs is also studied, with experimental trays, to test if it would keep the same insulation properties that the green roof with stone materials. Early results obtained in the experimental trays show that rubber crumbs are a good substitute for stone materials used as drainage layer.