7 RESUMEN Los elementos estructurales horizontales (losas y cubiertas) de edificios son, por sus requisitos funcionales (geometría y diseño) y por su volumen ABSTRACT The horizontal structural elements (slabs and roofs) in buildings are, according to their functional requirements (geometry and design), and their volume; those which used large amount of materials for their constitution; being, at the same time, potential waste generators. The choice of a structural system is usually based on the ease of construction, area and room availability or economy; without considering their sustainable approach to waste generation. Comparisons and analyzes of four alternative elements used for slabs systems are presented in this paper, specifying the waste generated by construction and demolition, in order to define new criterion to be considered in their selection.