This document identifies the requirements, the basic performance criteria and evaluation of conformity for precast ribbed elements made of reinforced or prestressed normal weight concrete, used in floors or roofs. The elements consist of a top slab and one or more (usually two) ribs, containing the main longitudinal reinforcement; a bottom slab and transverse ribs may also be present. Some examples of precast elements considered in this document are shown in the Informative Annex A. This document covers terminology, performance criteria, tolerances, relevant physical properties, test methods and aspects of transport and erection. This document does not cover load bearing capacity determined by testing.