CEN/TS 19103 gives general design rules for timber-concrete composite structures. (2) It provides requirements for materials, design parameters, connections, detailing and execution for timber-concrete composite structures. Recommendations for environmental parameters (temperature and moisture content), design methods and test methods are given in the Annexes. (3) It includes rules common to many types of timber-concrete composite, but does not include details for the design of glued timber-concrete composites, nor for bridges. NOTE For the design of glued timber-concrete composites or bridges alternative references are available. (4) It covers the design of timber-concrete composite structures in both quasi-constant and variable environmental conditions. For ease of use, it provides simple design rules for quasi-constant environmental conditions and more complex rules for variable environmental conditions. 1.2 Assumptions (1) The general assumptions of EN 1990 apply. (2) CEN/TS 19103 is intended to be used in conjunction with EN 1990, EN 1991 (all parts), EN 1992 (all parts), EN 1994 (all parts), EN 1995 (all parts), EN 1998 (all parts) when timber structures are built in seismic regions, and ENs for construction products relevant to timber structures.