Architects face nowadays the challenge of raising buildings edifices matching functionality of structural design, sustainable raw materials, thrifty energy consumption and aesthetic integration within surrounding environment influenced by human culture and civil engineering heritage considerations. They often specify wood for various reasons: cost, ecological issues, design versatility, construction facilities, etc. To improve timber structures, material engineers develop innovative wood products allowing to overcome dimensional and mechanical limits imposed by trees with e.g. longer span capabilities, higher dimensional stability, or higher strength to weight ratio. In all these aspects, the question of life expectancy of wood based materials and timber structures is of major importance for building safety and one of the major obstacle in people's mind for investment. Wood material achievements have to be designed with an expected long term viability that englobes several topics such as detailing construction considerations or even durability issues of termites and fungi resistance as well as aesthetic issues on colour changes in wood due to weathering – but, as a first step, the longevity of wood inherent mechanical performance.