The durability of a building construction material is defined as "the ability of a product to maintain its required performance over a given or long time, under the influence of foreseeable actions." Therefore, depending on the intended use of the product and its service conditions, the durability can be a serious problem from both a technological and economic point of view. Also discussed in this book is an experimental analysis of the behaviour of timber-framed walls used as main bearing capacity elements in the construction of prefabricated timber structures. The design of energy efficient buildings; and the characterization of advanced structural materials by acoustic emission indices is also examined.