ABSTRACT
The preservation of historic timber roof structures and the recognition of their heritage value require a thorough understanding of their structural behaviour. In Belgium, this is particularly true for 19th- and early 20th-century timber roof trusses which are still under-recognized and under-researched compared to more ancient timber frames or 19th-century iron construction. The chapter aims to trace back the design methods available to Belgian engineers for the construction of timber roof structures between 1840 and 1914. It demonstrates how iron engineering has inspired and speeded up the transition from traditional carpentry to timber engineering. In France and Germany, Stefan M. Holzer traced back the introduction of the new design methods in roof construction through the example of the mixed timber-iron Polonceau roof, which rapidly became an all-iron structure by the end of the 1840s. Fom the mid-19th century onwards, once innovative calculation methods had been established for iron construction, the latter were simply applied as such to timber trusses.
