Utilisation et technique de production du fer et du bois dans les charpentes de comble mosanes : premiers jalons d’une évolution du XIIe au XVIIIe siècle

The development of a comparative approach between the evaluation of the quantity of timber used in a roof frame and the volume of wood present in this same attic allows the acquisition of information about the economical, technical and social contexts in which a timber frame was drawn up. By carrying out this kind of comparison in a systematic way in twenty-tree religious mosan buildings (Belgium and Netherlands), it's possible to trace, step by step, thanks to dendrochronologic dating of the attics since 12th until 18 th century, the causes and consequences which influence the methods of constructions of the carpenters. In parallel, the confrontation of this result with the volumes of iron used in the attics reveals the growing importance of this material in function of the time and of the architectural principles. This part of the study was enriched by archeometallurgic analyses intended to identify the process of reduction employed to produce this metal with the aim to measure the possible influence of iron process innovations on the use of iron in the medieval and modern frames, knowing that Wallonia knew from the end of the Middle Ages the early development of the indirect iron process instead of the direct iron process