The development of a new comparative approach establishing a link between the evaluation of the quantity of barks used in a roof frame and the volume of wood present in this same attic allows the acquisition of essential information for the apprehension of the economical, the technical and the social contexts in which a timber frame was drawn up. By carrying out this kind of comparison in a systematic way in about thirty attics of religious buildings dispersed in the Walloon region (Belgium), the evolution of these contexts develops step by step since 12th until 18thcentury and highlights phenomena which influence the methods of constructions of the carpenters, like the appearance of the saw or the rarefaction of the forest resources. The confrontation of this result with the evolution of the volume of iron considered in the attics reveals the catch of importance of this material in function of the time and of the architectural principles. Iron appears in the roof frames of our areas in the same time that the advent of the Gothic architecture in link with the increase of the roof’s dimensions. Its employment generalizes then knows a real expansion at the 17th century because of the rarefaction of the forest resources but also because the preindustrial techniques allow it. ; Le développement d’une nouvelle approche comparative, établissant un rapport entre l’évaluation de la quantité de grumes mises en œuvre dans une charpente de comble et le volume de bois effectivement présent dans ce même comble, permet l’acquisition d’informations essentielles à l’appréhension des contextes économique, technique et social dans lequel une charpente a été dressée. En réalisant ce type de comparaison de façon systématique dans une trentaine de combles d’édifices religieux dispersés dans la région wallonne (Belgique), l’évolution de ces contextes est tracée étape par étape du XIIe au XVIIIe siècle et met en exergue des phénomènes qui influencent les modes de construction des charpentiers, tel l’apparition de la scie ou la ...