The present paper aims to show on possible interpretations of the medieval construction process of the chapter house at the Sénanque abbey. Describing the irregularities found in this chapter house, and then analyzing them to consider their reasons, the authors tend to give rational and coherent explanations to these irregularities. To achieve this goal, a metrological analysis concerning the medieval measures will be introduced in this paper. Principally caused by the change of the initial plan of the chapter house, these irregularities also explain well the compromising attitude corresponding to each construction step already finished.
