Two Churches, One Forest? Timber Supply for the Holy Cross Collegiate Church and St. Paul Cathedral’s Roof Frames (1251–1351 CE)

The churches of Saint-Paul and the Holy Cross in Liège represent two important examples of medieval architecture within the Mosan region. Both have been the subject of numerous historical, archaeological, and dendrochronological studies and publications. The oak (Quercus sp.) frames of these two buildings have been dated to the 13th and 14th centuries, with relatively comparable felling phases. The comparison also extends to their construction typology and progress, suggesting that the same school of carpentry may have been responsible for both Gothic structures. Given the similarity of the construction typology and dating of these church frameworks, what can be said about the supply of wood required for both frameworks? Therefore, the analysis of tree-ring series, known as dendrochronology, contained in preserved timbers is relevant. To answer this question, we first applied a sampling protocol to (1) ensure the comparability of the two corpora and (2) assess the correlation thresholds between the annual ring series. A total of 162 timbers, dated and documented through 273 radii, revealed a new construction phase occurring between the mid-13th and mid-14th centuries. The hierarchical classification of individuals demonstrated strong correlations during tree felling in the mid-13th century, whereas correlations decreased in the subsequent phases. These findings indicate a close proximity among the forests that supplied the first felling sites. Conversely, subsequent felling suggests that the builders were sourcing resources from different forests, probably further apart.