During the restoration, several of the ancient roof timbers, including key rafters and a central purlin, had to be replaced.

timbers 是 timber 的复数形式。timber 指用于建筑的"木材、木料"，特指经过加工可用于建筑结构的木材。在建筑术语中常指屋顶或框架中的承重木构件。