Construction of the nave was underway from around 1115, and roof timbers dating to 1120 suggest that at least the eastern portion of the nave roof was in place by then. The great length of the nave required that it was tackled in phases and after completing four bays, sufficient to securely buttress the crossing tower and transepts, there was a planned pause in construction. By 1140 the nave had been completed together with the western transepts and west tower up to triforium level, in the fairly plain early Romanesque style of the earlier work. Another pause now occurred, for over 30 years, and when it resumed, the new mason found ways to integrate the earlier architectural elements with the new ideas and richer decorations of early Gothic.