Building Westminster Hall: modelling the original roof structure

Before building, the architect needs certain facts about the site, the overall cost, the materials required and where they can be obtained. Hanmer’s Chronicle, neglected in plain sight for several centuries, provides answers to some of these questions. It records that timber for the roof of Westminster Hall came from Ireland’s extensive forests following negotiations in 1098 between William II (Rufus) and Murchard the High King.

The Westminster Hall roof had an estimated external span of 25m. Clearly William was unable to find timbers of the required dimensions in England. A reconstruction drawing has been completed based on the slightly later Romanesque roof frame of 16.8m external span at Ely Cathedral (1104-1140). About a century later, a further development of the gothic roof over St Hugh’s Choir at Lincoln Cathedral with a span of 14.21m saves timber by reducing the number of tie beams used to every third frame. This development was extended in 1292-93 by Margaret of Burgundy in building a hospital with a roof span of 21.10m using monoxylous timbers felled locally at Tonnerre (Yonne), of dimensions similar to those of Westminster Hall which may have been the model for her project.