by Elgan Jones
We were kindly invited to join Patrick Duerden, Aliza Ross and Henry Sanders (SPAB Scholar 2012) of Donald Insall Associates on their site inspection of Westminster Hall. It is such a rare opportunity to view and inspect the fantastic 14th century roof timbers up close, which at the time boasted the widest span of any timber truss in Europe. We were also joined by carpenter and timber framer Tom Massey (SPAB Fellow 2014), his father Peter Massey, and structural engineer Robert Bowles.
After a quick frisk through the airport-style security, we stepped into the main hall and gazed in awe at the vast, clear space. Not a single column obstructed our view.
Donald Insall Associates were overseeing the cleaning, conservation and repairs of the interior masonry walls, which date from the 14th to the early 20th centuries, and roof timbers. Patrick explained some of the logistical constraints of working in the hall, such as the scaffold which, if required, could be taken down and removed in six hours. This partly explained why the works were phased and confined to a few bays at any one time.
Patrick also explained about some of the challenges they experienced in cleaning and conserving the Reigate stone, it is susceptible to decay on exposure to the atmosphere. Sir Christopher Wren once said: “that which is to be most lamented, is the unhappy Choice of Materials”. The performance and quality of Reigate stone can vary greatly depending upon its original bed depth and source. Cleaning methods which could introduce further moisture into the stone were avoided to prevent damaging the stone further. Instead, cleaning systems such a brushing and pyrex latex cleaning were used.
A combination of poulticing and Nano-lime technology was used for conserving the detailed figures within the frieze. Sections of the frieze were conserved using shelter coat and, in order to avoid the uniform flat colour which can often catch the eye, a two coat system was used. Interestingly, the colour of the base and top coat were slightly different so that the top coat could be slightly brushed back revealing the colour of the base coat.
In areas where the decayed friable stone posed a risk to visitors below, the approach was to replace it with Chicksgrove limestone, a more durable stone which aesthetically was a close best match to the Reigate. The profile of the new stone was cut to match the original form and not the current weathered face.
The project also included the cleaning and conservation of the 14th century roof timbers and installation of a new lighting scheme to improve the overall presentation of the Hall.
The great mystery of the Hall is the form of its original roof. Not until the 13th or 14th century could carpenters create roofs significantly wider than the length of the available timber, and so it was assumed that a single or double row of columns was needed to support the Hall’s roof. However, recent archaeological explorations suggest these theories have no foundation and that the roof may have been self-supporting from the beginning.
Initially the roof timbers will be vacuum cleaned to remove the build-up of dirt and dust before a closer inspection to examine and prepare a schedule of repair is undertaken. As the scaffold had not long been erected this work had not yet been undertaken however it did give us an opportunity to view the detail and construction techniques of the hammer beam trusses and how the later concealed reinforced steelwork introduced, by Frank Baines in 1914-23, integrated with the historic timbers.