by Izaak Hudson RIBA AABC, Director, Dittrich Hudson Vasetti Architects
The repair of the east (presbytery) gable of Salisbury Cathedral has been a very interesting project completed admirably by the stonemasons, glaziers and carpentry teams of the Salisbury Cathedral Works Department as the penultimate phase of the Major Repair Project, a longstanding programme of repair of the exterior of the cathedral which commenced in 1986 with the Spire and Tower.
The Presbytery gable represents one of the earliest phases of construction in the cathedral and was completed by 1235. The surviving Chilmark stonework is predominantly medieval, although repairs were undertaken to the window shafts in the Nineteenth Century by George Gilbert Scott, and to the flanking pinnacles and windows in the Twentieth Century. The gable is at high-level and is flanked on all sides by side chapels and the Trinity (Lady) chapel, and is difficult to scaffold. The difficulty in scaffolding, combined with the lack of any recorded major repair works in the last 200 years, meant that the stone condition was found to be very poor when the gable stonework was inspected from close hand.
The Gable Stonework
In order to gain consent for what was going to be quite an intensive programme of repair and stone replacement to the large gable apex, three separate repair strategies and drawings were produced; Option A consisted of very minimal conservative repair (largely with lime mortar repairs); Option C was much more comprehensive stone replacement; with a middle-ground, Option B, of robust stone replacement for exposed and structural elements, with more conservative repair at lower levels. Each option was costed for masonry work but also for ongoing maintenance, including re-scaffolding at considerable height and thus cost, over the next 200 years. This helped the case for a more robust approach than the bare minimum conservation works. Demonstrating the long-term cost and intervention helped demonstrate the thinking behind the repair strategy to stakeholders and statutory consultees, and Option B was agreed as the most pragmatic solution. Preparing alternative repair strategies can be a helpful way of unlocking disagreements with statutory authorities on the level of stone repair, especially where time constraints mean that the authorities do not fully understand the condition of each stone or the rationale behind repairs. The approach of ‘showing your workings’ was appreciated by Historic England and helped with gaining their support for the work.
The South Pinnacle
The south pinnacle stonework had been previously patch-repaired in the past in Clipsham stone, much of which has been laid cutting through bed joints in an unsympathetic manner. Clipsham stone from Lincolnshire was used for repairs on the Cathedral immediately after the Second World War, when the Chilmark quarries and mines were still under requisition by the War Office, so it is assumed that these works were undertaken in the 1950s although no records relating to them exist in the Cathedral Archive. The pinnacle spire leaned considerably to the south and the spire rotated about a hinge point so that it rocked quite alarmingly. As the pinnacle spire stonework is hollow from below the top five courses, grouting or pinning would not have eliminated the hinge points. The condition of stonework to the pinnacle turret below the spire, particularly the lower eastern face, was so poor as to require quite high levels of localised replacement which could only be done by dismantling the pinnacle, as the required level of stone replacement would have heavily destabilised the pinnacle. Fortunately, the condition of the north (and more weather-sheltered) pinnacle was found to be much better.
The south pinnacle reconstruction involved some impressive setting-out drawings prepared in the drawing shop, and a number of clay maquettes of the base detail were made to ensure that water drained from behind the raised mouldings.
The South Buttress
The internal tracery of the south clerestory buttress abutting the gable had reached an advanced state of weathering, which was apparent to previous cathedral clerk of works in the 1980s. The tracery is self-supporting, and individual stones need to support the thrust of their neighbouring members. Some of the large tracery stones had deep cracks and missing chunks: their integrity was compromised and they needed full section stone replacement in places.
The Apex Cross
The repair of the apex cross was particularly well-executed by the cathedral masons; this required a new carved arm to replace a heavily cracked and delaminated section, as well as mortar repairs to the cross. The carved arm was dowelled in place and finished insitu.
Carvings
The repair works included the opportunity for new carvings where original stone carvings, particularly label stops, were so decayed that no original form or carving could be discerned. This meant that the cathedral stonemasons could hone their free-carving skills. In order to develop and agree the carving clay maquettes are made for discussion and refinement before being used as the model for stone. This especially helps to ensure water is not trapped in recesses, and particularly to ensure depth of carving provides light and shade so that edges can be discerned from distance. However, ultimately a lot of the carving is only visible from close-hand and can’t now been seen from the ground, but scaffold tours allowed access to the public and funders to see the carvings. They will undoubtably last our generation to be discovered by the team in future.
The Completed Project
Work also included conservation and new isothermal glazing to the 1781 window of Moses and the Brazen Serpent by James Pearson. This was a complex task due to the fragility and unique large enamel-painted crown glass panes of the window, and was admirably undertaken by the cathedral glazing shop, with new hardwood frames by the cathedral carpenter. The entire project took four years in total, alongside other repair areas and projects at the cathedral and non-cathedral commercial projects the Works Department undertake further afield.
