Centuries of exposure to the weather and the loss of the spandrels to the clerestory windows had left the soft sandstone voussior stones particularly exposed. Although an attempt had been made in the past to protect these less durable areas of masonry with lead cloaking this had proven unsuccessful. As such, rain water was becoming trapped preventing the masonry from properly drying out and causing further erosion and damage from freeze/thaw action.
The original aim of the project was to slow the decay to the fabric with minimal masonry conservation, however the extent of the severe erosion and displacement of several of the voussiors and sections of the western mullion required this to be reconsidered. It was therefore decided that it would be best to rebuild and reset these areas with minimal new stonework, as these would otherwise fail, causing a significant health and safety risk to visitors and a significant loss to the readability and understanding of the highly important site.
Great care was taken to conserve as much original masonry as possible, removing vegetation, descaling in areas where there was an imminent risk of failing masonry, and re-pointing with specialist lime mortar. The lead cloaking was removed from the arches, and small areas dismantled. Following extensive analysis and research of the original forms of the mullions and arches, new hand carved masonry was then produced at Recclesia’s purpose-built masonry workshops, using stone sourced to match the existing masonry in composition and appearance. These new sections were then sensitively constructed ensuring the form and setting out of the original conserved masonry was maintained.