44 C O N T E X T 1 3 4 : M A Y 2 0 1 4 IAN WEIR Timber repairs at Scarisbrick Hall A scheme to replace areas of defective lead roof led to an extensive programme of timber repairs after investigations revealed potentially disastrous damage to the structure. Scarisbrick Hall is a Grade I listed country house in Scarisbrick, Lancashire. Most recently the building as a whole has been occupied and used as a private school.The AWN Pugin-designed Great Hall was part of a complex of buildings built forThomas Scarisbrick, begun in 1814 to replace the 16th-century seat of the Scarisbrick family. At the centre of the composition is Pugin’s two-storey open hall with a steeply pitched roof and a three-stage lantern at the ridge.The interior of the hall is richly embellished with timber panels, very ornate timber carvings, cornice mouldings, heraldic decoration and other timber features. What started as a scheme to replace areas of defective lead flat roof (as part of a planned maintenance regime to stop the increasing water entry and risk of damage to the ornate ceiling) revealed other more significant damage to the adjacent structure. The need to replace the lead roof covering was identified as part of the management plan.The area was surveyed, and the condition of both the lead covering and the supporting timber were known to be generally poor, and in some areas adversely affected by wet rot. The planned repair to the roof was approved and grant funding was provided by English Heritage. The work began on site in January 2013. Access scaffolding and a temporary scaffold roof had been erected over the work area. The removal of the defective lead sheet covering was progressing as planned. The timber boarding and roof joists had been inspected. Their isolated decay due to water penetration was as predicted, and within the contingency and provisional sums contained within the contract. The lead sheeting was found to extend beyond the flat roof gutter as a lead soaker and flashing dressed up the slope of the adjacent Great Hall roof. Investigations revealed the lead to be continuous. Removal of isolated stone roof slabs and lifting of the lead revealed the bearing ends of the main timber trusses and the wall plate supported by the main wall to the hall. It was at this location that the full impact of the water penetration was revealed. Water penetrating the failed lead had migrated towards the supporting masonry on which and into which the Great Hall timbers were constructed. Decay was visible in the flat roof deck, the gutter timbers, the embedded wall plate, the roof joist bearings and the ends of the seven primary truss rafters that were sat on to the wall plate. We identified that the decay had penetrated the heart (sap wood) of the large timber members and had travelled up the length of the members to varying degrees. The wall plate in parts had been crushed under the load from the trusses and some of the ends of the rafters had been crushed due to the decay. Not all of the timber structure could be easily seen or determined from above, so an access scaffold tower was erected internally to inspect a selection of the timbers from below. This revealed that water had penetrated in some areas to an even lower level than the wall plate, leading to the deterioration of some of the intricate carpentry mouldings, panels and Pugin’s Great Hall, with its steeply pitched roof and three-stage lantern, stands at the centre of the composition. Access scaffolding and a temporary scaffold roof was erected over the work area.
RkJQdWJsaXNoZXIy MjgyMjA=