26 BCD SPECIAL REPORT ON HISTORIC CHURCHES 32nd ANNUAL EDITION the prevailing wind direction, which requires the alteration of detailing to provide much higher levels of protection in newly exposed areas. The below ground drainage inspection report showed damaged or incomplete drains and soakaways resulting in damp and harm to the building. Repairs have been undertaken as part of the conservation project and future adaptation measures include increasing capacity of below ground drainage and slowing the flow of water either with planting or by introducing more permeable surfaces with proprietary ‘sustainable urban drainage systems’ (SUDs). Some sensitive relandscaping with the churchyard may manage the risk of surface water flooding and increase resilience, although further investigation and assessment of impact on significance and archaeology would be required. The amount of snowfall in absolute terms is small at the site presently and is predicted to decrease over time. Likewise, the rates of snowfall are also predicted to decrease over time, in-line with higher temperatures in the winter. The vulnerability to freeze-thaw mechanism of decay is therefore likely to reduce too, while wet/dry cycling of fabric saturation and high temperatures will increase, potentially leading to rapid decay. St Torney’s is affected by both extensive microbiological growth and pest activity including woodboring beetle. A key impact of climate change is the rising temperatures and prolonged warm weather, which create favourable conditions to promote microbiological growth and extend life and reproduction cycles of many pests. For many species the optimal temperature for growth and reproduction is between 18 and 24° C and RH above 60 per cent. The weather projections for this site indicate that it will be within the optimal range for a greater proportion of the year, significantly increasing the risk of decay through these mechanisms. Other interesting trends from the climate variables investigated at North Hill demonstrated changes to wind speed and direction. Shifting wind directions is particularly pronounced during the summer, with a majority of winds predicted to be from the north by 2080. These changes, when aligned with predicted higher wintertime precipitation levels, could indicate an increase in storm events. Globally, wind is one of the hardest variables to model and the size of this study did not allow further interrogation of regional and national data, but an overall change in wind direction has significant implications for building detailing. When planning for resilience it would be prudent to consider how existing details might respond to a change in prevailing winds. There is indication both in hydrological data for the surrounding site and in the UKCP projections, of a trend towards more extreme rainstorms. The elevated position does make St Torney vulnerable to storm damage and very high rainfall. The geotechnical assessment of the site indicated it was resilient to ground movement and is less likely to suffer heave or subsidence that would structurally impact the building. The presence of pyrite in the Tavy Formation, however, poses a potential risk to concrete and lime as it can oxidize and create acidic conditions when exposed to water and air. With wetter conditions and potential for localised flooding, these processes may accelerate, damaging the building. The significant changes in climate conditions for this site demonstrate increased maintenance, monitoring and preparation for potential loss of significant fabric are high priorities. New internal plaster, roof repairs and other repairs work undertaken as part of the vesting project help reduce the buildings immediate vulnerability, but the lifespan of these repairs can be expected to be reduced with failure and rapid decay. Loss of fabric, especially of the monuments, is already an issue and therefore a watching brief for particularly Extensive microbiological growth at St Torney’s The existing gutters are not expected to cope with predicted increases in rainfall and will be adapted were possible. Roof and parapet repairs being carried out at St Torney’s for the Churches Conservation Trust (All photos this page: Morwenna Slade) sensitive and significant elements of the building was advised to be a focus of the quinquennial inspections. MORWENNA SLADE MIRCS IHBC MSc is a leading conservation expert, visiting professor at UWE, SPAB Trustee and CIOB conservation advisory panel member. She provides consultancy for climate resilience, adaptation and energy efficiency to a wide range of organisations including HRP and HES. Morwenna Slade | LinkedIn
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