16 BCD SPECIAL REPORT ON HISTORIC CHURCHES 31st ANNUAL EDITION further issues. Therefore, removing stone is always done with an eye on the future integrity of the building. Stone tends to be most badly damaged when there is repeated wetting and drying, causing cycles of crystallisation. This tends to happen where water is able to pool, where weathering details have not been maintained, and where drains and gutters are blocked. Standing water saturates the masonry, washing out the matrix of the material and dissolving salts. These then appear on the faces of the stones as efflorescence; surface crystallisation of the salts. Less soluble salts may crystallise within the pores of the stone and start to break apart the material. This is called cryptoflorescence and it causes powdering and blistering of stonework. Once the matrix of the stone is shot and the stone is friable, there is good reason to replace, repair or consolidate the stone. The decision-making concerning these areas of conservation are best worked out with the long-term preservation of the building in mind and with professional and experienced input. To prevent areas from getting into such a state, it is best to work out a conservation strategy that includes the management and maintenance of water shedding detail. ROPE ACCESS Rope access, carried out by qualified stonemason conservators, enables heritage specialists to rapidly respond to emergencies, as well as providing a cost-effective response to the everyday effects of our weather. Take a piece of detailed carving such as a grotesque or gargoyle, whose features have been lost over the decades as an example. Using rope access techniques, a qualified stonemason can remove damaged stone safely and neatly, ensuring that the fabric remains weathertight, without the need to install a scaffold. Using the latest technology, templates can then be made and new stone cut (after being sensitively sourced) before carving provides the exquisite final details. The new masonry can then be installed either by rope access or, if justified by the scale of the work, from a scaffold. To use rope access safely and effectively, the Industrial Rope Access Trading Association (IRATA) has developed three levels of training, the highest being Level 3. Stonemasons working at height should be qualified to Level 3 or be accompanied by an IRATA Level 3 rope access technician. Rope access was used in both the scenarios mentioned above where pinnacle failure occurred. In the first case it was utilised to haul the 15 stones out of the vaulting and down to safety on the ground where they could be measured up and carved anew. In the second case rope access was used to remove the teetering pinnacle so it could be conserved and re-fixed at a later date. Rope access can also be used by qualified stonemasons to regularly inspect areas that may be prone to storm damage. Rope access not only allows for cost-effective annual, biennial or triennial access to the areas but also enables conservators to document, measure, handle and repair materials in situ. Inspections of fragile stonework at height via rope access makes it more cost-effective to keep an eye on pinnacles, spires, lanterns, turrets and towers, metal detailing, glazing and leadworks, and the all-important details which manage the effects of the weather; drainage details and weatherings, including gargoyles, leadworks and such like. COMBINING SURVEY INSPECTIONS WITH REPAIRS In the past few years, where the British weather seems to have become more extreme, be it from rainfall, storms or hot sunshine, the stones that have the most exposure are suffering. Often stones that we might expect to have a metal fixing do not, while others contain metalwork that is subject to rust, causing spalling and damage to the surrounding stones. Sometimes detailing has been overlooked in the past in search of a temporary solution. Joints may have been changed, or indents made that cannot be expected to last hundreds of years, meaning these details need inspecting. In the rare cases where stone fall occurs, whether toppled by wind gusts or the moving of leadwork, hazardous material needs to be removed within a carefully managed system. All evidence should be documented to maintain continuity of the historical record, and educated conservation or replacement recommendations should be presented before works are carried out. As well as the nature of the structures, it is as important to understand the current condition of the given material: stone, which might be original or renewed, blistering, spalling, delaminating or structurally cracking; leadwork; other metalwork such as pins, copperwork and meshes; woodwork such as structural timbers or crosses. All need to be included within a detailed report on the structure as a whole. A conclusion to the problem should be sought, with recommendations for a solution, and then a plan of action created with further steps. Fingertip surveys of areas at height result in comprehensive and detailed reporting on the condition of weathering details such as spires, hooded arches, string courses, pinnacles, gargoyles and coping stones. Giving a stonemason up-close access to the stone for taptesting and a hands-on examination allows them to not only assess defects, but repair, recarve and replace stone detail. Rope access also facilitates regular repointing, for example on vertical joints within cornices, string courses, spire stones and other weatherings that get washed-out over years of exposure. Each inspection comes with a report carrying recommendations that are graded in terms of priority for the building. Priority works may only be small phases of conservation repair but to carry them out on local areas of the building can save large amounts of damage in the future. Bespoke, localised repairs, without the use of a scaffold, tend to be able to fit within budgets and events. Rope access is non-intrusive, where scaffolding might be, so it allows bespoke, localist conservation repair works to go ahead without hugely interrupting the day-to-day use of the building. It enables the stonemason to manage, consolidate and mason fragile, pinnacle stonework. Techniques and cost-efficient methodologies are in a constant state of development, either using rope access, mobile platforms, scaffolding or combinations to both remove and replace stone detail. These techniques and methodologies also embrace high-level lead work. The detailing of lead work tends to penetrate the stone, for example with flashings or lead drainage through a stone parapet. These crafts have developed alongside one another. Installing new lead overflows allows the upkeep of any drainage systems and lead weathering currently experiencing a lot of use due to the extreme weather. When small phases of works are surveyed, documented and carried out with this ‘little and often’ approach, by specialist stonemasons and leadworkers, it becomes far more a cost-effective in the long run. RICHARD MARTIN is Director of Heritage Stone Access Ltd (www.heritagestoneaccess. co.uk), a stone carver and rope access technician.
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