Historic Churches 2021

12 BCD SPECIAL REPORT ON HISTORIC CHURCHES 28 TH ANNUAL EDITION concern I had over the condition of the fabric, I concluded that the most appropriate method of protecting it was to re-render the chancel. The Church Commissioners supported this proposition and in 2020 we did just that, limewashing all the window masonry and weatherings at the same time. Even the masonry to the late 19th- century east window was showing signs of decay, and I saw no reason not to protect it and prevent the inevitable piecing in of stone indents in years to come. Why has it become the norm to appreciate stones covered in lichen and other micro- biological growth when they are leaching acids causing slow but inexorable decay? THE BENEFITS OF RENDER As for the technical benefits, some may ask whether rendering a wall is significantly better than simply repointing it? Well, apart from covering over the more vulnerable stones (arresting their decay and avoiding the need for endless cycles of indent repairs and shelter coating), render does have a significant benefit over simply pointing, which is that a rendered wall will dry out much more quickly than one that isn’t rendered. Not only will render cover all those inherent cavities but it will also cover miles of interfaces between masonry units and mortar, and water traps, that are vulnerable to water penetration. Pointing a rubble wall which was clearly originally rendered places an unrealistic onus on the skill of the mason, and I think a medieval mason would be laughing at that prospect. A well-made traditional hot lime render will also act as a poultice, with a pore structure perfectly facilitating the movement of water molecules towards the evaporation front of the external face. Limewashes, being pure calcium carbonate with no aggregate, naturally take this further. If you think about it, masonry units and most forms of aggregate impede the movement of water, so the less aggregate you have as you approach the outside then the easier water can move through it (same for the internal plasters). Of course, by the same token, when it is pouring with rain, such a material will readily soak it up, but it will soon reach saturation and shed water down the face of the wall. Research has shown that a solid masonry wall in good repair will not be saturated beyond about 100mm from its surface. So, by reinstating the original render we are pulling the moisture out of the walls by the most effective and efficient means possible. This eliminates the decay of rubble stonework and provides a drier wall. That in turn reduces the strain on internal lime plasters and fittings, and by extension creates a drier internal environment. In addition, removing the drying surface to the face of a render means that the damaging effect of salts is moved to the sacrificial face of the lime render rather than the poor stones found in rubble walls such as clunch, lias and hybrid stones². As a result of our penchant for ‘pleasing decay’ the fabric of our churches has been greatly compromised, I believe, leading to an accelerated rate of decay over the last 150 years or so; somewhat ironic when we think of the Victorians as the great restorers. In doing so they have unwittingly created the perfect eco-fridge – cold saturated fabric cooling the interior – everything we have come to expect of a church. Fortunately, in recent years, developments in the lime revival support the view not only of the historical prevalence of finishes, but also how they actually function. Many practitioners who have extensively researched this area have found how important and integral lime finishes actually are. In Scotland and the north of England they have already began to implement this. Stirling Castle, for example, was fully limewashed some 20 years ago, and south of the border, Historic England’s Damp Tower research came to the same conclusion – its findings pertinent not just to church towers. I would suggest that it is a much better proposition to have a maintenance regime of limewashing than to have a costly programme of masonry repairs every few years. Hopefully this will be borne out by what we have recently carried out at West Wratting, and West Dereham. I admit this is a complete change of look, but one which I think is beautiful in its own way, and lets everyone know that the church community is alive and well. To summarise, we need to seriously reappraise our feelings about what a church is expected to look like, and remember that at its most basic level architecture needs to provide shelter. It is not good enough to accept that our churches are cold and damp if we are to expect them to have a sustainable use beyond the occasional service. We have to give them back their coats to wear. References ¹ Tim Meek and Paul Adderley, ‘Harl- as-you-go! Integration of mortars and the implications for robustness and longevity in an exposed environment’, The Journal of the Building Limes Forum , vol 26, 2019 ² David Wiggins, ‘Traditional lime mortars and masonry preservation’, The Journal of the Building Limes Forum , vol 24, 2017 ASHLEY COURTNEY is a conservation accredited architect based in Cambridge with over 20 years' experience. He looks after some 40 churches with projects ranging from repairs to re-orderings – see www. ashleycourtney.co.uk . The west wall of the nave at Upwell St Peter before and shortly after rendering: the masonry was never designed to be exposed and the protection provided by the render coat is essential.