Church LeadworkPeter TJ Rumley
There are 16,000 parish churches in England, not to mention cathedrals, chapels and associated ecclesiastical buildings. The majority of these remarkable historic buildings incorporate some form of historic leadwork, whether it is decorative rainwater heads, downpipes or large areas of plain lead sheet that cover church spires and flèches, such as the one at All Saints’ Church, Shipdham, Norfolk, or the Great Lantern of Ely Cathedral. Lead’s chief characteristics are durability and malleability. The ease with which it can be melted, cast, jointed and decorated makes it suitable for a variety of architectural uses, not least on parish churches. Much of the UK’s historic leadwork has been lost through theft, and poor quality repair work has threatened the surviving stock. Clearly, every effort must be made to save what remains. HISTORICAL BACKGROUNDLead has been used since antiquity. The Romans used lead casting techniques to construct water pipes in several standard lengths and diameters, as recorded by Sextus Julius Frontinus, Water Commissioner of the City of Rome. In England, the Worshipful Company of Plumbers received its Ordinances in 1365 and was granted a royal charter by James I in 1611. Joseph Roberts, Royal Sergeant Plumber and Master of the Plumbers’ Company, was selected by Sir Christopher Wren to cover the dome of St Paul’s Cathedral in the finest Derbyshire lead. One only has to read HM Colvin’s, The History of the King’s Works, to realise the scale and variety of lead’s uses throughout the kingdom on historic buildings great and small. The dull silver-grey colour of lead has become so familiar that few people realise that many churches in the medieval period had whole roofs, domes, lanterns, and spires gilded, painted or tinned to provide a dazzling display of chevrons or chequered designs. John Stow’s Survey of London (1598) described the bell tower leadwork of the priory church of St John of Jerusalem, Clerkenwell, as ‘a most curious piece of workmanship, graven, gilt and enamelled to the great beautifying of the City, and passing all others I have seen’. Much of this decorative work was lost during the dissolution of the monasteries in the 1530s and 1540s when priory churches and cloister roofs were stripped of their lead. This was then recast and used during the conversion of ecclesiastical buildings into houses for favoured courtiers, as at Leez Priory, Essex, and Mottisford Abbey, Hampshire. After the dissolution, decorative leadwork was principally confined to the embellishment of country houses, such as the work carried out by Thomas Sackville at Knole and William Cecil at Hatfield. The skill of the plumber as decorative craftsman is abundantly evident here, in the richly delicate pierced work of rainwater heads, interlaced with crests, dates, heraldic arms, initials and complex tinned patterns of chequers, chevrons, strapwork and stars. As late as 1635 the patron of St John’s College, Oxford, Archbishop Laud, embellished Canterbury Quadrangle with highly decorative rainwater heads and painted pipes. This was, perhaps, the last important church commission which included decorative leadwork on such a large scale, albeit on a secular building. The Georgians also added leadwork to their churches, but this was much more reserved in execution, and it was not until the late 19th century that there was a resurgence of interest in decorative architectural leadwork. The revival was led by Arts & Crafts architects such as Philip Webb, and the writings of Ruskin, Morris and Lethaby. Visiting the best examples of this period provides a real, if fleeting, insight into the kind of decorations which would once have adorned so many of our country churches. In the few places where these important works of art survive, they must be protected. Lead within churches is not confined to the roof, gutters or downpipes. There is a fabulous rich artistic heritage of medieval lead fonts to be found in our parish churches, with many examples dating from the 12th century. Although few originals survive, these medieval treasures represent the largest and most complete group of medieval lead fittings in Britain. So too, lead coffins, lead water cisterns in churchyards, plaques, urns, statues and candlesticks, all of which are under threat and need to be protected and conserved. DEFECTS AND DETERIORATIONWhen exposed to the elements, lead readily reacts with water, oxygen and carbon dioxide in the air to form a stable, protective white surface film of lead carbonate. This film is the principal reason for lead’s longevity as a building material. However, where certain acids, such as acetic, formic and nitric acids, are present, corrosion may take place. Sources include bird droppings, lichen and rotting leaves, and the rainwater run-off from oak-shingle roofs also contains tannic acid: simply cleaning lead gutters and rainwater heads of leaves, moss and bird droppings will reduce corrosion. Being a soft material, lead is also vulnerable to mechanical damage. In the winter months, blocked lead pipes are vulnerable to frost. As the water in the pipes freezes it expands and splits the pipe; when the ice thaws the resulting damp can penetrate the interior of the church and cause further expensive damage. Lead downpipes should have their joints open at the collar to allow water to escape in the case of a blockage. This also makes it easy to identify which section of pipe needs unblocking.
The splitting and buckling of lead sheet is usually caused by thermal stress, as lead has three times the linear coefficient of thermal expansion of steel. The design must allow for lead to expand and contract freely. However, the material may stick to its support if there is too much weight in one particular section, or if the substrate deteriorates. The resistance can cause the sheet to tear. Too long a length will also result in excessive thermal expansion and contraction. Detailing is therefore critical. The Lead Sheet Association (LSA) provides specifications or ‘codes’ that define the standard sizes and thicknesses of lead sheet. The codes were originally based on the weight of a square foot of lead, so the higher the code the thicker the lead. (Code 6 lead sheet, for example, weighs approximately 6lbs/sq ft.) The LSA’s manual provides best-practice guidance for most common details (see Further Information below). Damage may also be caused by ladders placed against lead gutters and rainwater heads. Because lead is so heavy, insufficient support may cause the piece to fall. It is vital that leadwork fixings should be checked as part of a maintenance regime. CONSERVATION ISSUESThe basic principle of good architectural conservation is to preserve as much of the original fabric as possible by only undertaking work that is essential to a building’s survival. Where fabric has deteriorated, effective and honest repair should be the first consideration. Replacement is the last resort. Before survey or repair work is begun, a risk assessment should be carried out and approved. Access to leadwork at high level is gained via scaffolding, which affords a safe way to carry out the preliminary survey and any subsequent handling of heavy lead items. Fragile enrichments may become damaged when moved, so they should be placed in a wooden box and cushioned with bubble wrap. Very heavy pieces may need to be moved with a cradle and crane. As with all good conservation practice it is important to record, photograph and label the item. After a thorough examination, a written report should describe the piece, provide a location reference number and a conservation summary. All records should be kept on site as a permanent archive that may be referred to in future consultations. Choosing the right contractor to carry out the work is crucial. Indeed, a lead sheet contractor may not be qualified in dealing with decorative elements of church leadwork. Considerable damage has been inflicted on delicate and decorative leadwork through repairs carried out by operatives who lack sufficient understanding of historic fabrication and jointing methods, or who are unfamiliar with historic decorative surface techniques. All too often a piece of historic leadwork is replaced with cast iron or, worse still, plastic, by a contractor who does not know how to fabricate a repair section of lead pipe, undertake gilding, filigree work, decorative tinning or solder wipe jointing. In fact, decorative leadwork is relatively easily repaired, if you know how.
One technique used in historic repair work is solder wiping. In this dying art the method is to melt solder (tin and lead: prepared bars of solder are readily available) in a crucible and ladle the hot metal around the prepared joint with one hand, while using a moleskin cloth in the other hand to work the hot solder. The plumber exploited the fact that when tin is added to lead, the melting point drops proportionally and a joint may be made without melting the whole piece. Lead melts at 327.5°c – by adding one part tin to two parts lead the melting point drops to 227.2°c. Lead burning, on the other hand, is a more modern technique. A fine flame from an acetylene blow torch is used to melt the lead and fuse the two pieces together at the same temperature. This technique is not usually seen in decorative leadwork produced before 1900. It is possible to cut out a section of the defective lead and lead burn (or weld) in a new piece. Providing there is no restriction in the flow of water, misshapen rainwater heads and gutters do have a charm of their own and reshaping them to look like new can detract from this appeal. Lower level lead rainwater pipes may be subject to knocks and it may be possible to insert stainless steel pipes inside them to provide support or place protective grilles around the pipes. In areas where theft is likely, there may be no alternative but to replace the lower section with cast iron as a last resort. TRAININGIt is a national scandal that there are currently no formal, accredited courses in the UK that train plumbers in the conservation of decorative leadwork. Successive governments and the Sector Skills Council continue to ignore the pleas for funding from The Society for the Protection of Ancient Buildings (SPAB) and The Worshipful Company of Plumbers. An added confusion is that leadwork (sheet leadwork) has been moved into the ‘ConstructionSkills’ sector skills council (SSC) as it is seen as roofing rather than plumbing, which remains in the building services or ‘SummitSkills’ SSC. The senior plumbers who were trained in the traditional leadworking skills of solder wiped joints, soldering, pattern making and casting techniques are steadily retiring from the workforce. The technical colleges have thrown out traditional leadworking in favour of copper and plastic installation techniques, creating a growing craft skills shortage. Given this dwindling of expertise in the field of historic leadwork, it is all the more important that incumbents and churchwardens should be fully aware of the nature of the leadwork within their churches and have some notion of how it can be correctly preserved, repaired and protected. THEFT AND PROTECTIONThe cost of replacing stolen lead from churches is becoming prohibitive as the poorer parishes are unable to afford increased insurance premiums from the parish share. To add salt to the wound, insurance companies cap their payout in the event of a claim for stolen lead. In the case of one major insurer the payout is capped at £5,000 if SmartWater (a forensic marking liquid visible only under ultra-violet light) has been applied, and a paltry £2,500 if it hasn’t. There seems little point in being insured if £10,000 worth, or more, of lead is stolen. Clearly, churches have to be insured and SmartWater is a perfect solution provided the stolen lead is intercepted before smelting. However, this type of system has a limitation which tends to pass unmentioned: during the smelting process the unique chemical code is rendered difficult, if not impossible, to trace. In one recent case, a new lead roof installed to replace one that had been stolen was again stripped by thieves who even made use of the roofers’ scaffolding. The security system, in this instance, had not been switched on because birds had been setting off the exterior alarms upsetting the local residents. The alarm system in place was wholly inappropriate. State of the art security technology can now be used to alert incumbents and churchwardens on their home televisions, computers or even by mobile phone to the presence of an intruder in the church grounds, inside the church, or on the church roof. Alarms need not be set off unnecessarily with this type of system in place. With a web-connected CCTV system it is even possible to monitor the church visually in real time from anywhere in the world with internet access and to take the necessary action. This, combined with other security measures, such as SmartWater, will go some way towards addressing the theft of historic lead and protecting it for future generations.
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Historic Churches, 2009 AuthorPETER TJ RUMLEY MA DPhil FSA MIfA trained as an architectural historian and archaeologist. He is an authority on historic decorative leadwork and its conservation and is the author of the SPAB’s Information Sheet 15: Plumbing Leadwork: Joints and Pipes. he is also a regular consultant to both English Heritage and the National Trust. Further informationRELATED ARTICLES RELATED PRODUCTS AND SERVICES © Cathedral Communications Limited 2010
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