C O N T E X T 1 3 9 : M A Y 2 0 1 5 29 It was normal to use sheets 2 feet 8 inches wide by 5 feet 3 inches long.When welted over the rolls they gave a bay width of 2 feet 5 inches. The use of wood-core rolls was quite extensive in England in the first half of the 20th century. After the second world war a great many churches needed urgent repair after an extended period of building restrictions, rationing of materials and lack of funds. At Chichester Cathedral, West Sussex, the poor state of the lead roofs after the war meant that it was one of the first ecclesiastical buildings to receive repairs in 1949 after restrictions were lifted.At the time shortages of lead and its high salvage value meant that many churches were re-laid in copper. At Chichester the conical method was used with the standard sheet size described above.Whether or not it was a consideration in the choice of this method, its appearance to some degree mimics the use and spacing of wood rolls in lead-sheet roofing. Unfortunately, the conical method has had a number of shortcomings in this instance.With the exposed nature of the cathedral’s roof and open form of the roof attic, the wider bays used in this method are less able to withstand the wind forces pushing the sheets away from the roof slope. This has led to fatigue along the centre line of the sheets and horizontal welts. The interruption caused by the second world war had a significant impact on the development of copper roofing, with few new installations during the period of the war and the restrictions that followed after. Given the lack of skilled roofers, combined with further mechanisation in the production of copper sheet, the method of laying developed in new directions. In Europe developments looked to make use of the copper coils now being manufactured leading to the long-strip method, while in the USA there was interest in using thin gauges of copper to reduce cost. These two developments were brought together through a patent, registered by Albert Broderick, of prefabricated panels faced with metal.This method used thin-gauge copper sheet (half the thickness of a standard sheet), full-width cleats folded into dummy welts, and a thick substrate of fibreboard that provided strength to the thinner copper. The system was installed by Broderick Structures to a number of local authority buildings and residential blocks.The length of bays were formed off site with the dummy welts at the company’s compound in Woking.While the patent does not specify a sheet width, in practice it was largely formed from 27-inch-wide coils of 30 gauge (0.3mm) copper sheet. When fitted this formed two-foot-wide bays.The dummy welts were placed every 12 inches.The use of the Broderick system continued in slight variations in to the 1990s. I was recently invited to survey the roof of a recently listed modern church in the Diocese of Southwark.The church, St Paul’s, Newington, designed by HG Coulter of Woodroffe, Buchanan and Coulter, was completed in 1960. It was experimental in many respects, not least in its roof form. It has a prominent and unusual folded plate roof form. On the very steep roofs over the transepts and crossing the architect has used the traditional method with standing seams. Over the nave, where the folded plate form is most prominent, the architect has used a method of horizontally oriented sheets welted together in a manner more common on spires and domes.There are no vertical or standing seams, which would have affected its appearance. These examples illustrate some of the more developed and common alternatives to the traditional and longstrip methods. In addition to these there are more numerous experimental systems and batten forms that did not get widely disseminated. Some of these are chronicled by the Copper Development Association’s earlier reference books. The listed modern church of St Pauls, Newington, London. It was experimental in many respects, not least in its roof form. Jonathan Goode is an architect and director at Le Lay Architects.
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