28 C O N T E X T 1 3 9 : M A Y 2 0 1 5 method uses a standard sheet size comparable in metric dimensions: 600mm by 1800mm and 0.6mm thick. The ability to manufacture long coils of copper sheet led to the development of new roofing techniques. In the 1950s the Swiss long-strip method was developed. The need for horizontal welts was avoided by reducing the distance between standing seams. This allowed long continuous vertical sheets to be used, allowing the copper to be laid more quickly.The long-strip method, now the predominate form of new copper sheet roofing, is often used when replacing roofs previously covered in the traditional method. Alternative methods of copper roofing were developed throughout the 20th century to improve economy and ease of fitting by using new manufacturing processes. Many historic listed buildings survive with these rarer methods of copper roofing.Without understanding the variety that can be encountered and the performance (or defects) that they can exhibit, there is a danger that this construction heritage will be lost under the standardisation of current replacement specifications. One of the more ornate methods of copper roofing, using pressed metal tiles, was developed in the 19th century and used mainly on the continent. It departs from the standard practice of interlocking sheets by using individual tiles or shingles in a manner similar to conventional tiling techniques.The shape and size of tiles can vary.The fish-scale tile, one of the most commonly used shapes, produces an interlocking appearance. It can be used on curved roof forms, as seen at the Western Pumping Station. Copper tiles were seemingly used for their decorative appearance, while costing more and providing a potentially lesser standard of weathering. Other considerations might have been that they were easier to fix and to make repairs to small areas of damage. Early pressed tiles appear to have been introduced from the continent in the 19th century through the import to England of material by European manufacturers. Today tiles are still manufactured in Bray, France, by VMZinc, principally for the continental market. Tiles are often used in combination with more decorative hand-formed elements to ornament the hips, ridges and eaves of more prestigious buildings. Examples of this elaborate metal-smithing can be seen in London along the roofline of Regent Street. I was fortunate to visit the factory in Bray and saw first-hand the skilled work involved in putting together these ornaments. With the development of thin sheets of a consistent thickness, a system of vertical joints was developed, using wood core rolls and battens. The use of wood core simplified the fitting of the sheets and provided added protection from trampling of standing seams on near flat roofs. It is suggested in publications by the Copper Development Association that these earlier square battens with a capping strip developed into a triangular profile with a rounded top so that adjacent sheets could be welted directly together.These are known as conical rolls.The copper sheet used with conical rolls was a different size to the traditional method, so that the distance between rolls could be increased for economy. 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. A conical roll
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