Elphin Watkin asks for a rehabilitation of a traditional natural roofing material SHINGLESIN BRITAIN: A DISEASEORA ROOF COVERING? determine if these were from another roof, as at Marlborough, or were considered suitable for re-use. The continued use of shingles, over the centuries, has been mainly confined co church spires as the reduced weight, and cost, over the most common alternative (lead) are still considered co be advantageous. WHAT IS A SHINGLE? A shingle is a wooden roof tile of similar size to its clay variant, and riven or sawn from good quality timber. The most common early material was oak, but since the 19th century there has been steady change co imported cedar from North America. These can be up to 15 inches square. The ideal shingle, regardless of the timber used, comes from a good straight grained unstressed tree with an even ring growth. This high-quality timber is usually found in the lower three feet or so of the trunk which in its green, unseasoned, state is initially sawn into Fig. 3. Example of shaving horse. CONTEXT 40 Fig. 1. Radial split of trunk- largertree. Fig. 2. Radial split of trunk - smaller tree. blocks to the length required for one shingle. 5 These blocks can be radially split with an axe and wedge. The number of ROOF segments obtained depends on the original diameter of the tree bur a good average number would be eight. The considerable variation in the width of shingles used on a roof will depend on the initial size of tree. The inner point (centre of tree) of each segment is removed to permit the production of an even thickness shingle. This truncated segment is the base material from which the shingles will be riven, radially across the annular rings of the tree. A froe or dill axe6 is placed across the rings at approximately three shingles thickness from the edge. A beetle or mallet is used to initially drive the froe into the wood. It is then used as a lever to guide the split, by applying leverage in alternate directions to follow the natural medullary rays of the wood. The pieces so produced can then be split further by careful use of the froe and a brake (wood frame used to react against the leverage of the froe) to produce shingles. The finishing of the shingle consists of cleaning the faces (upper and lower) with SPACE 2 NAILS SHINGLE BOARO SHINGLE COURSE (OOUBLE J XPOSURE Fig.4. Shingleapplicationto roof 29
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