C O N T E X T 1 3 4 : M A Y 2 0 1 4 15 conversion marks, ritual or apotropaic (evil-averting) marks? How can we accurately record marks that we do not understand, or possibly even recognise? If the two basic approaches, the genuinely traditional and historically more common ‘repair by addition’ and the currently more prevalent ‘repair by replacement’, are compared with the basic principles of conservation set out above, it becomes apparent which offers the more conservative solution. In repair by addition: •• There is little or no loss of original fabric. •• The additional elements can usually be installed with little or no disturbance to the surrounding fabric. •• If correctly designed, it is reversible: the added elements can be removed at any time and an alternative method of repair adopted. The use of carpentry repairs unavoidably involves the loss of a proportion of the original timber. This raises many difficult questions as to how the new timber should be sourced, specified and finished, and whether details and features of the old timber should be replicated on the new. For example: 1. Should the new timber be converted with the same tools as the original, to leave the same finished appearance? If not, why not?Why is band-sawn timber thought acceptable on the exposed face of an Elizabethan timber-framed house, when new bricks used to repair a Georgian facade must be hand-thrown with a surface finish that closely matches the original? 2. Is it acceptable to use green timber for a new element that will then shrink up to 10 per cent over the next year or two, imposing additional stresses on surrounding fabric? 3. If one half of a scarf joint is cut in dry and stable timber and the other in green timber prone to asymmetric shrinkage, is it likely to function satisfactorily? If not, is it acceptable to use laminated dry timber, and/ or steel bolts and shear connectors? 4. If the replaced section contains a redundant mortice, should that be replicated? If not, the information is lost to future historians. While it should always be the case that any repair works be accompanied by a comprehensive photographic, drawn and written record of the pre-repair state of the building and the repairs carried out, this very rarely happens, even on historically important or prestigious buildings, let alone more modest structures. If the removed section is deemed to be of particular importance, it could be physically stored on site after any necessary consolidation. But if deemed that important, perhaps a method of repair that involved its removal should not have been used. 5. If the decision is made that relatively gross features such as redundant mortices be replicated, how are they to be identified as pre-dating the repair? 6. Is the recording of a redundant mortice historically more important than finer details such as layout and The blacksmith-forged bracket was probably fitted to this 17th-century jettied farmhouse in the 19th century. It has done its job well for more than 100 years. It is a pragmatic and economic repair, saving all the surviving original timber and surrounding fabric. It is reversible, but it would be difficult to find a more conservative repair to replace it with. The joint used for this new section of jetty bressumer is both weak and unnecessarily complicated. The shrinkage in the new green oak section is already opening up the joint interfaces. As most if not all the historic record held in a timber is at or near the surface, repairs should be designed to minimise the surface lost. In this carpentry repair, the necessary new timber has been inserted behind the surface.This approach is likely to weather better and be visually less intrusive than a face repair.
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