Free medical insurance http://myvidster.fun my vidster My first port of call with any timber related query is the Timber Research and Development Association (Trada). Apparently yew, although durable, is not often used as it has a strange grain pattern due to all the knots (where branches join the trunk) which can result in it bending as it slowly dries out. Oak and sweet chestnut, though, are extremely durable and they do not need treating. In any case these woods are so dense that preserving chemicals cannot penetrate. This is a big advantage, in terms of the environment, as there have been issues with the chemicals used in the preservative processes. This helps make hardwoods more competitive in economic terms.