Although deterioration of timber-framing due to infestation is common, particularly in thin structural members such as braces, rot is the worst enemy. It is to be found in the sill-beams, the feet of the main posts and studs, and the upper surface of horizontal members on external walls, together with feet of braces and studs, and the joints between horizontal beams such as bridging joists, binders and girths with posts.
It is not of course a difficult matter to underpin a timber frame. Shorting can be applied to the girth or other suitable horizontal members, and the sill-beam can be disengaged from the posts and studs, removed and replaced with a new oak sill with mortices cut to engage the old tenons. At the same time, of course, the plinth, whether brick or stone, can be repaired or rebuilt and a new damp-proof course inserted beneath the sill-beam. If the sill-beam is in such poor condition that it needs to be replaced, it will probably be found that the feet of the posts and studs are also rotten, and a decision has to be made whether to cut them off to a common height and form new tenons or
scissor-scarf used for posts