We have seen earlier that the transition from earthfoot timber-framed structures to sill-mounted structures and therefore a permanent framed building of box-frame construction occurred in England between about 1150 and 1250. As the name implies, box-frame construction consists of a box-like framework in which the roof load is distributed along the supporting walls, unlike cruck construction in which the walls are normally non-load-bearing and are, like the roof timbers, supported directly by the crucks from the ground. Box-framed buildings are based on the use of a pair of posts held together at the top by tie-beams and connected laterally at the top by wall-plates (on which the feet of the common rafters are supported) and at the bottom by the sill-beam. Further lateral support is generally provided by a girth or girt, a horizontal member placed about half-way between the wall-plate and sill-beam which also supports the first-floor joists. These basic components, together with various angle braces, form the frame, and the studs (secondary vertical timbers framed between the sill-beam, girth and wall-plate) and any other horizontal member only serve to reduce the overall size of the panels. The sill-beams are supported on a low plinth wall, to provide a level foundation for the building as well as to raise the structure clear of the earth.
Although the above members form the basic elements of all boxframed buildings in England, there is a great variety of forms not only in wall-framing but also in decorative styles, with many features subject to regional variations which changed with time, with one often intermingling with others to form hybrid patterns.
(12) The characteristic feature of medieval timber wall framing is the use of very large open rectangular panels (12A), in which the long sides, usually measuring some six or seven feet, are formed by the main posts, wall-plates, girths and sill-beams with the absence of common studs and with the main variation being the types of bracing used. A further characteristic is the free use of halvings, rather than
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I |
A. square open panel; B. herringbone pattern; C. scalloped; D. circular; E. cross-bracing; F. arch-brace; G. tension-brace; H. arch-bracing cusped; I. tension-‘orace with panel divided by one stud found in Kent and referred to as Kentish framing.