This site has been how to use a framing square pdf by the network administrator. These posts are then generally secured by a horizontal beam which then forms an “A” shape. Several of these “crooks” are constructed on the ground and then lifted into position. However, these bent timbers were comparatively rare, as they were also in high demand for the ship building industry.
Where naturally curved timbers were convenient and available, carpenters continued to use them at much later dates. Despite these changes, an authority on English Historic Carpentry, Cecil Hewett, has stated that these 16th-century crucks are original. No cruck frames are known to have been built in America though there are rare examples of what may be an upper cruck or knee rafters. During the current revival of green oak framing for new building work, which has occurred mainly since approximately 1980 in the UK, genuine cruck frames have quite often been included in traditionally carpentered structures. There are also some fine, historically authentic reconstructions. The necessary trees were sought out, using special templates, in English woodlands.
True cruck or full cruck: The blades, straight or curved, extend from a foundation near the ground to the ridge. A full cruck does not need a tie beam and may be called a “full cruck -open” or with a tie beam a “full cruck – closed”. Base cruck: The tops of the blades are truncated by the first transverse member such as by a tie beam. Raised cruck: The blades land on masonry wall and extend to ridge.
Middle cruck: The blades land on masonry wall and are truncated by collar beam. Upper cruck: The blades land on tie beam, very similar to knee rafters. In Dutch called a kromstijlgebint. Jointed cruck: The blades made from two pieces joined near eaves. They can be joined in at least five ways. The apex of a cruck frame also helps to define the style and region of the cruck. Different types include the butt apex, halved, housed, yoke, and crossed forms.