Crook frame

A Crook Frame or Cruck is the timber framing or ‘structure’ of a building which consists of long, generally bent, timber beams that lean inwards and form the ridge of the roof. 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. They are then joined together by either solid walls or cross beams which aid with preventing racking. Racking is the action of each individual frame going out of square with one another and thus risking collapse.

These bent timbers were comparatively rare as they were also in high demand for the timber ship building industry (used like an upside down capital 'A')

The term crook comes from an implement or tool, such as a bishop's crosier or a shepherd's staff, with a bent or curved part; a crook.

References

References:Ross, P., Mettem, C. and Holloway, A. (2007). Green Oak in Construction. TRADA Technology. ISBN 978 1900510 45 5.Hewett, Cecil A. (1980). English Historic Carpentry. Philimore, 231-233. ISBN 0 85033 354 7.