Rafter Holes

The crown-post roof appeared in England in the second half of the thirteenth century and persisted until the early sixteenth century in the south-east of England. Rafter holes are found in these roofs near to the feet of the rafters on their lower faces. They are blind holes typically 75 mm to 100 mm deep by about 25 mm in diameter. Various theories have been put forward over the years to explain their function. This paper reviews the evidence found on the rafters and integrates it into a revision of one of the earlier theories which suggested that rafter holes formed part of a jig or templet. This jig was used to ensure that the collars were at the correct height relative to the crown plate (or collar purlin). These ideas have been applied in the prefabrication of a new crown-post roof. Evidence is also presented showing how the practice of using jigs to help prefabricate rafter cross-frames may also have been applied to some other roof types such as scissor-braced and side-purlin roofs, in south-east England.