crownposts

A crownpost is a structural timber element used in traditional roof construction, particularly in medieval and early modern buildings. It is a vertical post that extends upwards from a tie beam or collar beam, supporting the apex of a roof. The crownpost is typically situated at the center of the roof span, forming a crucial part of the roof's structural integrity.

The function of a crownpost is to prevent the rafters from spreading outwards under the weight of the roof covering and any snow or wind loads. It achieves this by transferring the outward thrust from the rafters to the tie beam below, which is a horizontal timber that spans the width of the building and connects the bases of the principal rafters. The tie beam is often further supported by wall posts or internal walls.

Crownposts can take various forms. Some are simple, straight timbers, while others are more elaborately shaped or decorated. They are often associated with hammer-beam roofs, where they can be integrated into the complex system of levers and counterweights. In some designs, the crownpost may also support a king post, which extends further upwards to a ridge piece. The presence and style of a crownpost can be an indicator of the age and architectural significance of a building.