The long principal rafters had to be flexible, so coconut wood (niu) was always selected.

The collar beam, which supports the opposing principal rafters, is supported by the crown post.

Sometimes the top cord (uppermost member) of a truss looks like a principal rafter.

From the hidden roof projected the principal rafters of the shallow-pitched eaves.

In the better sort of medieval roofs they are arched, and run from the principal rafters to catch the purlins.

Principal rafters are sometimes simply called "principals".

Later principal rafters and common rafters were mixed which is called a major/minor or primary/secondary roof system.

The king post is normally under tension, and requires quite sophisticated joints with the tie beam and principal rafters.

Common rafter (minor rafter): being smaller than a principal rafter.

A king post truss has two principal rafters, a tie beam, and a central vertical king post.

Roof purlins run the length of the barn and are tenoned into the principal rafters, with additional support from curved wind braces.

Architectural elements such as buttresses, crow step gables, and the principal rafter roof were characteristic of early 17th-century churches.

Frequently found in roof framing between on a tie beam and a principle rafter or from a king post to a principal rafter.

Principal rafter (major rafter, rarely a chief rafter): A larger rafter.

True cruck or full cruck: blades, straight or curved, extend from ground or foundation to the ridge acting as the principal rafters.

Auxiliary (cushon, compound, secondary, sub-) rafter: A secondary rafter below and supporting a principal rafter.

The wall plates support the roof trusses, consisting of a pair of principal rafters and an additional pair of intersecting "scissor rafters".

Common purlins are typically "trenched through" the top sides (backs) of principal rafters and carry vertical roof sheathing (The key to identifying this type of roof system).

Although the High Victorian style was becoming popular elsewhere, it played little part in Paley's designs, other than more elaborate decorative features, such as the embellishment of the principal rafters at Quernmore.

This revised dating means that the Coffin House may no longer be the earliest example of the principal rafter/common purlin roof, although even so it is certainly one of the oldest extant examples.

Roof trusses, as well as timber floors, can fail in a variety of ways, and failure by crushing at the joint of the principal rafter with the tie is assisted by any decay which affects this area.

In the interior roof of the solar room, the rigid 15th or 16th century structure of king posts, tie beams and principal rafters forms the main frame of the roof, as a series of triangular trusses.

The present roof, restored in the 1950s is constructed internally of massive tie-beams and a plastered ceiling, though the original was most likely a principal rafter roof similar to that of the third Bruton Parish Church.

Heyworth found at a farm in the village a stone-walled barn that had a modern arched corrugated steel roof, but had some stone corbels that would formerly have carried principal rafters of a former gabled roof.

The principal rafters are linked by a collar beam supported by a pair of arch braces, which stiffen the structure and help to transmit the weight of the roof down through the principal rafters to the supporting wall.