Cruck Frame or Post and Truss?

Cruck and Post and Truss are the two main types of timber frame buildings in the UK – depending on age of construction and location.

Cruck construction
These are cross frames made up of pairs of curved timbers, it is said to originate from boat building techniques and it’s not hard to see why. The frame looks a little like an upturned boat.

These timbers meet at the apex and are tied together by a collar. This frame supports purlins and wall plates. It looks like a letter ‘A’. Using this construction method, Cruck frames transfer the load from the roof to the ground.

Post and Truss
This is the most common timber frame form and makes use of purlins. Roof and walls are structurally combined within each cross frame. The cross frames include tie beams. Main rafters are joined or tied  into a  beam and this forms roof trusses to carry purlins which in turn support the rafters.