0 a beam supporting the roof of a house -- tagspær
wooden rafters.
But this rather crude structure puts more strain on the rafters and requires considerable strengthening of the walls to cope with the lateral thrusts.
This component of force along the rafter must be carried by a tenon with a comparatively small bearing area.
The top of the king post is splayed to receive the principal rafters.
It is not clear which direction the common rafters spanned between them.
The collar-beam supports a king-post reaching the top of the rafters, forming the ridge.
In that position the ends of the principal rafters are firmly restrained and their tendency to push the walls apart is most efficiently counteracted.
In engineering terms, there is a component of the strut forces parallel to the rafter.
These flowers are usually hung from the rafters to keep them free from contact with anything profane, thereby avoiding ritual pollution.
