Roundhouse (windmill)

Early medieval post mills had their trestles partly buried in the ground.

This gave the mill stability, but had the disadvantage that the trestle would rot where it met the ground.

[4] Single storey roundhouses had two doors directly opposite each other to give safe access and egress whichever way the wind was blowing from.

The latter were most common amongst windmills in Suffolk, where the post mill reached its peak of design.

[7] Generally, the roundhouse has no structural function, with the exception of roundhouses in the Midlands region of the United Kingdom, where they carried a curb and through wheels on the underside of the buck of the mill, they carried some weight from the mill, a task usually performed solely by the trestle.