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Repairs to Bourn Windmill

Repairs to Bourn Windmill

August 5, 2022 Rachel Finlay Comments Off

Project: Timber repairs to Bourn Windmill 

Location: Caxton, Cambridge



This open trestle post mill is the oldest surviving windmill in the UK, and is Grade I Listed and designated an Ancient Monument. The entire weight of this windmill is supported on a central post, which is supported by a trestle. The repairs will involve the raising of the buck by approx. 100mm clear of the main post to carry out urgent repairs to the timber trestle.

Repairs to Bourn Windmill include installing replacement trestles constructed from air dried oak (minimum 4 yeas fallen). A traditional joint will be formed by hand and held in place with iron brackets & rods. Bakers will construct four replacement brick piers) which will need to cure for 28 days before any loading is placed on them.

How Trestle Post Mills Work

The post mill is the earliest type of European windmill. It’s defining feature is that the whole body of the mill that houses the machinery is mounted on a single vertical post, around which it can be turned to bring the sails into the wind. It takes around two or three people to turn the mill around to bring the sails into the wind, and although it is a dramatic job it is fairly easy to do so. All post mills have an arm projecting from them on the side opposite the sails and reaching down to near ground level.

Bourn Mill Project Tours

The mill is currently closed whilst repair works are being carried out to the rotted timber trestle – however the general public enjoyed seeing the work in action during two project tours which took place in July and August 2022.

History of Bourn Windmill

The earliest written record of Bourn Mill was made in 1636. This style of mill has barely been changed since the 13th century. In 2021, scientists attempted to age the timbers in the mill and concluded that the tree that provided the huge timber for the main post in the mill was cut down during 1513-49, making it the oldest wood in any mill in the UK. Various structures and parts on the mill were replaced over the centuries as they wore out or rotted. The machinery dates from the 19th century and the trestle was renewed using oak in 1874.

Save Bourn Mill

Works to the save the mill are being supported by significant grants from the Lottery Heritage Fund and Historic England. To find out more about the Save Bourn Windmill Appeal click here.