The style of cap varies from region to region, tower mills in the midlands usually have an 'ogee' shape whereas those in the north west and south east are boat shaped. 

Frame for a new 'ogee' cap
'Ogee' cap ready to lift back on the milll
Rarely seen view as the cap is lifted back on to the mill
Cap in situ on Callington Mill ready for new sails
Interior of 'ogee' cap frame
Lifting Pilling mill cap back into position

A fully restored windmill the cap will need to support the weight of the sails, wind-shaft and the turning gear. The main timbers running front to back (sheers) need to be substantial to cope with the weight and the stresses of the wind.  Instead of replacing the entire cap it is often better to replace the sheers and repair the cap frame. 

For Pilling Mill, which is a house conversion, we constructed the cap using a steel frame. This allows the owners to use the space inside and have a fantastic viewing gallery from the fan stage.

If the cap is purely to keep the weather out then a lighter construction may be used. 

Repairing the cap is more easily undertaken with the cap on the ground. The cap and all its machinery can be lifted on and off the tower with a large crane.