top of page
  • Writer's pictureAmy Boyce

Sylvester Manor Windmill, Shelter Island, NY

The windmill was moved locations in its past, and in recent years the rubble stone footings were replaced with concrete piers and capstones of schist. At some point during the above, the mill got out of level to an extent which caused the vertical drive shaft to be pressed against the sprattle beam. This binding prevented the vertical drive from turning. The cap which operates on a unique historic internal winch system was also bound. Thus the mill was inoperable. (There is mechanical work needed prior to the full restoration to working order).

In addition to the leveling issues, the mill's beams were in direct contact with the stone caps. To address this and the leveling, we jacked the mill from 18 locations, leveled it, leveled the stone caps with mortar, installed a copper barrier between all points of stone-to-wood contact, and added rot resistant pads. Prior to jacking, we temporarily shored in the mill's interior to carry loads throughout the building. The pads made of locust and white oak serve as shims for leveling and as sacrificial spacers. These pads were treated with Boracare.

The schist cap stones in many places protruded from the plane of the shingled sidewalls. This allowed rain to flow under the beams of the mill and increase moisture content in the wood. Rather than re-foot the mill with a more historic treatment (to keep the project within the budget), we cut back the schist and refaced it. As a final step, we flashed above each exterior pier to prevent precipitation from getting in.

We also addressed a rotten sill and studs. This sill, positioned under a former window that leaked, had shear failure. The studs that tenoned in and sub floor and floor had also rotted. To repair, we removed the old sill and cut a new one (band sawn white oak). To be able to slip the sill in, we cut open the mortices in the beams and dovetailed them and slanted them up to the terminus to ensure the sill fit as snuggly as possible. Since three tenons come into the same area on the beams, we backfilled the open mortises with dried white oak which also wedged in, thus maximizing support under the load of the cant posts.

See the photos and videos below for more!


Sill and Stud Work (photo order from finished to start)

56 views0 comments

Recent Posts

See All


bottom of page