Winchester City Mill’s major structural restoration 2018
Dating back well over a thousand years, City Mill has weathered the course of time. Following flood damage in 2014, Winchester was at risk of losing one of its most historic properties.
Immediately after the flooding, we began to assess the damage to the building and machinery. The lower millrace floor, including the waterwheel, gearing and a supporting beam and post over the slow race required significant repairs. It took nearly a year to return this part of the building to full use.
Once this work was complete, we turned our attention to the old Youth Hostel basement area, adjacent to the millrace. This area has not been publically accessible since the end of the hostel’s tenancy. Much of the space comprised of panels and partitions containing asbestos, which had, for many years, made assessment of the supporting beam structure behind impossible, until now.
Removing the asbestos proved a major undertaking and it quickly became apparent that the ancient oak beams and joists were in a terrible state of decay. The deterioration to the Mill’s supporting structure was so severe that over 50 acrow props were required to stop the building collapsing under its own weight.
A series of structural surveys and assessments quickly followed so we could thoroughly understand the severity of the situation. We soon realised that making the repairs would be a major project. We launched our ‘Save City Mill’ fundraising appeal in January 2017 and were amazed by the level of public support. The campaign was supported by our visitors, numerous Winchester businesses, as well as local community groups and National Trust supporter groups.
Within 9 months, the total raised was in excess of £90,000. We were also fortunate to secure a flood resilience grant from the National Trust and work began in earnest in March 2018.
The majority of the building’s fixtures and fittings were removed and over half the floorboards lifted exposing the deteriorated oak beams and joists beneath. The last time the Mill would have been seen like this was most likely in 1744 when it was restored by James Cooke. In many places the floor consisted of three layers of floorboards. We saved and reused as much of the historic woodwork as possible but some of the boards and joists were just too far gone.
Traditional carpentry methods, such as, a chisel and mallet, were used to fabricate the new oak beams, joists and lintels to reinforce the Mill’s original structure. New oak inserts replaced rotten sections that were not possible to retain. Each insert was individually carved and secured in place with bolts. In order to preserve as much of the original fabric of the building as possible, the new joists have been supported on stainless steel hangers, which sit like a saddle over the original oak beams. As a result, the majority of the original timbers have been preserved and the new joists carry the load of the floor.
Our millwright Ian Clark and master carpenter Bob Hall were commissioned to design a new dividing partition for the mill room. The new partition is a blend of contemporary and modern design in the form of a traditional solid oak frame, which incorporates modern glass infills and doors to provide a clear view through the building. The frame is constructed from 5 year air dried English oak grown on the Bowood Estate in Wiltshire.
With the floor and walls secured, we turned our attention to the basement. Varying levels of concrete floor were broken up and levelled out, revealing the 18th Century floor beneath, made up of Flemish red bricks, hand-laid cobbles and limestone slabs. Visit City Mill on a baking demonstration day and you’ll be able to experience the new basement area for yourself.
With the restoration finally completed in September 2018, we began a series of flood resilience works. This involved reinforcing the arches of the millrace area and improving the building’s weed screen protection so that City Mill is prepared for any future flood event.