Largest sheet of chainmail

The largest sheet of chainmail measures 2,700 m^2 (29,062 sq ft), and forms the exterior of the "Hill House Box" erected around Hill House in Helensburgh, UK. This enormous chainmail and steel structure was designed by Carmody Groarke Architects for the National Trust for Scotland, in order to protect the historically significant house during restoration. It was completed on 31 May 2019.

Hill House was one of the masterworks of Scottish architect and designer Charles Rennie Mackintosh, a country home built for publisher Walter Blackie between 1902 and 1904. Mackintosh designed not only the building, but – along with his wife Margaret MacDonald – all its interior furnishings and interior detailing. The result is one of the most important and complete examples of British art nouveau.

During construction, Mackintosh made the decision to render the exterior of the house with Portland Cement, a then-new construction material which proved unable to keep out the driving rain that this part of Scotland is known for (with almost 200 days of rainfall a year).

As a result, the fabric of the building has been slowly degrading, putting its structural integrity at risk. The importance of this building was only increased in 2018, when Mackintosh's other great work -- the Glasgow School of Art, was destroyed in a fire. In 2019, the National Trust for Scotland and architects Carmody Groarke installed "The Box", which consists of a steel roof and chainmail walls, to protect the structure from the elements and to allow it to dry out.

Using chainmail for the walls allows for air to circulate around the building, and also for light and pollinators to reach the plants in the garden. It prevents rain from blowing in from the sides.

The mesh comprises some 32.4 million steel rings, and was sown together from multiple smaller sheets to create a single continuous sheet that envelops the whole house. It weighs 8.3 tonnes and is designed to be unstitched and reused when the restoration work is complete.