The Hill House, near Helensburgh, is arguably Charles Rennie Mackintosh’s residential masterpiece and one of Scotland’s most acclaimed buildings. In a radical approach to conservation, Carmody Groarke has cloaked the house in the world’s largest chainmail structure, giving the National Trust for Scotland the time and space to address decades of water damage and avoid irreversible destruction. Within The Hill House Box ‘museum’, Mackintosh’s building becomes the exhibit, where high-level walkways and other visitor facilities allow the public to appreciate the building and see conservation work up close.

The National Trust for Scotland, which was faced with a very difficult problem in how to preserve The Hill House, which was in imminent danger of collapse. To repair it and be true to Charles Rennie Mackintosh’s details implied a regular and unaffordable pattern of continual closure and reconstruction. Following a design competition, the National Trust for Scotland showed considerable bravery in adopting Carmody Groarke’s concept of enclosing the entire building to protect it from the weather, while allowing the public to climb around it. This has been a notable success, in that it has reduced the moisture in the walls, allowed repair without closing the building, and creating much needed additional space for a café and shop – while substantially increasing visitor numbers.

The Client of the Year Award is sponsored by the Scottish Government.

Culture minister Jenny Gilruth said: “The Scottish Government sponsors the RIAS Client of the Year Award in recognition of the key role the client plays is securing the wider benefits of good design and architecture.

“I’m delighted to see the National Trust for Scotland win the award in 2021 for the unique and innovative Hill House Box project in Helensburgh which has allowed essential and extensive repair work to be carried out whilst maintaining public access to Charles Rennie Mackintosh’s masterpiece.

“I congratulate the National Trust for Scotland for taking an exemplary approach which has increased visitor numbers to The Hill House.”

RIAS president Christina Gaiger PRIAS said: “Not so long ago it looked as if the future was bleak for The Hill House. It would have been unthinkable to lose Charles Rennie Mackintosh’s masterpiece, and it’s thanks to the bravery of the National Trust for Scotland and the imagination of Carmody Groarke that its future is now secure. Together, their imaginative and radical approach has ensured vital conservation work can happen while bringing the public up close to this fascinating process.

“The Hill House Box is one of the most unusual projects to have won a RIAS Award, and I am delighted to see the project also earn the RIAS/Scottish Government Client of the Year Award for The National Trust for Scotland. The best clients are those who dare to think differently, and The Hill House Box is a physical manifestation of how clients and their architects can work together to create magic from even the most challenging brief.”