A project to dry out Charles Rennie Mackintosh’s masterpiece the Hill House has reached a “critical juncture”, with conservators having to painstakingly remove the cement render that was a major factor in extensive water damage.
A giant steel box around the property in Helensburgh, Argyll and Bute, was completed in 2019 to protect the building’s saturated walls from further damage from the elements and to allow it to gradually dry out as part a long-term conservation programme.
The Hill House has been badly affected by the driving rain on Scotland’s west coast since its construction in 1904.
Materials and techniques that were at the cutting edge of architectural design in 1900 have not withstood a century of the west of Scotland’s wet weather
ANDREW MILLIGAN/PA
A Portland cement render, or “skin”, was applied to the building in 1902-04 under Mackintosh’s instruction, when it was thought to be a wonder product that would protect against the elements.
However, the render did not live up to expectations. Water penetration over the decades damaged both the structure of the house and the bespoke interior decoration.
After several years of being sheltered by the steel box, the walls of the Hill House have dried out enough for the render to be painstakingly chipped off. The removal of the render is now well under way.
The house was commissioned by Walter Blackie, a Glasgow book publisher, and the interior design was a collaboration between Mackintosh and his wife, Margaret Macdonald.
Caroline Clark, director for Scotland at the National Lottery Heritage Fund and Phil Long, chief executive of the National Trust for Scotland
ALAN MCATEER/NATIONAL TRUST FOR SCOTLAND/PA
Phil Long, chief executive of the National Trust for Scotland (NTS), which cares for the property, said: “It’s difficult to overstate the international importance of Mackintosh and Macdonald and of the Hill House, and so delivering this project is of vital importance in preserving Scotland’s — and the world’s — design heritage.
“From the moment they were realised, Mackintosh’s designs had a profound effect on the development of early 20th-century international architecture and design, and more than a century later, they remain startling.
“The Hill House is one of the architect’s greatest remaining masterpieces, and in its breathtaking interiors, realised in collaboration with his wife, the artist and designer Margaret Macdonald, their combined vision reached its peak.
“This is why restoring this building is of such vital importance to Scotland’s and the world’s creative heritage.”
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Long continued: “Thanks to the National Lottery Heritage Fund’s generous support, the project has reached a critical juncture. The removal of the render allows us to explore the detailed construction of the building and gain further insight into Mackintosh’s architectural innovation, as well as the constraints he was overcoming.
A stonemason at work removing the Portland cement render from the walls
ALAN MCATEER/NATIONAL TRUST FOR SCOTLAND/PA
“The protective box has controlled the drying out of the building, which, if done too fast, may have caused further damage.
“After expert analysis, it was clear that full replacement of the often-patched Portland cement render was the only tenable option for enabling the restoration work that ensures the building’s long-term survival.”
NTS said it would continue to work with internationally-recognised specialists to finalise a replacement surface render that would maintain the integrity of Mackintosh’s vision, but would be able to “breathe”.
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Long said this would ensure moisture was not trapped and that the Hill House was fit to survive many more decades of west coast weather without the need for a protective box.
The house has been closed to visitors while conservation work has been under way, but the walkways, café, garden and shop have stayed open.
The work to conserve and restore the Hill House is part of the NTS’s Mackintosh Illuminated project, which is supported by the players of the National Lottery.
Liz Davidson, NRS project director for Mackintosh Illuminated, said: “The Hill House’s restoration is just one aspect of the Mackintosh Illuminated project, which we aim to roll out over the next two to three years.
“By 2028, on the 160th anniversary of Mackintosh’s birth, the Hill House should no longer need its protective box and, ahead of that, with the National Lottery Heritage Fund’s support, we will be completing internal conservation work and developing new and accessible interpretative and learning materials, as well as a programme of community engagement.”