Taking Mackintosh’s coat off
Encased in a metal, chainmail-style protective ‘box’ since 2018, the walls of the Hill House have now dried out sufficiently from almost a century of moisture ingress to allow the troublesome render – the concrete ‘skin’ applied over the building – to be painstakingly chipped off.
With National Lottery Open Week (7–15 March 2026) approaching, the Trust’s Chief Executive Phil Long OBE was joined in Helensburgh by Caroline Clark, Director for Scotland of The National Lottery Heritage Fund to inspect the works at close quarters.
L–R: Liz Davidson (Mackintosh Illuminated Project Director), Andrew Bradley (masonry contractor), Caroline Clark (Director for Scotland, The National Lottery Heritage Fund) and Phil Long OBE (Chief Executive, National Trust for Scotland) | Image: Alan McAteer
The Portland cement render was originally applied between 1902–04 under Mackintosh’s instruction. It was thought to be a ‘wonder’ product that would totally exclude the elements and allow the architect to achieve his vision of a building exterior without excessive ornament or detail – a style that was revolutionary at the time. Unfortunately, Mackintosh’s faith in the render was misplaced. Over many decades, the infamous west-of-Scotland rain found its way into the walls of the building and threatened irreparable damage.
The work to conserve and restore the Hill House is part of the National Trust for Scotland’s Mackintosh Illuminated project, which is generously supported by the players of The National Lottery through £1.1 million in development support from The National Lottery Heritage Fund. Launched in 2024, the project’s aim is to spotlight Mackintosh and Macdonald, sharing, celebrating and inspiring as many as possible with their creative genius and the beauty of their designs.
Phil Long OBE 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; 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.
‘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.
‘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.’
Image: Alan McAteer
Phil added: ‘In the coming months, we will continue our work with internationally recognised specialists to finalise a replacement surface render that will maintain the integrity of Mackintosh’s vision but will have the ability to ‘breathe’ – so ensuring moisture is not trapped and that the Hill House is fit to survive many more decades of west coast weather without the need for a protective box.’
A stonemason removing render at the Hill House in Helensburgh | Image: Alan McAteer
Commissioned in 1902 by wealthy Glasgow-based publisher Walter Blackie, the Hill House was carefully designed by Mackintosh to accommodate his patron’s family and their lifestyle. Mackintosh paid just as much attention to the building’s interior spaces as to its overall architectural form, designing furniture, textiles, stencilling and more to create complete designs. He collaborated on this with his wife, the professional artist and designer Margaret Macdonald (1864–1933).
The A-listed Hill House has been in the care of the National Trust for Scotland since 1982.
Liz Davidson, the National Trust for Scotland’s 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.
‘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.
We’re discovering new things every day as we peel away the render, including an unused entrance way and a window space we were unaware of.
‘I have been so glad to work with a team of such enthusiastic experts, such as Andrew Bradley and his team of masons.’
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