The National Trust for Scotland has reached another landmark in its project to save The Hill House, designed by Charles Rennie Mackintosh, with the successful removal of the original cement roughcast, a major milestone in addressing the building's longstanding moisture problems.

The achievement, made possible thanks to the support of The National Lottery Heritage Fund, can be seen in a timelapse video released today by the conservation charity. The footage condenses 5.5 months of work by an expert team of stonemasons, led by Andrew Bradley, into under a minute.

The full roughcast removal is a major step forward in the project to save The Hill House and, as part of Mackintosh Illuminated, is one of the most significant conservation projects currently underway in Scotland.

Designed by Charles Rennie Mackintosh for publisher Walter Blackie and completed in 1904, The Hill House is widely regarded as his finest domestic commission. In the care of the National Trust for Scotland since 1982, the house has become one of the country's most treasured architectural landmarks and an internationally recognised example of early twentieth-century design. Yet for decades, it has also presented one of Scotland's greatest building conservation challenges.

placeholder image — Photography Kirsty Anderson

The Trust’s efforts to save The Hill House have been significant. The original Portland cement roughcast, deemed innovative in its day, trapped moisture within the building's walls, contributing to extensive deterioration to the structure over time. Finding the right solution has required many years of research, testing and collaboration between conservation specialists, architects, engineers and craftspeople. The award-winning Hill House Box was completed in 2019 to protect The Hill House from the elements and allow the building fabric to begin drying out, while pioneering research was carried out to understand the condition of the house and determine the most appropriate long-term approach to its conservation.

The significant work to save The Hill House is the conservation anchor of Mackintosh Illuminated, the Trust’s ambitious project to conserve, celebrate and share the legacy of Charles Rennie Mackintosh and Margaret Macdonald Mackintosh. Supported by The National Lottery Heritage Fund, the project centres around two of Scotland's publicly accessible Mackintosh sites, The Hill House in Helensburgh and the Mackintosh Tearooms on Sauchiehall Street, Glasgow. The charity is working with partners across Glasgow and beyond to inspire new audiences through conservation, learning, interpretation, digital innovation and cultural collaboration.

The completion of this phase marks a major milestone in the project. After seven years protected by the Box, the Trust can now continue the next critical phase to make The Hill House watertight from the Scottish weather. The team will monitor the building inside and out, while working with experts to develop a long-term replacement roughcast that responds to Mackintosh's original design while protecting the building fabric.

The Trust is seeking to raise £14 million towards the £20 million cost of the Mackintosh Illuminated project and is grateful for support already confirmed from The National Lottery Heritage Fund and early leadership gifts from private individuals, including an anonymous donation of £625k in June this year. The charity invites everyone with a passion for the legacy and influence of Mackintosh and Macdonald to join in supporting the next phase of the project, to help make the next phase of this vital conservation work possible.

Phil Long OBE, Chief Executive of the National Trust for Scotland, said: "The Hill House is one of Scotland's most important architectural treasures, and the completion of the roughcast removal marks a significant moment in its conservation. It follows years of careful research, monitoring and specialist work to better understand the building and determine how best to protect it for the future.

"Mackintosh Illuminated builds on this work, not only by securing the future of The Hill House, but by deepening the understanding of Charles Rennie Mackintosh and Margaret Macdonald Mackintosh and their remarkable contribution to art, architecture and design. There is still a great deal of work ahead, and we will continue to need the support of our partners, funders and donors as the project progresses.

"In recent months, we have all been reminded how precious and precarious Scotland's built heritage is. The work at The Hill House demonstrates the complexity, expertise and commitment required to protect buildings of this significance. With continued support, we can ensure that The Hill House and the wider legacy of Mackintosh and Macdonald are protected, understood and shared for generations to come."

Visitors can explore The Hill House, including the unique walkways of the Box daily in Helensburgh. Entry is free for National Trust for Scotland members.