The Hill House Box

Carmody Groarke

The Hill House is arguably Charles Rennie Mackintosh’s residential masterpiece, one of Scotland’s most acclaimed buildings, Grade A listed, and a seminal part of early 20th century European architecture. A hybridisation of tradition and invention in the construction of the building has led to fundamental long-term problems of prolonged water damage. The National Trust for Scotland have determined that a major conservation project is needed to avoid irreversible destruction. 

Rather than incarcerate the house away from view whilst the restoration is undertaken, a more radical approach to active conservation has been taken. As an integral part of this conservation process, which could take up to ten years, a ‘big-box’ temporary museum to contain and protect the Hill House as an ‘artefact’ has been built. This allows the house to dry out and be conserved, whilst enabling visitors to see the conservation process first hand and maintain public access to the historic interiors. 

Alongside the aim of protecting the property, the project aims to bring new visitors to the house to experience the conservation process and attract underrepresented groups and young people to enjoy this historic building and gardens.  

The new museum’s architectural identity is that of a huge, abstracted garden pavilion whose walls are covered entirely with a stainless steel chainmail mesh. The cross-braced steel frame is designed to be grounded with minimum impact on the existing terraced garden. This semi-permanent enclosure provides a ‘drying room’ shelter to the original house, whilst its rain-soaked existing construction is slowly repaired. The chainmail reduces rain penetration, while allowing airflow for the building to breathe and dry naturally, providing sufficient light for trees to grow, bees to pollinate the garden and to naturally day-light the structure. This elegant enclosure also allows uninterrupted views, night-and-day, to and from the garden to Mackintosh’s architectural icon.

Within this safe shelter, the ‘museum’ provides a remarkable public visitor experience of conservation in progress, achieved by an elevated walkway which loops around and over the Hill House at high level. This allows visitors to see the Hill House in new ways, view damage to the existing construction, and conservators repairing the building. 

The museum’s enclosure also contains visitor facilities in a standalone timber building, arranged over three floors housing a reception, shop, café, visitor facilities and a roof terrace. The dark timber building contrasts the lightness of the chainmail and references experiences within the Hill House. 

Constructed in twenty-five weeks, building elements were pre-fabricated to reduce the impact of site construction to the historic building. Alongside the environmental benefits of saving the historic house we ensured that materials used can be recycled or reused once the structure is removed and conservation complete. The building has been designed to limit embodied and in-use energy demands for the historic Hill House and its temporary enclosure. 

The Box structure is fully demountable for reuse and recycling whilst the chainmail has been designed to be removed and reused due to the unique on-site stitching of the chainmail sheets. The visitor centre, constructed entirely from Scottish FSC timber has zero embodied carbon. In total the whole construction has a total embodied carbon rate of 470.1 kgCO2e/m2, nearly a third of a typical cultural project.

National Trust for Scotland, Argyll and Bute Council and Carmody Groarke worked closely to ensure planning permission could be obtained for this innovative conservation technique to protect the Hill House. The Hill House Box has dramatically increased the accessibility of a Grade A listed building allowing all visitors to explore the Hill House in new and unique ways. The new visitor centre houses a lift providing access to all floors and the gently ramped walkway. The walkway is designed to allow views in all directions for all visitors of the Hill House and surrounding landscape. All visitors using stairs or the lift, start and finish the experience at the same point, creating a universal experience. 

This £3.2million project aims to enhance the economic, social and cultural value within Helensburgh, in part through the anticipated doubling of visitor numbers and significantly diversifying those who will visit this historic piece of Scottish architecture. 


National Trust for

Structural Engineers

Price & Myers

M&E Engineer

Irons Foulner

QS / Project Manager /
Principal Designer

Gardiner & Theobold

Fire Engineer

Atelier Ten

Civil Engineer

David Narro

NEC Supervisor

Sentinel Clerk of

Café and shop fit out

Drinkall Dean

Graphic Designer

Carter Studio

Main Contractor


Gross Internal Area


Contract Value


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