Project leaders from Feilden Clegg Bradley Studios, AKT II, Arkoni, and Schüco discuss the collaborative processes and technical challenges behind the façade of Shrewsbury Flaxmill Maltings, Shropshire, with AT’s Technical Editor John Ramshaw.
In association with
At the heart of most successful façade designs is a story of collaboration, teamwork and ingenuity. In this new technical series, sponsored by Schüco, we explore these important and revealing processes through a standout project submitted for the Schüco Excellence Awards. The fifth article in the series explores Shrewsbury Flaxmill Maltings, a major repair and adaptive re-use project in Shropshire. Completed in 2023, the 5,600-square-metre scheme was designed by Feilden Clegg Bradley Studios (FCBS) for Historic England, and delivered in collaboration with structural and civil engineer AKT II, specialist façade contractor Arkoni, main contractor Croft Building & Conservation, and façade, window, and door solutions provider Schüco.
Reviving an industrial icon
Constructed in 1787, the former flaxmill was the world’s first multi-floored iron-framed building, paving the way for tall, modern-day steel-framed structures. Following the collapse of the flax industry in the late 1890s, the five-storey mill was converted into a maltings, which remained active until 1987. After more than 20 years of decline, it was decided to repurpose the building with the aim of kick-starting the local economy. The £28m repair and adaptive re-use scheme includes a café and exhibition space at ground level, with four floors of office space above. Circulation and meeting spaces are located in the adjacent kiln building.
FCBS targeted a fabric-first strategy as a means of retaining as much of the original façade as possible. Extensive strategic surveys – carried out to assess the condition of the masonry –identified widespread areas of bulging and embedded timber decay. “The use of embedded timber within masonry walls was common practice in 18th-century construction,” explains Chris Blust, Design Director at AKT II. “Here, the timber had been subjected to moisture over its 200-year life. This, combined with the infilling of windows during the mill’s conversion to a maltings, created conditions that caused the internal cast iron frame to move differentially and crack.”
AKT II worked hand-in-hand with Historic England, FCBS, and Croft Building conservation, to devise an appropriate means of removing the decayed timber, while maintaining the structural integrity of the building. “The masonry structure was being delicately held together by a propping scaffold, and required a carefully choregraphed 13-step procedure to remove the timber lintels and bearing pads at each column line,” says Blust. “To test and potentially improve the proposed methodology, Historic England engaged Croft Building Conservation to carry out a trial works. As part of the operation, Croft wove a separate needling frame into the propping scaffold and displayed a level of craftsmanship that allowed for seamless integration of old and new materials.”
Alongside the issue of decayed embedded timber was the problem of window modification and load redistribution. During the maltings conversion, most of the original windows had been infilled with heavy masonry, significantly increasing the load on the perimeter walls, and ultimately leading to differential settlement. The restoration process involved carefully removing the masonry infill while ensuring that the surrounding walls remained stable. “These two main challenges could not have been overcome without visualising and drawing through the specific sequence of works,” comments Geoff Rich, Partner, Director of Heritage & Creative Reuse at FCBS. “The team drew out all the conditions encountered, the 13 construction stages, and the final condition. This allowed for methodical interrogation at both architectural and structural levels.”
Fine tuning the window specification
Forming a key part of the restored façades are more than 100 new, high-performance steel windows from Schüco. Working alongside FCBS and Historic England, Arkoni manufactured and supplied the Jansen Janisol Arte 2.0 units, which provide excellent daylighting and natural ventilation. “The team considered it important to retain the look of the existing building, while also providing higher performance for the glazing elements,” says Simon Black, Team Leader – North, Metal Construction, at Schüco. “This led to the selection of Janisol Arte 2.0 steel windows from our Schüco Jansen range. The thermally-broken units offer superior thermal performance, while maintaining the slim sight lines and overall aesthetic of the original windows. Furthermore they are finished in a RAL colour matching the original windows.”
“It was decided to incorporate Schüco Jansen’s espagnolette multi-point locking system due to the window heights from the floor slab(s),” continues Black. This enables the vents to be secured using one easily-accessible handle – without having to over reach. The vents also feature a Jansen top stay, to stop the windows opening too far. By collaborating with Croft Building & Conservation and FCBS, we agreed this was the solution needed for functionality and performance.”
Safety was also a key consideration. Lee O’Donnell, Managing Director at Arkoni says, “We were confident that the windows met the required 1.5 KN line load when closed, but had a concern for public protection when they were open. This led us to incorporate an additional, adjustable bottom stay on each unit. The windows themselves are glazed using a laminated Sunguard product with the latest warm-edge thermal spacer bar technology. This helps to reflect the sun’s rays, while keeping the interiors cool in the summer and protected from damaging ultra violet light.”
Overcoming site challenges
The construction phase presented a number of challenges related to site constraints, material handling issues, and unforeseen conditions that required real-time problem-solving. While the dense propping scaffold that had been erected around the building to prevent its collapse during the initial stages was essential for maintaining stability, its design – 15 years prior – had naturally not taken into account future works and repair sequences. “The scaffold significantly restricted access to the façade, making it difficult for labourers to manoeuvre materials and carry out repairs efficiently,” explains Rich. “While the trial works period helped to set this expectation, further efficiencies were always sought, including getting the original designer to make scaffold adaptations where practical and possible.”
The project also faced challenges related to ground conditions, particularly in areas where new temporary foundations were required to support the needling frame. “One side of the building allowed for traditional pad foundations, while the other had to rely on temporary screw piles due to the presence of a significant amount of made ground,” says Rich.
Protecting the original building fabric was also paramount in terms of installing the new fenestration. This led to the adoption of concealed through-frame fixings for the windows, eschewing the need for traditional fixing straps. “It’s always challenging to refurbish existing buildings,” comments Black. “We rely heavily on our specialist subcontractors, such as Arkoni, to offer the best solution when it comes to installation and factory fabrication. These types of projects typically require experienced fabricators to ensure everything is completed correctly and in line with our instructions. Schüco specialises in offering ‘value up’ solutions, where we utilise our extensive range of products for the refurbishment market. This means existing buildings do not have to be demolished and rebuilt but can be upgraded to perform to current building regulations and performance.”
Reflecting on success
The overall success of the project was due in no small part to the high levels of expertise contributed by each member of the team. This ranged from innovative thinking to expert crafting and manufacturing. For Blust, it was the team’s commitment to achieving the best possible outcome that really stood out. “Each member adopted an unwavering position, digging-in and overcoming challenges as they arose,” he says. “This made the design team work together as partners in pursuit of success, rather than as a team of individual consultants.”
This viewpoint is echoed by Black, “Collaboration between ourselves, Arkoni, and the rest of the project team played a key role in the success of the project – bringing the historic fabric up to modern performance standards, and preserving an important heritage asset for generations to come.”
The final words go to Rich, “With more than 200 years of history already behind it, the most remarkable achievement of the project was extending the life of this historically significant structure into a third century; ensuring that it maintains a strong connection to its past, and preparing it for a sustainable future.”
