Derelict mill saved through historic conservation efforts

Howells Patent Glazing has supplied rooflights for the regeneration of the award-winning Flaxmill Maltings mill in Shrewsbury. Specify & Build reports. 

Opened as a flaxmill in 1797, the main mill at Shrewsbury Flaxmill Maltings was the world’s first iron-frame building and is now considered the grandparent of the modern skyscraper. An internationally important industrial heritage site, the building was derelict for many years before English Heritage (now Historic England) bought the freehold in 2005. 

In partnership with Shropshire Council and the Friends of the Flaxmill Maltings, and with funding from The National Lottery Heritage Fund, Historic England embarked on a mission to save the Grade I-listed Main Mill and adjoining Kiln, to create work and community spaces that celebrate the past.  

Project architect Feilden Clegg Bradley Studios were tasked with developing and delivering an “exemplar of sustainable refurbishment to support the next 100 years of use for a building with a particularly innovative design heritage”.  

Specialist manufacturers and suppliers were key to the conservation and heritage-led regeneration of the site which includes eight listed buildings. Howells Patent Glazing was appointed by contractor, Croft Building and Conservation to design, supply and install two new rooflights. 

Reinstate natural light 

Originally, large windows admitted natural light for the flaxmill employees but, a century later in 1897, the building was converted into a maltings. Changing the site from a mill to a maltings meant major alterations. For example, two-thirds of the large windows were blocked up and the remainder made smaller; the boiler houses were demolished; and a large pyramid-roofed kiln was built.  

Today, the addition of new rooflights allows daylight to filter once again into the buildings. Perhaps the most dramatic of the two installations is the flat rooflight, which sits above the iconic Grade II listed Kiln. To maximise natural light, Howells designed a large 2m x 2m aluminium flat rooflight with double glazing. The glass presented the greatest challenge during installation – having to be craned into position due to its size, weight and intended location.  

The rooflight is fixed to four upstand kerbs that were prepared by others during the reconstruction of the distinctive pyramid roof. It achieves a 1.0 W/m2K U-value and contributes to the building’s thermal performance. The Kiln is now the entrance for commercial tenants.  

Self-supported rooflight  

A further rooflight was specified for the space that connects the adapted Kiln and North Engine House and the existing Cross Mill, installed during Phase 2 of the project. 

Following a site survey by Howells’ draughtsman, Warren Lowe, it was determined that the perimeter flashings were not square, and this needed to be modified before the rooflight could be installed. The existing building was adapted using timber fitted to the eaves. Once remedied, Warren was able to measure the aperture, accurately and design the self-supported rooflight with five degree pitch.  

The rooflight with thermal barrier is constructed from aluminium glazing bars with four panes of glass. It is designed and manufactured in accordance with BS 5516 and BS 1474. Due to the pitch and location of the self-supported rooflight, Howells selected Class 2 non-fragility glazing. This is not designed to be walked upon but is non-fragile and is intended to ensure that, in the event of anyone accidently walking or falling onto the rooflight, they will not fall through it. 

The rooflight was glazed onsite using 28mm double glazed units with a 6mm toughened and Easy Clean outer pane and 9.5mm clear inner pane. Once again, the centre pane achieves a 1.0 W/m2K U-value. Both aluminium rooflights are powder coated in Jet Black. This protective and decorative layer offers exceptional resistance to weathering, corrosion and wear, ensuring longevity and minimal maintenance.  

Shrewsbury Flaxmill Maltings is now open and welcomes visitors to eat, work, visit, learn and enjoy the incredible space. To date, the project has received more than six regional and national RIBA Awards, including RIBA West Midlands Client, Project and Building of the Year 2024. 

www.howellsglazing.co.uk  

Image credit: Daniel Hopkinson