RETROFIT WITH INTEGRITY: ASWS ENHANCES FENESTRATION AT SHOREDITCH LANDMARK
Associated Steel Window Services( ASWS) played a pivotal role in the transformation of The Harrison( formerly Curtain House), a Grade II listed 19th-century building in Shoreditch, London, into 40,000 sq ft of high-specification office space. The specialist contractor was responsible for the restoration, refurbishment and replacement of steel and timber fenestration throughout the project, helping to deliver modern standards of performance while preserving the building’ s historic character.
As an acknowledged expert in steel and timber window repair and replacement, ASWS was awarded four separate fenestration packages, alongside additional works, during the two-year redevelopment led by Red Construction for Aviva’ s Climate Transition Fund. Designed by project architect Anomaly, the scheme targeted BREEAM Excellent and an EPC rating of‘ A’, making the upgrading of the building’ s fenestration a critical element of the project’ s success.
The seven-storey former furniture warehouse has been reimagined as flexible office accommodation spread across five floors. According to ASWS Operations Director Kris Bennell, the company’ s ability to deliver all fenestration elements under one contract was a key factor in its appointment.
“ We were asked to cost replacement and refurbishment packages for both timber and steel windows, and were successful across all tenders,” he said.“ Our proposal offered the benefit of one specialist contractor and one manager overseeing all fenestration works, ensuring continuity of finish and programme efficiency.”
Initially, replacement of timber windows within one of the building’ s lightwells was planned, but this strategy evolved into refurbishment following detailed inspection. Around a dozen windows required new timber sections to be spliced in where rot was extensive, while others were repaired using ASWS’ s resin repair techniques. New glazing bars were fitted, windows were reglazed, and opening vents overhauled and draught-proofed.
Further challenges emerged once scaffolding was erected, revealing timber sub-frames in poor condition. In several cases, entire sills required replacement. However, as the steel frames could not be removed, ASWS developed a bespoke solution, milling new subframes into three slim sections that could be inserted through narrow openings and fixed in situ, while accurately matching the original profiles.
The steel windows, many of which were Mid Universal sections, also required extensive repair. Where corrosion was severe, new steel sections were welded in, fabricated from steel plate as the original profiles are no longer available. All original ironmongery was carefully removed, stripped, polished and lacquered before refitting as part of the final works.
ASWS also undertook extensive internal fenestration works, including refurbishment of timber and steel windows and the reglazing of nearly 350 panes of glass. Authentic putty glazing was used throughout, requiring close coordination with decorating contractors to allow sufficient curing time. In selected retained windows, thermal performance was enhanced through the installation of slimline 4-4-4 insulating glass units, achieving a centre pane U-value of 2.6 W / m ² K compared to 6.4 W / m ² K for single glazing. Narrow 7mm warm-edge spacer bars ensured the upgrades remained visually discreet.
Additional challenges arose from the building’ s change of use. New washrooms were installed in front of existing windows, which risked exposing services to external view. ASWS resolved this by installing internal glazing films to black out the affected panes while retaining the external appearance.
Senior Project Manager at Red Construction, Matt Coleman, praised ASWS’ s contribution, highlighting the team’ s expertise, flexibility and high standards of finish. Project architect Henry Dunford-Baker of Anomaly added that improvements to U-values and airtightness were instrumental in achieving the project’ s sustainability targets, while on-site restoration preserved the building’ s original character.
Summing up, Bennell described The Harrison as“ an exemplar of how to approach heritage retrofit,” demonstrating how careful restoration, combined with modern performance upgrades, can futureproof historic buildings without compromising their identity.
ASWS offers a full range of survey, repair, replica replacement and maintenance services for all ages and types of metal and timber windows. For more information on ASWS, please visit www. asws. co. uk.
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