Steel windows retain profile of listed city school
In 1967, a new building for St Paul's Cathedral Choir School was opened within the cathedral grounds and the choir boys were spared their daily march through ever-increasing London traffic. Forty years later, the original single-glazed aluminium sash windows were falling into dangerous disrepair, so the decision was taken to replace them and Steel Window Service & Supplies Ltd was appointed as the main contractor for this large, demanding project to replace 443 windows and six doors.
Working with Arup Façade Engineering, Steel Window Service & Supplies were not only responsible for supplying the windows and doors; they also looked after health and safety on-site, scaffolding provision and vitally important security measures.
The Choir school is a grade II* listed building, governed by the Twentieth Century Society, with English Heritage also having a major interest. The window replacement contract was subject to strict planning constraints to ensure retention of the school's original look.
The plan was to fit double-glazed windows to reduce noise and improve thermal insulation, but with the additional weight of double glazing, aluminium frames were no longer an option. Only steel frames would be strong enough to retain the fine lines of the original design, so from their range of products, Steel Window Service & Supplies recommended the W40 unit.
To retain the uncluttered building profile created by the sliding sash windows - even when the windows were open - open-out casements were not permitted by Westminster planning authority, and nor was fixing into the outer stonework.
The three panes of the tall, narrow windows were reproduced in the replacement windows, but this time with both the bottom and middle sections fixed. The top pane was bottom hung and opened inwards with the use of an operating pole. The appearance of the original aluminium frames was mimicked using a metallic polyester powder coating and the bottom pane of glass remained opaque. Special fixing lugs were used to secure the frames into the building's internal structure which required removing the plaster.
"We are delighted with the new windows," says Nikki Lovell the school bursar. "The building is much quieter and warmer, and we don't have to worry about the children's fingers anymore!
"After fixing the windows, Steel Window Services redecorated the rooms and were extremely considerate of teachers and pupils, as the school remained open for the duration of the work."
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