Renovation of this 12,500 m2, stylistically typical mid–twentieth century civic building began in 2009 and will be completed in 2012, covering interiors as well as external brick and copper facades. Technically, there was nothing wrong with the original copper but moisture ingress and a lack of thermal insulation created problems over the decades. Extensive renovation was started by erecting scaffolding and ‘shrink-wrapping’ the exterior walls, after which the old structure was removed and stored inside the building. Around 50 tons of copper and 5.5 tons of brass were stripped and taken back to the original supplier. The window openings were sealed throughout the dismantling process. The drawn trim on the façade had previously been brass, but this was replaced with copper instead. The thermo element bars were then fitted and, once the new windows had been installed, 50 +150 mm mineral wool insulation and wind shield boards were fixed to the walls. A stainless steel ‘hat’ profile was fastened to the thermo elements and the copper was laid onto a substrate of impregnated crosswise boarding. After these preparations, installation of copper onto the exterior walls could be started: this took a full year.
Reinstating the Original Design
A sample for the new cassettes and drawn trim was taken from the dismantled façade and followed faithfully in the new work. Pre-oxidised copper giving a warm shade of light brown was used throughout. The copper was taken to the works in coils, sheets and drawn trim, and worked into profiles. The profiles were about 800–2300 mm long and 290–900 mm high with a thickness of 0.6 mm and the bottom layer 0.8 mm thick. Copper has been re-used here in a versatile way – from cornice to foundation. The façades now consist of the original brick wall, contrasting with profiled copper panels and protruding pilasters. In addition, window frames and details are copper-clad. Some 70 tons of copper has been installed on the new façade and most of the raw material was recycled copper stripped from the building. Major savings resulted from this process – both in financial and environmental terms. This is a clear demonstration of the low ‘whole life cost’ and embodied energy or carbon footprint of copper in architecture.
Original Architects: Risto-Veikko Luukkonen and Helmer Steenroos
Reinstatement Copper Installer: Hartela Oy
Copper product: Nordic BrownTM Light
Photos: Kalle Luoma