2-879-232 - Historic England Archive/Heritage Images

Construction of a multi-storey block of 'Sectra' flats in Manchester, 09/07/1963. Looking up at a worker ascending a concrete staircase during the construction of a multi-storey block of 'Sectra' flats in Manchester. 'Sectra’ was a French prefabricated steel formwork design for flats which John Laing and Son Ltd acquired the British rights to in 1962. It was a method of using precision made steel formwork for the placing of structural concrete in 'tunnel' sections in room unit widths and ceiling heights. The units were bolted together in rows on special tracks, with the concrete poured to form the walls and floors in one operation. The formwork was internally heated to accelerate the hardening of the concrete in the mould and the sections were then lifted into position by a tower crane on the construction site.