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George Wimpey and Co. developed a system of housing using no-fines concrete and traditional construction methods. The concrete without sand has unusual properties in that it can be cast within a mesh or standard formwork and exerts less pressure while mobile than normal concrete. Its porous nature provides some insulating properties although not adequate for today’s requirements. In excess of 300,000 low-rise dwellings from the mid-1940s onwards were built in configurations ranging from bungalows, houses and low-rise blocks of flats of up to 5 storeys.
Before 1951 the external walls were commonly 12” (305mm) thick, whereas between 1951 and 1964 this reduced to 10” (250mm). After 1964 the external walls were commonly 8” (200mm) thick. As a general method, a band of reinforcement bar was incorporated in dense insitu concrete at eaves level. Support above ground floor door and window openings is provided by precast lintels with projecting reinforcement, although before 1951 only reinforcement bar was used. The load bearing internal walls were sometimes masonry or timber rather than no-fines. The no-fines sometimes formed the inner leaf of a masonry-faced cavity construction. Rendering was applied in two or more coats to the external face depending on the exposure conditions. Internally the walls were dry-lined or hard plaster. The party walls were sometimes rendered to reduce sound transmission.
Acknowledgement: The Concrete Society
Other references:The structural condition of Wimpey no-fines low-rise dwellings. BRE Report 153, 1989.
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