My client was adding lightweight steel-framed pitched roofs above existing flat roofs in blocks of 3-4 storey residential flat/maisonettes as part of an upgrade. The client considered that it did not need to provide cavity barriers at every party wall location, and had appealed to the local building control authority. ADB Volume 2 recommends that the separating elements of adjoining flats possess a one hour fire resistance according to BS 476, and with most timber-joisted roof construction this would mean ...
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