Reports tests made to examine moisture problems in a flat roof of cold deck construction. Tests simulated the effect of normal, wet and very wet conditions below the roof with no ventilation of the roof. Found that without ventilation there is a substantial risk of moisture degrade and condensation problems. Roof was then ventilated at five air changes per hour and this was found to be effective in solving moisture problems. Suggests this as a minimum ventilation rate and that where it is difficult to provide ventilation in a flat roof, a warm deck design should be considered.
Reviews the requirement in building regulations for cavity barriers in roofs. States need for providing ventilation in the cavities of certain forms of roof construction,particularly those with a continuous waterproof vapour barrier to avoid moisture build-up. Examines how adequate air movement can be provided in both new and existing flat roof voids, designed with or having installed cavity barriers.
Describes measurement of wind pressures on low-rise buildings at Aylesbury. Pressures were recorded simultaneously at over one hundred positions divided between seven houses in an estate and a specially constructed building situated on open ground adjoining the state. The roof pitch of the experimental building could be quickly varied to any angle between 5 and 45 deg. and this was used to investigate the variation of pressure distributions over the surfaces of the building. Data are presented for two skew wind directions. Initial comparisons are made with wind-tunnel tests.
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