Safety against formation of through cracks of profiled fibre-reinforced cement sheets for roofing

Loads due to wind, snow or traffic on a roof determine the requirements to the strength and stiffness properties of profiled sheets for roofing. Apart from these loads, locked-in stresses can occur due to differences in temperature and moisture strains in the profiled sheets and the wooden laths supporting the sheets. These tensile and compressive stresses are induced in the sheets if they are firmly fastened to the laths with fastening screws.The purpose of this investigation was to analyse the safety of the profiled sheets in transmitting these loads without the formation of through cracks.The analysis is based on an experimental and a theoretical investigation of the strength and stiffness properties of unexposed profiled fibre-reinforced cement sheets and of sheets that had been exposed on a roof in three years.