Improvement of the water resistancy in the integration of photovoltaic panels on traditional roofs

Traditional stone roofs had been used in western alpine area for centuries, and they still characterize the identity of the local environment. Actual use of historical housing requests them to be as efficient as modern one, why ancient roofs are often replaced with new coverings, realized with modern products and materials (i.e. small industrial elements, such as tiles). The paper describes the water tightness of roof coverings and illustrates the principal constructive elements which influence the behaviour of traditional stone roofing. The report discusses the results of wind driven rain experimental tests carried out by means of a closed wind tunnel on stone roofs made of gneiss slates, built diagonally according to a traditional technique which is very common at the moment in the area taken into consideration. Particular attention is paid to the project criteria and construction techniques which can easily be applied to improve the water tightness. If such criteria and techniques were adopted, they could enable stone roofs to be as efficient as modern roof coverings made of small industrial elements (e.g. tiles).