In current building practice, the design and construction of roofs with discontinuously laid small elements (roof tiles/slates) are based on practice guidelines derived from years of experience. If these practice guidelines are followed properly, the outcome in many cases is a wellfunctioning roof. Construction damage relating to the waterproofing of this type of structure is usually associated with deviation from the practice guidelines, incorrect details or the use of small roof pitches. In recent decades, more and more solar power systems have been applied to pitched roofs with discontinuously laid small elements. Unfortunately, the very application of solar power systems in combination with discontinuously laid small elements has caused a lot of damage. There is no suitable assessment method. The assessment method advocated within Bouwbesluit 2012 only relates to simple partition constructions and is therefore not suitable for structures referred to within this project that have a pressure equalising layer (air cavity). The assessment method developed within this project allows solar power systems applied to pitched roofs with discontinuously laid small elements to be assessed in terms of waterproofing and compliance with Bouwbesluit 2012. This evaluation method has been harmonised as much as possible with CEN/TR 15601. This was an important starting point because various suppliers of roof tiles and fittings assess their products on the basis of this method, both domestically and throughout Europe. This project involved verifying whether this assessment method is sufficiently in line with the principles of Bouwbesluit 2012; it can be concluded that this is the case and that a difference in pressure, as indicated in the test method, must be assumed. CEN/TR 15601 has been designed such that a test product is validated against a reference product. Within this assessment method, a product/system is assessed in terms of application in the project to be realised; it is region-dependent (Netherlands wind region) and can thus be checked against Bouwbesluit 2012. The assessment method is also suitable for prototype research in order to determine the maximum building height and wind region for which a system can be used. The assessment method consists of: 1. Determining the quantity of water that has penetrated the outer permeable layer in an established (rain and wind) climate; 3. Classifying the quantity of penetrating water; 4. Assessing the inner layer on the basis of the quantity of water that has penetrated the outer layer. The assessment of the outer layer is consistent with CEN/TR 15601, except for the fact that the assessment does not involve a reference model but instead an absolute quantity of penetrating water at a fixed difference in pressure in relation to an applicable project. Definitive values of the quantities of penetrating water must be established on a reference test surface to be determined by the industry. The classification has been designed to be in keeping with the usual roof frame construction methods. This assessment method incorporates a test method for assessing the inner layer, depending on the classification of the outer layer, indicating that the inner layer can also be constructed on the basis of Dutch practice guidelines.
|Date of Award||31 Mar 2013|
|Supervisor||C.P.W. Geurts (Supervisor 1), Bert Blocken (Supervisor 2) & Henk L. Schellen (Supervisor 2)|