Rain Penetration Resistance of Renders-

Norwegian Building Research Institute (NBI) performs experimental investigations in order to assess rain penetration resistance of rendering systems. As a consequence of the increased risk for intense precipitation over parts of coastal Norway in the years to come, a discussion is taking place on how to assess the rain resistance performance of new rendering systems. The intention of this study has been to evaluate whether numerical calculations could fully or partly replace laboratory testing on panels/ constructions, as experimental test programs for constructions are resource consuming. This study indicates that numerical calculations might be a supplement to the experiments. However, numerical calculations cannot replace short time experiments on panels for the time being. The calculations of water absorption didn’t correspond very well with the experimental measurements, mainly due to the sensitivity of water absorption coefficients (A-values). A critical review on determination of water absorption coefficients is given. 1