Gigla, Birger1
1 Prof. Dr.-Ing., Full Professor, University of Applied Sciences Lübeck, Germany, gigla@fh-luebeck.de
ABSTRACT
The resistance of masonry veneer walls against rain penetration has been a design issue since centuries. Different local construction details have been developed in affected regions with rainy winters and periodically high wind days, including coastal areas of the United States, Canada, Northern Europe and Australia. Scientifically, two aspects have to be investigated: The rain penetration and the properties of the exterior wall surface. The design rain load on walls depends on local weather conditions, rain impact characteristics (e. g. duration and distribution), height of the building and the topography surrounding the building. In the case of masonry veneer walls main properties of the exterior wall surface are the quality of the joints and the capillarity of the bricks. With a lack of knowledge of relevant wall surface parameters and uncertainties in the characteristic rainfall duration, it is not possible to assess the influence of rain penetration through hygrothermal simulations. Another relevant factor of the resistance of masonry veneer walls against rain penetration is the fitting of windows and door-openings. Additionally, concepts of “barrier-free” or “universal” constructions have to be considered. “Smooth” door openings and floor level windows require adequate construction details for the rain protection of veneers. The paper describes laboratory tests investigating the resistance of masonry veneer walls with windows against rain penetration. Eight specimen with four different flashing-systems between facing wall and backing wall have been tested under laboratory rain exposure. Based on the results, detailing recommendations are given. The assessed water absorption is compared with the recommendations of the ASHRAE Standard 160, that are also applied in hygrothermal simulation models.
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