A new test standard to evaluate the watertightness of window-wall interfaces

Window-wall interfaces must be designed to prevent water ingress caused by all the acting forces: kinetic energy of raindrops, surface tension, gravity action, pressure differences, capillary forces, local air currents and hydrostatic pressure. These connections are the primary areas of concern and an important source of problems in the building enclosure. They are designed by the architect or façade engineer, who is expected to follow the standards, sector documents and technical guidelines offered by the manufacturers. However, despite its importance, there is currently no test standard to assess the weathertightness performance of the installation of the window into the building envelope. Such a standard would not only offer a context for product testing, but also allow the development of more consistent guidelines for building practitioners and manufacturers. Currently available standards only provide testing procedures for the resistance to water penetration for window and door elements (EN 1027, static test sequence), and a generic test protocol for façade systems (EN 12865, cyclic wind pressure sequence). In the framework of a research project for the Belgian Government, an overview of 30 watertightness test standards has been carried out, showing a large variety of approaches, parameters, test pressures, criteria… In this paper a state-of-the-art is presented on the test standards, which propose both laboratory and field procedures, the differences among laboratory standards are highlighted and discussed and the tests results are reported. Subsequently, a proposal is made for a new test standard for window-wall interfaces that balances the needs of the industry (practical constraints, simple and quick) and the requirements from an academic point of view (reliability and repeatability)