Results from laboratory tests of wind driven rain tightness in more than 100 facades and weather barriers

Paper in proceeding, 2014

Over the past five years SP Technical Research Institute of Sweden have, for our clients, made more than one hundred wind driven rain tests in the laboratory of mock-ups of rendered stud walls or ETICS (External thermal insulation composite system) of existing and new designs and other types of facades and weather barriers. More than 90 % of all tested objects failed and nearly 50 % of all details failed. Connections to windows got the worst results overall, despite windows being the most common details in facades. It is difficult to achieve good results in ETICS or undrained facades and even ventilated facades despite venting create pressure equalization across the façade. The weather barrier would be particularly
important for the facades of multi-storey buildings, as leakages are added together downwards. If there are also flaws in the weather barrier there is an increased risk of leakage within the structure. Results from the tests of the weather barriers exposed to rain are similar to conclusions derived for facades. The consequence of leakage through the façade and to the structure has not been included in this study.

One can rarely visually determine whether façade detail solutions are rain tight before the test. It is hardly possible to determine the rain tightness of details only by theoretical assessment of drawings.