Rain resistance of façades with façade details: A summary of three field and laboratory studies

One of the main functions of the exterior walls and façades is to protect the indoor and the sensitive parts of construction from the outdoor climate. Exposure of driving rain is the most prominent moisture source a wall has to resist. Despite this, there is a lack of information on rain resistance. Field measurements on real-life external walls show that recurrent water leakage under driving rain conditions is observed in five out of seven new-built houses in Sweden, including those with ventilated façades. About a 100 commercial laboratory façade tests, mounted by façade suppliers, and targeted laboratory experiments showed that it is almost impossible to achieve fully tight façade solutions, and keep them sealed. Nearly, all test walls with façade details leaked, almost regardless of façade type and sealing efforts. The results from field and laboratory measurements of rain resistance in new buildings in Sweden show that façades are usually not water-tight and also that very small deficiencies can cause substantial amount of water leakage.