More knowledge and realistic data on inward leakage is needed not only to better understand and confirm rain resistance of different facades, but also to carry out reliable theoretical moisture risk assessments of facade details in external walls. This article is an attempt to highlight amounts of expected leakage based on four laboratory studies. The results show that under heavy driving rain conditions, there may be continuous point leakage of significant volumes of water (0,01-0,05 l/min) in small invisible deficiencies, and corresponds to up to 2% of the applied water load. The leakage rate also depends, more or less, on the size, position and geometry of the deficiency, cumulative runoff rates, size of projecting details and surface properties.