The pressure difference across a wall assembly arising from the Driving-Rain Wind Pressure (DRWP) produces a driving force that induces water ingress into wall assemblies given the presence of deficiencies on the exterior surface of the wall, and the downward migration of rain water over the wall surface. The extent of water penetration, which has a detrimental effect on the long-term performance of wall assemblies, is affected by the magnitude of the DRWP acting across the wall. In this study, a wall test specimen consists of 3 layers of polycarbonate sheathing has been tested under simulated Wind-Driven Rain (WDR) conditions. Deficiencies of different sizes and configurations were purposely built to the test specimen to investigate the extent of water entry given different DRWPs. To permit investigating the response of water entry under different DRWP conditions, a test protocol having a low cyclic rate was developed such that the water entry rates through the wall deficiencies could be obtained at different magnitudes of DRWP and as well, a variety of cyclic frequencies and amplitudes.