In order to evaluate wall components, various tests can be utilized. Methods for the evaluation of these components are outlined in ASTM E 2128, Evaluating Water Leakage of Building Walls. One of the methods described in this standard involves directing water in a targeted fashion by building a dam around suspect areas and applying water. Hydrostatic head pressure comes into play only if the water is retained at some level in the dam. However, when water exits the dam as fast as it is poured into the dam, then hydrostatic pressure is not necessary for water to enter the components, mere capillary conduction is all that is necessary and the dam acts then more as a funnel, isolating water to specific areas. The benefit of the approach is that it is more precise as to the locations where the defect lies. This helps with the inference of the results when comparing the test locations to section details.
In the video, this targeted approach is being used to apply water to window frame components. The mulling has an internal weep system on the window, employing vents at the top, bottom, and sides of the mulled frame where water can exit after infiltrating behind the mull components. The test was run with equalized pressure between the inside and outside, and repeated with a small amount of differential negative pressure applied to the interior. When pressure was added, water within the weep system of the window infiltrated to the building interior and migrated to damaged areas. The leaks replicated the observations during rain events. The pressure used was also consistent with the rain events, when comparing the stagnation pressure to wind velocity on days when the windows leaked. The interfaces where a defect must exist are narrowed down to a few inches, making it easy to determine where missing or damaged seals should be looked for in the window frame.
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