This test method is a standard procedure for determining the resistance to water penetration under uniform or cyclic static air pressure differences of installed exterior windows, skylights, curtain walls, and doors. The air-pressure differences acting across a building envelope vary greatly. These factors should be considered fully prior to specifying the test pressure difference to be used.
Note 18212;In applying the results of tests by this test method, note that the performance of a wall or its components, or both, may be a function of proper installation and adjustment. In service, the performance will also depend on the rigidity of supporting construction and on the resistance of components to deterioration by various causes, vibration, thermal expansion and contraction, and so forth. It is difficult to simulate the identical complex wetting conditions that can be encountered in service, with large wind-blown water drops, increasing water drop impact pressures with increasing wind velocity, and lateral or upward moving air and water. Some designs are more sensitive than others to this upward moving water.
Note 28212;This test method does not identify unobservable liquid water which may penetrate into the test specimen.
Laboratory tests are designed to give an indication of the performance of an assembly. Field performance may vary from laboratory performance since the supporting structure for the test specimen, methods of mounting, and sealing in the laboratory can only simulate the actual conditions that will exist in the building. Shipping, handling, installation, acts of subsequent trades, aging, and other environmental conditions all may have an adverse effect upon the performance of the installed product. This field test procedure provides a means for determining the performance of a product once installed in the building.
The field test may be made at the time the window, skylight, curtain-wall, or door assemblies are initially installed and before the interior of the building is finished. At this time, it is generally easier to check the interior surfaces of the assemblies for water penetration and to identify the points of penetration. The major advantage of testing when assemblies are initially installed is that errors in fabrication or installation can be readily discovered and corrections made before the entire wall with its component assemblies is completed at which time the expense of corrective work may be increased many times.
The field test may also be made after the building is completed and in service to determine whether or not reported leakage problems are due to the failure of the installed assemblies to resist water penetration at the specified static air pressure difference. Generally it is possible to conduct tests on window, skylight, and door assemblies without too much difficulty, and to identify sources of leakage. A curtain-wall assembly, on the other hand, may not be accessible from the inside without the removal of interior finished walls and ceilings. Even with removal of interior walls and ceilings, it may not be possible to observe curtain-wall surfaces behind spandrel beams. The feasibility of conducting a meaningful static air pressure difference water penetration test on an in-service building must be carefully evaluated before being specified.
Weather conditions can affect the static air pressure difference measurements. If wind gusting causes pressure fluctuation to exceed ±10 % from the specified test pressure, the test should not be conducted.
Generally it is more convenient to use an interior mounted pressure chamber from which air is exhausted to obtain a lower pressure on the interior surface of the specimen. A calibrated rack of nozzles is then used to spray.........
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