This test method provides information that aids in evaluating the effect of four principal variables: materials, coatings, wall design, and workmanship.

Water penetration and leakage through masonry is significantly affected by air pressure in the test chamber. Data from tests made at different pressures are not comparable.

The performance of a masonry wall is a function of materials, construction, wall design, and maintenance. In service the performance will also depend on the rigidity of supporting structure and on the resistance of components to deterioration by various causes, such as corrosion, vibration, thermal expansion and contraction, curing, and others. It is impossible to simulate the complex conditions encountered in service, such as variations in wind velocity, negative pressure, and lateral or upward moving air and water. Factors such as location, exposure, and wall openings should be considered.

Given the complexity of variables noted above, this test method establishes comparative behavior between various masonry wall constructions in a given laboratory.

Even when a single laboratory tests the same wall design utilizing the same wall materials and the same construction practices, variables such as the level of skill of the mason building the specimen, the temperature and humidity in the laboratory at the time of construction, curing of the specimen, the moisture contents of the materials used to build the specimen, and even the use or lack of use of a lime and water wash on the back of the specimen can affect the results of the test making reliable comparisons dubious. For these reasons and the multi-variables listed in 4.1, 4.2, and 4.3, a meaningful, useful, absolute wall leakage rating standard is impractical and discouraged.