The most commonly-used standard method of testing a masonry wall's leakage performance in the laboratory is the ASTM Standard Test Method for Water Penetration and Leakage Through Masonry (C 1389) water chamber test. The apparatus from this test has been modified for field use by various individuals but no standard provisions for field use have yet been developed. ASTM is currently considering such a standard test method for field water chamber testing. The purpose, interpretation of results, significance, and procedures of the field test have been questioned and criticized in the past. It is the purpose of this paper to address wind-driven rainfall simulation using the chamber test in the field or laboratory.
Water intrusion into and through a masonry facade is affected by air pressure, momentum, gravity, capillary action, and other basic scientific principles. Analysis of the driving forces behind water penetration is presented to show the relationship between these phenomena and testing variables.
Water testing may be designed to simulate wind-driven rainfall. It is therefore appropriate that the parameters of testing be varied, depending upon the realistic weather conditions of the geographical area in which the test is being conducted. Or, if a “standard” set of conditions is used, an analysis of local weather data should be made so that a statement of severity can be given. The use of site-specific or area-specific weather data can provide information for more accurate storm simulation when testing the water resistance of a particular wall. This paper discusses the various types of data available for selection of parameters for water chamber testing. Emphasis is placed on more realistic testing so that more meaningful results may be obtained. Classic parameters, such as the Driving Rain Index, local rainfall intensity, time of concentration, recurrence period, and similar wind storm statistics as well as real-time data from weather stations, are examined for adaptation to this test method.
Through the use of the concepts and procedures presented in this paper, a more thorough understanding of realistic water testing of masonry structures and a more accurate determination of a building's performance with regard to water penetration using the water chamber test method will be available.