【国外标准】 Standard Practice for Use of Test Methods for Determining the Water Vapor Transmission (WVT) of Exterior Insulation and Finish Systems (EIFS)

5.1 The purpose of this test is to obtain steady state values of water vapor transfer through the EIFS sample. This characteristic of EIFS is commonly requested by regulatory and design organizations, and is used in thermal and moisture studies of building walls. The degree to which an EIFS allows water vapor to pass through it can affect the performance of an EIFS wall assembly.5.2 A permeance value obtained under one set of test conditions does not indicate the value under a different set of conditions. For this reason, the test conditions selected are those that most closely approach the conditions of use for EIFS components and assemblies.5.3 This standard should not be used alone as the sole means for evaluating the water vapor transmission characteristics of a given EIFS wall assembly. Other methods are available, and should be considered and used as appropriate.5.4 To be meaningful in evaluating the thermal and moisture condition of a given EIFS wall assembly, the specimens used in this standard should represent closely the materials that actually exist, or will exist, on a given building.1.1 This practice describes how to use Test Methods E96/E96M to determine the water vapor transmission (WVT) characteristics of an EIFS sample.1.2 An Exterior Insulation and Finish System (EIFS) is a multilayer exterior building wall material that consists of a number of layers. For the purpose of this standard, these layers, whether they be individual EIFS component materials in single layers, or groups of EIFS component materials, are called the “EIFS sample.”1.3 The Water Method, Procedures B and D described in X1.1.2 and X1.1.5 of Appendix X1 of Test Methods E96/E96M shall be used in this practice.1.4 This practice is limited to specimens not over 11/4 in. (32 mm) in thickness, except as provided in Section 9 of this practice.1.5 The values stated in inch-pound units are to be regarded as the standard. Metric inch-pound conversion factors for water vapor transmission, permeance, and permeability are stated in Table 1 of Test Methods E96/E96M. All conversions of mm Hg to Pa are made at a temperature of 0 °C.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.