4.1 Materials less than or equal to 15 mm (0.59 in.) in thickness shall not be tested in accordance with this test method in order to avoid complete immersion of the specimens. This type of exposure is beyond the scope of this test method.

4.2 This test method is used to assess both the short-term water retention and the long-term water retention. The short-term water retention is assessed as the average of the water retained following partial immersion intervals of 0.75-h and 3.00-h, in kilograms per square meter (percent by volume) (for materials tested at 25.4 mm (1.00 in.) thickness). The long-term water retention is assessed as the water retained following a 168-h partial immersion interval, in kilograms per square meter (percent by volume) (for materials tested at 25.4 mm (1.00 in.) thickness).

4.3 Materials shall be tested at both actual product thickness and 25.4 mm (1.00 in.) thickness provided the materials can be cut to a thickness of 25.4 mm (1.00 in.) without changing the original character of the materials. If a product cannot be cut without changing the original character of the material, the corresponding information shall be provided in the test report. Results shall be reported on the basis of equal nominal wetted specimen surface area (in units of kilograms per square meter) for materials tested at actual product thickness and on the basis of equal specimen volume (in units of percent by volume) for materials tested at 25.4 mm (1.00 in.) thickness. If a product cannot be cut to a thickness of 25.4 mm (1.00 in.) or if the actual product thickness is less than 25.4 mm (1.00 in.) but greater than 15 mm (0.59 in.), the product shall only be tested at actual product thickness and results only reported on the basis of equal nominal wetted specimen surface area.

4.3.1 By reporting results on the basis of equal nominal wetted specimen surface area, specimens of different thicknesses can be compared equitably. For some specimens, the water intake and retention primarily depends on the nominal wetted surface area available for water intake.

4.3.2 By reporting results on the basis of equal specimen volume, specimens can be compared equitably using units that commonly are selected to represent results of water intake testing (percent by volume). For some materials, water intake and retention primarily depends on the volume of the specimen available for water intake.

4.3.3 In most cases water retention is a secondary performance characteristic that has an influence on a primary performance characteristic, such as thermal performance, surface accumulation of moisture (that will potentially contribute to fungal growth), or localized collection of electrolytes (that will potentially contribute to corrosion). Depending on the primary performance characteristic that is of interest, the preferred units for use in comparing the water retention of different materials will be either kilograms per square meter or percent by volume.

4.4 Immersion times in addition to those required by this test method shall be permitted to be selected provided that all parties involved are in agreement.

4.5 The water retention characteristics of materials will potentially be affected by conditions such as elevated temperatures or chemical exposures.

1.1 This test method determines the amount of water retained (including surface water) by rigid block and board thermal insulations used in building construction applications after these materials have been partially immersed in liquid water for prescribed time intervals under isothermal conditions. This test method is intended to be used for the characterization of materials in the laboratory. It is not intended to simulate any particular environmental condition potentially encountered in building construction applications.

1.2 This test method does not address all the possible mechanisms of water intake and retention and related phenomena for rigid thermal insulations. It relates only to those conditions outlined in 1.1. Determination of moisture accumulation in thermal insulations due to complete immersion, water vapor transmission, internal condensation, freeze-thaw cycling, or a combination of these effects requires different test procedures.

1.3 Each partial immersion interval is followed by a brief free-drainage period. This test method does not address or attempt to quantify the drainage characteristics of materials. Therefore, results for materials with different internal structure and porosity, such as cellular materials and fibrous materials, are not necessarily directly comparable. Also, test results for specimens of different thickness are not necessarily directly comparable because of porosity effects. The surface characteristics of a material also affect drainage. It is possible that specimens with rough surfaces will retain more surface water than specimens with smooth surfaces, and that surface treatment during specimen preparation will affect water intake and retention. Therefore, it is not advisable to directly compare results for materials with different surface characteristics.

1.4 For most materials the size of the test specimens is small compared with the size of the products actually installed in the field. If the surface-to-volume ratios for the test specimens and the corresponding products are different, it is possible that the test results will be misleading.

1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

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.