Materials less than or equal to 15.0 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.

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 without changing the original character of the materials. If a product cannot be cut without changing the original character of the material, the test report shall contain an appropriate note to this effect. Results shall be reported on the basis of equal nominal wetted specimen surface area (in units of kilograms per square metre) 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 thickness. If a product cannot be cut to a thickness of 25.4 mm or if the actual product thickness is less than 25.4 mm but greater than 15.0 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.

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 may depend on the nominal wetted surface area available for water intake.

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 may depend on the volume of the specimen available for water intake.

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 may contribute to fungal growth), localized collection of electrolytes (that may contribute to corrosion), etc. Depending on the primary performance characteristic that is of interest, the preferred units for use in comparing the water retention of different materials may be either kilograms per square metre or percent by volume.

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

The water retention characteristics of materials may 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 that may be 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, may not be directly comparable. Also, test results for specimens of different thickness may not be directly comparable because of porosity effects. The surface characteristics of a material also affect drainage. Specimens with rough surfaces may retain more surface water than specimens with smooth surfaces, and surface treatment during specimen preparation may affect water intake and retention. Therefore, results for materials with different surface characteristics may not be directly comparable.

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, the test results may be misleading.

1.5 The values stated in SI units are to be regarded as standard, but the results may also be reported in inch-pound (I-P) units. In this standard I-P units are given in parentheses for information purposes and may be approximate.

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 and health practices and determine the applicability of regulatory limitations prior to use.