ASTM D779 - 16

    Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method

    Active Standard ASTM D779 | Developed by Subcommittee: E06.55

    Book of Standards Volume: 04.12


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    Significance and Use

    5.1 The dry indicator used in this test method is so strongly hygroscopic it will change color in a moderate- to high-humidity atmosphere without contacting liquid water. It will also change when in contact with liquid water.

    5.2 This test method is of value for materials that come in contact with water on one face and where it is important to evaluate the length of time for water vapor to pass through the material.

    1. Scope

    1.1 This test method covers the determination of the time required for water vapor to pass through a sheet membrane in contact with liquid water using the dry-indicator method.

    1.2 The method has been used to evaluate water resistive barriers, flexible flashing and other materials used in building construction in order to measure their resistance to water vapor transmission.

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

    1.4 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.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D585 Practice for Sampling and Accepting a Single Lot of Paper, Paperboard, Fiberboard, and Related Product

    D685 Practice for Conditioning Paper and Paper Products for Testing

    E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process

    TAPPI Standards

    T 433 Water resistance of sized paper and paperboard (dry indicator method)


    Referencing This Standard
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    DOI: 10.1520/D0779-16

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    Citation Format

    ASTM D779-16, Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method, ASTM International, West Conshohocken, PA, 2016, www.astm.org

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