ASTM D779-16 (2022) PDF

Full title and description

Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method — a short procedural standard that specifies the dry‑indicator technique for measuring the time required for water vapor to pass through sheet membranes when one face is in contact with liquid water, commonly applied to water‑resistive barrier materials and flexible flashings.

Abstract

This test method (designation D779 − 16, reapproved 2022) uses a strongly hygroscopic dry indicator that changes color on exposure to moisture to determine the elapsed time before water vapor penetrates a sheet specimen placed in contact with liquid water. It is intended to provide comparative resistance-to‑vapor‑transmission data for building‑enclosure sheets and related membrane products.

General information

• Status: Published / Active (reapproved 2022).
• Publication date: October 1, 2022 (designation shown as D779‑16 with 2022 reapproval).
• Publisher: ASTM International.
• ICS / categories: ICS 85.060 (Paper and board) — classified under materials and paper/board testing categories in standard catalogs.
• Edition / version: D779‑16 (reapproved 2022).
• Number of pages: 4 pages.

Scope

This method covers determination of the time required for water vapor to pass through a sheet membrane in contact with liquid water using a dry‑indicator (desiccant) that visibly changes when exposed to moisture. It is intended for evaluation of water‑resistive barriers, flexible flashing, and other building‑construction sheet materials where one face may be continuously or intermittently exposed to liquid water. Values are given in inch‑pound units as standard; SI conversions are informational.

Key topics and requirements

• Use of a strongly hygroscopic dry indicator (desiccant) that changes color on moisture exposure to detect vapor penetration.
• Specimen preparation and conditioning per referenced ASTM practices for paper/board and membrane testing.
• Measurement of elapsed time to indication as the primary test result (comparative resistance metric).
• Application to water‑resistive barriers, flexible flashing, and similar sheet materials used in building envelopes.
• Notes on units and safety: inch‑pound units are primary; users must observe necessary laboratory safety and environmental controls.

Typical use and users

Used by materials test laboratories, building‑envelope consultants, membrane and WRB (water‑resistive barrier) manufacturers, quality control teams, and product specifiers to compare vapor‑resistance behavior of sheet products when in contact with liquid water and to inform product selection, R&D, and compliance statements.

Related standards

Often referenced together with ASTM practices and building‑enclosure standards such as conditioning and sampling practices (for example D685), terminology (E631), and other membrane or vapor/permeance specifications (for example E2556 and related envelope test methods); check the standard’s referenced documents section for exact cross‑references.

Keywords

water vapor resistance, dry indicator, desiccant, water‑resistive barrier, flexible flashing, sheet membrane, vapor transmission, hygroscopic indicator.

FAQ

Q: What is this standard?

A: ASTM D779‑16(2022) is a short ASTM test method that prescribes the dry‑indicator procedure to determine how long it takes water vapor to pass through a sheet material when one face is in contact with liquid water.

Q: What does it cover?

A: It covers the test setup, specimen conditioning, use of a hygroscopic dry indicator, and the measurement of elapsed time to visual indication; it is intended for WRBs, flashing, and similar sheet materials used in building construction.

Q: Who typically uses it?

A: Test laboratories, product manufacturers (membranes/flashings), building‑envelope engineers, quality assurance personnel, and specifiers use it for comparative testing and product evaluation.

Q: Is it current or superseded?

A: The designation is D779‑16 with a 2022 reapproval (published/reconfirmed in 2022), so it is current as the reapproved 2016 edition. Users should verify any later revisions directly with ASTM for updates after 2022.

Q: Is it part of a series?

A: It is a standalone ASTM test method but is commonly used alongside other ASTM building‑enclosure and paper/membrane testing practices and specifications; the standard includes references to related ASTM documents.

Q: What are the key keywords?

A: Desiccant, dry indicator, water vapor resistance, water‑resistive barrier, flashing, sheet membrane, vapor transmission.