ASTM C1878-19

Standard Test Method for Surface Water Resistance of Vapor Retarders for Thermal Insulation

SIGNIFICANCE AND USE
3.1 Vapor retarders used on thermal insulation can be exposed to liquid water in normal usage. Some cannot tolerate such exposure without suffering damage. Others are designed to withstand intermittent or occasional exposure in their intended indoor usage. Still others are intended for outdoor applications and exposure to the elements. (not covered by this standard).  
3.2 This test is used to evaluate products or materials that are used where exposure to liquid water on the surfaces on an intermittent or occasional basis is possible. Such products would be expected to absorb very little water, if any, in this test.  
3.3 In the test, the specimen is exposed to a specified volume of water over a given exposure area, with a resultant head pressure.  
3.4 The amount of water absorbed by a specimen is measured in this test. This is used to characterize the water resistance of the specimen. The less water absorbed, the more water resistant the surface is considered to be.
SCOPE
1.1 This test method details a procedure for the determination of the surface water resistance of a vapor retarder by measurement of the quantity of water absorbed in a specified time by the service-exposed surface of a vapor retarder intended for use on thermal insulation.  
1.2 This test method covers vapor retarders that are expected to withstand intermittent or occasional exposure to liquid water on the exposed side. Examples of this exposure are condensation and light rain during installation before a structure is enclosed.  
1.3 This method does not cover vapor retarders intended for exposure to the elements in outdoor applications.  
1.4 This method does not cover thermal insulation products that also act as vapor retarders, such as elastomeric foam and cellular glass.  
1.5 In the test, the specimen is exposed to a specified volume of water over a given exposure area, with a resultant head pressure.  
1.6 The test method is based on Test Method D3285 (withdrawn), the so-called “Cobb” test used for paper.  
1.7 The values stated in SI units are to be regarded as standard.  
1.8 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.  
1.9 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.

General Information

• Status: Published
• Publication Date: 31-Mar-2019
• ICS: 91.100.50 - Binders. Sealing materials
• ICS: 91.120.30 - Waterproofing
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.33 - Insulation Finishes and Moisture

Relations

• Referred By: ASTM C1136-23 - Standard Specification for Flexible, Low Permeance Vapor Retarders for Thermal Insulation
• Effective Date: 01-Apr-2019

Overview

ASTM C1878-19: Standard Test Method for Surface Water Resistance of Vapor Retarders for Thermal Insulation details a reliable procedure for evaluating how well vapor retarders resist surface water absorption. Vapor retarders are crucial components for protecting thermal insulation in buildings and industrial applications. Ensuring that these materials can withstand incidental or occasional contact with liquid water is essential for maintaining the insulation's performance and integrity over time.

This test method is designed for vapor retarders used indoors or during installation, where exposure to condensation or light rain, before a structure is fully enclosed, may occur. The standard provides a basis for measuring the water absorbed by the exposed surface of vapor retarder materials, helping users verify the surface water resistance capabilities of their products.

Key Topics

• Surface Water Resistance: The main focus is to determine how much water the exposed surface of a vapor retarder absorbs during controlled testing, indicating the product’s suitability for its intended use.
• Applicability: The test method applies to vapor retarders expected to encounter occasional or intermittent water exposure, not continuous or outdoor exposure to the elements.
• Exclusions: Does not cover vapor retarder-insulation composites (like elastomeric foam or cellular glass) or vapor retarders meant for outdoor use.
• Test Procedure:
  • A specimen is exposed to a calibrated amount of water over a given area.
  • Head pressure is applied for a specified period.
  • Water absorption is measured by weighing the specimen before and after exposure.
• Basis: The method is derived from the “Cobb” test (ASTM D3285), historically used for measuring water resistance in nonfibrous paper.
• Reporting Requirements: Reports should specify the specimen’s tested side and the measured water absorption.

Applications

ASTM C1878-19 finds broad practical application across sectors involved in building and construction, insulation manufacturing, and product quality control:

• Building Envelope Protection: Ensures vapor retarders maintain barrier performance during intermittent water exposure, such as condensation in attics or light rain during installation.
• Quality Assurance: Manufacturers can use this method to certify material performance, helping customers select products that reduce the risk of insulation degradation due to water ingress.
• Specification Compliance: Architects, designers, and builders can reference ASTM C1878-19 to specify vapor retarders meeting minimum requirements for surface water resistance in moisture-prone environments.
• R&D and Product Development: Enables comparative evaluation of materials and supports innovation in water-resistant vapor retarder technology.

Using a standardized water resistance test helps ensure that vapor retarders perform as intended, reducing repair costs and extending the service life of insulation systems.

Related Standards

• ASTM D3285: Test Method for Water Absorptiveness of Nonbibulous Paper (Cobb Test) - foundation for developing C1878-19, now withdrawn.
• ASTM C16: Committee on Thermal Insulation, overseeing performance standards for insulation-related products.
• Building Codes/Regulations: ASTM C1878-19 may be referenced in specifications and local or international building codes concerning moisture management and insulation performance.

Keywords: surface water resistance, vapor retarder, thermal insulation, ASTM C1878-19, Cobb test, moisture protection, water absorptiveness, building envelope, insulation quality, indoor applications.

Standards Content (Sample)

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.
Designation: C1878 − 19
Standard Test Method for
Surface Water Resistance of Vapor Retarders for Thermal
Insulation
This standard is issued under the fixed designation C1878; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method details a procedure for the determina- 2.1 ASTM Standards:
tion of the surface water resistance of a vapor retarder by D3285 Test Method for Water Absorptiveness of Nonbibu-
measurement of the quantity of water absorbed in a specified lous Paper and Paperboard (Cobb Test) (Withdrawn
time by the service-exposed surface of a vapor retarder 2010)
intended for use on thermal insulation.
3. Significance and Use
1.2 This test method covers vapor retarders that are ex-
pected to withstand intermittent or occasional exposure to 3.1 Vapor retarders used on thermal insulation can be
exposed to liquid water in normal usage. Some cannot tolerate
liquidwaterontheexposedside.Examplesofthisexposureare
such exposure without suffering damage. Others are designed
condensation and light rain during installation before a struc-
to withstand intermittent or occasional exposure in their
ture is enclosed.
intended indoor usage. Still others are intended for outdoor
1.3 This method does not cover vapor retarders intended for
applications and exposure to the elements. (not covered by this
exposure to the elements in outdoor applications.
standard).
1.4 This method does not cover thermal insulation products
3.2 This test is used to evaluate products or materials that
that also act as vapor retarders, such as elastomeric foam and
are used where exposure to liquid water on the surfaces on an
cellular glass.
intermittent or occasional basis is possible. Such products
1.5 In the test, the specimen is exposed to a specified
would be expected to absorb very little water, if any, in this
volume of water over a given exposure area, with a resultant
test.
head pressure.
3.3 In the test, the specimen is exposed to a specified
1.6 The test method is based on Test Method D3285
volume of water over a given exposure area, with a resultant
(withdrawn), the so-called “Cobb” test used for paper.
head pressure.
1.7 The values stated in SI units are to be regarded as
3.4 The amount of water absorbed by a specimen is mea-
standard.
sured in this test. This is used to characterize the water
1.8 This standard does not purport to address all of the resistance of the specimen. The less water absorbed, the more
safety concerns, if any, associated with its use. It is the water resistant the surface is considered to be.
responsibility of the user of this standard to establish appro-
4. Apparatus
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 Water Absorption Apparatus, to permit one side of the
1.9 This international standard was developed in accor-
specimen to be wetted uniformly at the moment the soaking
dance with internationally recognized principles on standard-
period begins, and to allow controlled rapid removal of the
ization established in the Decision on Principles for the
water from the specimen at the end of the test period.
Development of International Standards, Guides and Recom-
4.1.1 A specimen holder as shown in Fig. 1 comprised of a
mendations issued by the World Trade Organization Technical
metal ring with a machined lower face, 11.28 6 0.02 cm inside
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction ofASTM CommitteeC16 on Thermal contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Insulation and is the direct responsibility of Subcommittee C16.33 on Insulation Standards volume information, refer to the standard’s Document Summary page on
Finishes and Moisture. the ASTM website.
Current edition approved April 1, 2019. Published May 2019. DOI: 10.1520/ The last approved version of this historical standard is referenced on
C1878-19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1878 − 19
FIG. 1 Water Absorption Apparatus
diameter (creating a tested area of 100 cm ), 2.5 cm high and 7.3 Place a dry rubber mat on the metal plate and lay a
about 0.6 cm thick (A in photo).
weighed specimen on it, service-exposed side up.After wiping
4.1.2 A ring, is clamped to a flat base plate (B in photo) the metal ring perfectly dry, place it upon the specimen, and
about 15 by 15 cm with a metal cross bar 17 by 2.5 by 0.6 cm
fastenitfirmlyenoughinplacewiththecrossbartopreventany
and two wing nuts
...