ASTM C755-10

Standard Practice for Selection of Water Vapor Retarders for Thermal Insulation

SIGNIFICANCE AND USE
Experience has shown that uncontrolled water entry into thermal insulation is the most serious factor causing impaired performance. Water entry into an insulation system may be through diffusion of water vapor, air leakage carrying water vapor, and leakage of surface water. Application specifications for insulation systems that operate below ambient dew-point temperatures should include an adequate vapor retarder system. This may be separate and distinct from the insulation system or may be an integral part of it. For selection of adequate retarder systems to control vapor diffusion, it is necessary to establish acceptable practices and standards.
Vapor Retarder Function—Water entry into an insulation system may be through diffusion of water vapor, air leakage carrying water vapor, and leakage of surface water. The primary function of a vapor retarder is to control movement of diffusing water vapor into or through a permeable insulation system. The vapor retarder system alone is seldom intended to prevent either entry of surface water or air leakage, but it may be considered as a second line of defense.
Vapor Retarder Performance—Design choice of retarders will be affected by thickness of retarder materials, substrate to which applied, the number of joints, available length and width of sheet materials, useful life of the system, and inspection procedures. Each of these factors will have an effect on the retarder system performance and each must be considered and evaluated by the designer.
Although this practice properly places major emphasis on selecting the best vapor retarders, it must be recognized that faulty installation techniques can impair vapor retarder performance. The effectiveness of installation or application techniques in obtaining design water vapor transmission (WVT) performance must be considered in the selection of retarder materials.
As an example of the evaluation required, it may be impractical to specify a lower “as installed” value, ...
SCOPE
1.1 This practice outlines factors to be considered, describes design principles and procedures for water vapor retarder selection, and defines water vapor transmission values appropriate for established criteria. It is intended for the guidance of design engineers in preparing vapor retarder application specifications for control of water vapor flow through thermal insulation. It covers commercial and residential building construction and industrial applications in the service temperature range from −40 to +150°F (−40 to +66°C). Emphasis is placed on the control of moisture penetration by choice of the most suitable components of the system.
1.2 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.
1.3 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.

General Information

• Status: Historical
• Publication Date: 30-Sep-2010
• ICS: 91.120.10 - Thermal insulation of buildings
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.33 - Insulation Finishes and Moisture

Relations

• Replaces: ASTM C755-03 - Standard Practice for Selection of Water Vapor Retarders for Thermal Insulation
• Effective Date: 01-Oct-2010
• Replaced By: ASTM C755-10e1 - Standard Practice for Selection of Water Vapor Retarders for Thermal Insulation
• Effective Date: 01-Oct-2010
• Referred By: ASTM C1127/C1127M-15(2023) - Standard Guide for Use of High Solids Content, Cold Liquid-Applied Elastomeric Waterproofing Membrane with an Integral Wearing Surface
• Effective Date: 01-Oct-2010
• Referred By: ASTM E1677-23 - Standard Specification for Air Barrier (AB) Material or Assemblies for Low-Rise Framed Building Walls
• Effective Date: 01-Oct-2010
• Referred By: ASTM C1015-17 - Standard Practice for Installation of Cellulosic and Mineral Fiber Loose-Fill Thermal Insulation
• Effective Date: 01-Oct-2010
• Referred By: ASTM E631-15 - Standard Terminology of Building Constructions
• Effective Date: 01-Oct-2010
• Referred By: ASTM E241-20 - Standard Guide for Limiting Water-Induced Damage to Buildings
• Effective Date: 01-Oct-2010
• Referred By: ASTM E2112-23 - Standard Practice for Installation of Exterior Windows, Doors and Skylights
• Effective Date: 01-Oct-2010
• Referred By: ASTM E154/E154M-08a(2019) - Standard Test Methods for Water Vapor Retarders Used in Contact with Earth Under Concrete Slabs, on Walls, or as Ground Cover
• Effective Date: 01-Oct-2010
• Referred By: ASTM D7338-14(2023) - Standard Guide for Assessment Of Fungal Growth in Buildings
• Effective Date: 01-Oct-2010
• Referred By: ASTM E2266-22 - Standard Guide for Design and Construction of Low-Rise Frame Building Wall Systems to Resist Water Intrusion
• Effective Date: 01-Oct-2010
• Referred By: ASTM C1320-20 - Standard Practice for Installation of Mineral Fiber Batt and Blanket Thermal Insulation for Light Frame Construction
• Effective Date: 01-Oct-2010
• Referred By: ASTM C1410-17(2023) - Standard Specification for Cellular Melamine Thermal and Sound-Absorbing Insulation
• Effective Date: 01-Oct-2010
• Referred By: ASTM C647-19 - Standard Guide to Properties and Tests of Mastics and Coating Finishes for Thermal Insulation
• Effective Date: 01-Oct-2010
• Referred By: ASTM C991-23 - Standard Specification for Flexible Fibrous Glass Insulation for Metal Buildings
• Effective Date: 01-Oct-2010

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C755 − 10
StandardPractice for
1
Selection of Water Vapor Retarders for Thermal Insulation
This standard is issued under the fixed designation C755; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 Thispracticeoutlinesfactorstobeconsidered,describes 3.1 For definitions of terms used in this practice, refer to
design principles and procedures for water vapor retarder Terminology C168.
selection, and defines water vapor transmission values appro-
4. Significance and Use
priate for established criteria. It is intended for the guidance of
design engineers in preparing vapor retarder application speci-
4.1 Experiencehasshownthatuncontrolledwaterentryinto
fications for control of water vapor flow through thermal
thermal insulation is the most serious factor causing impaired
insulation. It covers commercial and residential building con-
performance. Water entry into an insulation system may be
struction and industrial applications in the service temperature
through diffusion of water vapor, air leakage carrying water
range from−40 to+150°F (−40 to+66°C). Emphasis is placed
vapor, and leakage of surface water.Application specifications
on the control of moisture penetration by choice of the most
for insulation systems that operate below ambient dew-point
suitable components of the system.
temperatures should include an adequate vapor retarder sys-
tem. This may be separate and distinct from the insulation
1.2 The values stated in inch-pound units are to be regarded
system or may be an integral part of it. For selection of
as standard. The values given in parentheses are mathematical
adequate retarder systems to control vapor diffusion, it is
conversions to SI units that are provided for information only
necessary to establish acceptable practices and standards.
and are not considered standard.
1.3 This standard does not purport to address all of the 4.2 Vapor Retarder Function—Water entry into an insula-
safety concerns, if any, associated with its use. It is the tion system may be through diffusion of water vapor, air
responsibility of the user of this standard to establish appro- leakage carrying water vapor, and leakage of surface water.
priate safety and health practices and determine the applica- The primary function of a vapor retarder is to control move-
bility of regulatory limitations prior to use. ment of diffusing water vapor into or through a permeable
insulation system. The vapor retarder system alone is seldom
2. Referenced Documents
intendedtopreventeitherentryofsurfacewaterorairleakage,
2
but it may be considered as a second line of defense.
2.1 ASTM Standards:
C168Terminology Relating to Thermal Insulation
4.3 Vapor Retarder Performance—Design choice of retard-
C647Guide to Properties and Tests of Mastics and Coating
erswillbeaffectedbythicknessofretardermaterials,substrate
Finishes for Thermal Insulation
to which applied, the number of joints, available length and
C921Practice for Determining the Properties of Jacketing
width of sheet materials, useful life of the system, and
Materials for Thermal Insulation
inspectionprocedures.Eachofthesefactorswillhaveaneffect
C1136Specification for Flexible, Low Permeance Vapor
on the retarder system performance and each must be consid-
Retarders for Thermal Insulation
ered and evaluated by the designer.
E96/E96MTest Methods for Water Vapor Transmission of
4.3.1 Althoughthispracticeproperlyplacesmajoremphasis
Materials
onselectingthebestvaporretarders,itmustberecognizedthat
faulty installation techniques can impair vapor retarder perfor-
mance. The effectiveness of installation or application tech-
1
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
niques in obtaining design water vapor transmission (WVT)
Insulation and is the direct responsibility of Subcommittee C16.33 on Insulation
performance must be considered in the selection of retarder
Finishes and Moisture.
materials.
Current edition approved Oct. 1, 2010. Published November 2010. Originally
4.3.2 As an example of the evaluation required, it may be
approved in 1973. Last previous edition approved in 2003 as C755–03. DOI:
10.1520/C0755-10.
impractical to specify a lower “as installed” value, because
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
difficultiesoffieldapplicationoftenwillpreclude“asinstalled”
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
attainment of the inherent WVT values of the vapor retarder
Standards volume information, refer to the standard’s Document Summary page on
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C755–03 Designation: C755 – 10
Standard Practice for
1
Selection of Water Vapor Retarders for Thermal Insulation
This standard is issued under the fixed designation C755; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 Thispracticeoutlinesfactorstobeconsidered,describesdesignprinciplesandproceduresforwatervaporretarderselection,
anddefineswatervaportransmissionvaluesappropriateforestablishedcriteria.Itisintendedfortheguidanceofdesignengineers
in preparing vapor retarder application specifications for control of water vapor flow through thermal insulation. It covers
commercial and residential building construction and industrial applications in the service temperature range from−40 to+150°F
(−40 to+66°C). Emphasis is placed on the control of moisture penetration by choice of the most suitable components of the
system.
1.2
1.2 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.
1.3 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
2
2.1 ASTM Standards:
C168 Terminology Relating to Thermal Insulation
C647 Guide to Properties and Tests of Mastics and Coating Finishes for Thermal Insulation
C921 Practice for Determining the Properties of Jacketing Materials for Thermal Insulation
C1136 Specification for Flexible, Low Permeance Vapor Retarders for Thermal Insulation
E96/E96M Test Methods for Water Vapor Transmission of Materials
3. Terminology
3.1 For definitions of terms used in this practice, refer to Terminology C168.
4. Significance and Use
4.1 Experience has shown that uncontrolled water entry into thermal insulation is the most serious factor causing impaired
performance.Waterentryintoaninsulationsystemmaybethroughdiffusionofwatervapor,airleakagecarryingwatervapor,and
leakage of surface water. Application specifications for insulation systems that operate below ambient dew-point temperatures
should include an adequate vapor retarder system. This may be separate and distinct from the insulation system or may be an
integral part of it. For selection of adequate retarder systems to control vapor diffusion, it is necessary to establish acceptable
practices and standards.
4.2 Vapor Retarder Function—Water entry into an insulation system may be through diffusion of water vapor, air leakage
carrying water vapor, and leakage of surface water. The primary function of a vapor retarder is to control movement of diffusing
water vapor into or through a permeable insulation system. The vapor retarder system alone is seldom intended to prevent either
entry of surface water or air leakage, but it may be considered as a second line of defense.
4.3 Vapor Retarder Performance —Design choice of retarders will be affected by thickness of retarder materials, substrate to
which applied, the number of joints, available length and width of sheet materials, useful life of the system, and inspection
procedures.Eachofthesefactorswillhaveaneffectontheretardersystemperformanceandeachmustbeconsideredandevaluated
by the designer.
1
This practice is under the jurisdiction ofASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.33 on Insulation Finishes
and Moisture.
Current edition approved Nov.Oct. 1, 2003.2010. Published December 2003.November 2010. Originally approved in 1973. Last previous edition approved in 20022003
as C755–023. DOI: 10.1520/C0755-103.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,[e-mail] Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C755 – 10
4.3.1 Although this practice properly places major emphasis on selecting the best vapor retarders, it must be recognized that
fau
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