ASTM C1373/C1373M-23
(Practice)Standard Practice for Determination of Thermal Resistance of Attic Insulation Systems Under Simulated Winter Conditions
Standard Practice for Determination of Thermal Resistance of Attic Insulation Systems Under Simulated Winter Conditions
SIGNIFICANCE AND USE
4.1 The thermal resistance of a ceiling system is used to characterize its steady-state thermal performance.
4.2 The thermal resistance of insulation is related to the density and thickness of the insulation. Test data on thermal resistance are obtained at a thickness and density representative of the end use applications. In addition, the thermal resistance of the insulation system will be different from that of the thermal insulation alone because of the system construction and materials.
4.3 This practice is needed because the in-service thermal resistance of some permeable attic insulations under winter conditions is different, lower or higher R, than that measured at or close to simulated room temperature conditions utilizing small-scale tests in which the insulation is sandwiched between two isothermal impermeable plates that have a temperature difference (ΔT) of 20 to 30°C [36 to 54°F]. When such insulation is installed in an attic, on top of a ceiling composed of normal building materials such as gypsum board or plywood, with an open top surface exposed to the attic air space, the thermal resistance under winter conditions with heat flow up and large temperature differences is significantly less because of additional heat transfer by natural convection. Fig. 1 illustrates the difference between results from small scale tests and tests under the conditions of this practice. See Ref (1-12) for discussions of this phenomenon.3
FIG. 1 Schematic of Thermal Resistance for a Permeable Attic Insulation Under Simulated Winter Conditions (Heat Flow Up)
Note 1: A constant hot-side temperature (T, hot) is used for both tests and the temperature difference increases as the cold side temperature (T, cold) is decreased. See 5.1.6 for requirements on size of air space.
4.4 In normal use, the thickness of insulation products ranges from 75 mm [3 in.] to 500 mm [20 in.]. Installed densities will depend upon the product type, the installed thickness, the installa...
SCOPE
1.1 This practice presents a laboratory procedure to determine the thermal resistance of attic insulation systems under simulated steady-state winter conditions. The practice applies only to attic insulation systems that face an open attic air space.
1.2 The thermal resistance of the insulation is inferred from calculations based on measurements on a ceiling system consisting of components consistent with the system being studied. For example, such a system might consist of a gypsum board or plywood ceiling, wood ceiling joists, and attic insulation with its top exposed to an open air space. The temperature applied to the gypsum board or plywood shall be in the range of 18 to 24°C [64 to 75°F]. The air temperature above the insulation shall correspond to winter conditions and ranges from –46°C to 10°C [–51 to 50°F]. The gypsum board or plywood ceiling shall be sealed to prevent direct airflow between the warm and cold sides of the system.
1.3 This practice applies to a wide variety of loose-fill or blanket thermal insulation products including fibrous glass, rock/slag wool, or cellulosic fiber materials; granular types including vermiculite and perlite; pelletized products; and any other insulation material that is installed pneumatically or poured in place. The practice considers the effects on heat transfer of structures, specifically the ceiling joists, substrate, for example, gypsum board, air films, and possible facings, films, or other materials that are used in conjunction with the insulation.
1.4 This practice measures the thermal resistance of the attic/ceiling system in which the insulation material has been preconditioned according to the material Specifications C549, C665, C739, and C764.
1.5 The specimen preparation techniques outlined in this standard do not cover the characterization of loose-fill materials intended for enclosed applications.
1.6 This practice is be used to characterize mate...
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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: C1373/C1373M − 23
Standard Practice for
Determination of Thermal Resistance of Attic Insulation
1
Systems Under Simulated Winter Conditions
This standard is issued under the fixed designation C1373/C1373M; 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 1.6 This practice is be used to characterize material behav-
ior under controlled steady-state laboratory conditions intended
1.1 This practice presents a laboratory procedure to deter-
to simulate actual temperature conditions of use. The practice
mine the thermal resistance of attic insulation systems under
does not simulate forced air flow conditions.
simulated steady-state winter conditions. The practice applies
only to attic insulation systems that face an open attic air space. 1.7 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
1.2 The thermal resistance of the insulation is inferred from
each system may not be exact equivalents; therefore, each
calculations based on measurements on a ceiling system
system shall be used independently of the other. Combining
consisting of components consistent with the system being
values from the two systems may result in non-conformance
studied. For example, such a system might consist of a gypsum
with the standard.
board or plywood ceiling, wood ceiling joists, and attic
1.7.1 All values shall be reported in both SI and inch-pound
insulation with its top exposed to an open air space. The
units unless specified otherwise by the client.
temperature applied to the gypsum board or plywood shall be
1.8 This standard does not purport to address all of the
in the range of 18 to 24°C [64 to 75°F]. The air temperature
safety concerns, if any, associated with its use. It is the
above the insulation shall correspond to winter conditions and
responsibility of the user of this standard to establish appro-
ranges from –46°C to 10°C [–51 to 50°F]. The gypsum board
priate safety, health, and environmental practices and deter-
or plywood ceiling shall be sealed to prevent direct airflow
mine the applicability of regulatory limitations prior to use.
between the warm and cold sides of the system.
1.9 This international standard was developed in accor-
1.3 This practice applies to a wide variety of loose-fill or
dance with internationally recognized principles on standard-
blanket thermal insulation products including fibrous glass,
ization established in the Decision on Principles for the
rock/slag wool, or cellulosic fiber materials; granular types
Development of International Standards, Guides and Recom-
including vermiculite and perlite; pelletized products; and any
mendations issued by the World Trade Organization Technical
other insulation material that is installed pneumatically or
Barriers to Trade (TBT) Committee.
poured in place. The practice considers the effects on heat
transfer of structures, specifically the ceiling joists, substrate,
2. Referenced Documents
for example, gypsum board, air films, and possible facings,
2
2.1 ASTM Standards:
films, or other materials that are used in conjunction with the
C167 Test Methods for Thickness and Density of Blanket or
insulation.
Batt Thermal Insulations
1.4 This practice measures the thermal resistance of the
C168 Terminology Relating to Thermal Insulation
attic/ceiling system in which the insulation material has been
C177 Test Method for Steady-State Heat Flux Measure-
preconditioned according to the material Specifications C549,
ments and Thermal Transmission Properties by Means of
C665, C739, and C764.
the Guarded-Hot-Plate Apparatus
1.5 The specimen preparation techniques outlined in this C518 Test Method for Steady-State Thermal Transmission
standard do not cover the characterization of loose-fill materi-
Properties by Means of the Heat Flow Meter Apparatus
als intended for enclosed applications. C520 Test Methods for Density of Granular Loose Fill
Insulations
C549 Specification for Perlite Loose Fill Insulation
1
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
2
Measurement. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2023. Published October 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1998. Last previous editio
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: C1373/C1373M − 11 (Reapproved 2017) C1373/C1373M − 23
Standard Practice for
Determination of Thermal Resistance of Attic Insulation
1
Systems Under Simulated Winter Conditions
This standard is issued under the fixed designation C1373/C1373M; 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
1.1 This practice presents a laboratory procedure to determine the thermal resistance of attic insulation systems under simulated
steady-state winter conditions. The practice applies only to attic insulation systems that face an open attic air space.
1.2 The thermal resistance of the insulation is inferred from calculations based on measurements on a ceiling system consisting
of components consistent with the system being studied. For example, such a system might consist of a gypsum board or plywood
ceiling, wood ceiling joists, and attic insulation with its top exposed to an open air space. The temperature applied to the gypsum
board or plywood shall be in the range of 18 to 24°C [64 to 75°F]. The air temperature above the insulation shall correspond to
winter conditions and ranges from –46°C to 10°C [–51 to 50°F]. The gypsum board or plywood ceiling shall be sealed to prevent
direct airflow between the warm and cold sides of the system.
1.3 This practice applies to a wide variety of loose-fill or blanket thermal insulation products including fibrous glass, rock/slag
wool, or cellulosic fiber materials; granular types including vermiculite and perlite; pelletized products; and any other insulation
material that is installed pneumatically or poured in place. The practice considers the effects on heat transfer of structures,
specifically the ceiling joists, substrate, for example, gypsum board, air films, and possible facings, films, or other materials that
are used in conjunction with the insulation.
1.4 This practice measures the thermal resistance of the attic/ceiling system in which the insulation material has been
preconditioned according to the material Specifications C549, C665, C739, and C764.
1.5 The specimen preparation techniques outlined in this standard do not cover the characterization of loose-fill materials intended
for enclosed applications.
1.6 This practice is be used to characterize material behavior under controlled steady-state laboratory conditions intended to
simulate actual temperature conditions of use. The practice does not simulate forced air flow conditions.
1.7 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.7.1 All values shall be reported in both SI and inch-pound units unless specified otherwise by the client.
1
This practice is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal Measurement.
Current edition approved May 1, 2017Sept. 1, 2023. Published May 2017October 2023. Originally approved in 1998. Last previous edition approved in 20112017 as
C1373/C1373M – 11.C1373/C1373M – 11 (2017). DOI: 10.1520/C1373_C1373M-11R17.10.1520/C1373_C1373M-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1373/C1373M − 23
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 and healthsafety, 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.
2. Referenced Documents
2
2.1 ASTM Standards:
C167 Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations
C168 Terminology Relating to Thermal Insulation
C177 Test Meth
...
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