ASTM D8257/D8257M-22

Standard Specification for Mechanically Attached Polymeric Roof Underlayment Used in Steep Slope Roofing

SCOPE
1.1 This specification addresses mechanically attached polymeric roof underlayment used in steep slope roofing.  
1.2 The objective of this specification is to provide a finished product that will be used as a water-shedding underlayment layer on steep sloped roofs prior to and after installation of the primary roof covering.  
1.3 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 nonconformance with the 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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-Jan-2022
• ICS: 91.060.20 - Roofs
• ICS: 91.100.50 - Binders. Sealing materials
• Technical Committee: D08 - Roofing and Waterproofing
• Drafting Committee: D08.02 - Steep Roofing Products and Assemblies

Relations

• Refers: ASTM E96/E96M-24 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 01-Mar-2024
• Refers: ASTM E96/E96M-23 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 15-Nov-2023
• Refers: ASTM D1079-20 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-May-2020
• Refers: ASTM D1204-14(2020) - Standard Test Method for Linear Dimensional Changes of Nonrigid Thermoplastic Sheeting or Film at Elevated Temperature
• Effective Date: 01-Apr-2020
• Refers: ASTM D5035-11(2019) - Standard Test Method for Breaking Force and Elongation of Textile Fabrics (Strip Method)
• Effective Date: 01-Jul-2019
• Refers: ASTM D228/D228M-19 - Standard Test Methods for Sampling, Testing, and Analysis of Asphalt Roll Roofing, Cap Sheets, and Shingles Used in Roofing and Waterproofing
• Effective Date: 01-May-2019
• Refers: ASTM D1079-18 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Dec-2018
• Refers: ASTM D1079-18e1 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Dec-2018
• Refers: ASTM D228/D228M-18 - Standard Test Methods for Sampling, Testing, and Analysis of Asphalt Roll Roofing, Cap Sheets, and Shingles Used in Roofing and Waterproofing
• Effective Date: 01-Nov-2018
• Refers: ASTM F1667-18 - Standard Specification for Driven Fasteners: Nails, Spikes, and Staples
• Effective Date: 01-Sep-2018
• Refers: ASTM F1667-17 - Standard Specification for Driven Fasteners: Nails, Spikes, and Staples
• Effective Date: 01-Mar-2017
• Refers: ASTM D228/D228M-16 - Standard Test Methods for Sampling, Testing, and Analysis of Asphalt Roll Roofing, Cap Sheets, and Shingles Used in Roofing and Waterproofing
• Effective Date: 01-Nov-2016
• Refers: ASTM D1079-16 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Feb-2016
• Refers: ASTM D4869/D4869M-16 - Standard Specification for Asphalt-Saturated Organic Felt Underlayment Used in Steep Slope Roofing
• Effective Date: 01-Jan-2016
• Refers: ASTM F1667-15 - Standard Specification for Driven Fasteners: Nails, Spikes, and Staples
• Effective Date: 01-Sep-2015

Overview

ASTM D8257/D8257M-22 is a standard specification developed by ASTM International that outlines the requirements for mechanically attached polymeric roof underlayment used in steep slope roofing applications. This specification ensures that the underlayment serves as a reliable water-shedding layer both before and after the installation of the primary roof covering. The standard addresses essential quality, performance, and safety parameters to support consistency and durability in steep slope roofing systems.

Key Topics

• Mechanically Attached Polymeric Roof Underlayment: The specification focuses on synthetic polymer-based sheet materials, such as those made from polyethylene or polypropylene, which function as secondary water-shedding layers beneath primary roof coverings.
• Steep Slope Roofing: The standard is specifically intended for roofing installations where the slope is significant enough to require specialized underlayment materials that ensure water resistance and stability.
• Physical and Performance Requirements:
  • Uniform thickness and defect-free appearance
  • Slip resistance to enhance safety for installers
  • Conformance to various test methods assessing unrolling ability, pliability, tensile and tearing strength, fastener pull-through resistance, hydrostatic resistance, water vapor and liquid transmission, and dimensional stability
• Climate and Durability Testing: Materials are subjected to thermal cycling and laboratory accelerated weathering to simulate real-world exposure to heat, light, and moisture, ensuring long-term performance.
• Dual Measurement Systems: The standard accepts both SI and inch-pound units, promoting international usage and compliance.
• Packaging and Marking: Each roll of underlayment must be clearly labeled with the manufacturer's details and the ASTM designation for traceability and quality assurance.

Applications

Polymeric roof underlayments specified by ASTM D8257/D8257M-22 are widely used in:

• Residential and Commercial Steep Slope Roofs: Providing a secondary barrier against water infiltration beneath shingles, tiles, or metal roofing.
• New Construction and Roof Replacement Projects: Ensuring prolonged protection of roofing decks from moisture while awaiting the installation of the final roofing material.
• Extreme Weather Environments: The durability requirements make these underlayments suitable for regions with substantial temperature fluctuations or intense weather conditions.

The standard is crucial for:

• Architects and designers specifying roofing systems
• Roof underlayment manufacturers and quality control labs
• Roofing contractors installing steep slope systems
• Code officials and inspectors verifying compliance with roofing codes and best practices

Related Standards

ASTM D8257/D8257M-22 references several critical ASTM standards, including:

• ASTM D146/D146M: Sampling and testing bitumen-saturated felts and woven fabrics
• ASTM D4869/D4869M: Specification for asphalt-saturated organic felt underlayment used in steep slope roofing
• ASTM D5035: Breaking force and elongation of textile fabrics
• ASTM D751: Test methods for coated fabrics
• ASTM F1667: Specification for driven fasteners such as roofing nails and staples
• ASTM G151/G155: Practices for exposing nonmetallic materials in laboratory light sources

These related standards cover test methods and materials commonly used in roofing and waterproofing applications and support harmonized best practices for the roofing industry.

Practical Value

Implementing ASTM D8257/D8257M-22 helps manufacturers, specifiers, and installers ensure that polymeric roof underlayments used in steep slope roofing:

• Meet stringent water-resistance and durability benchmarks
• Are tested under realistic and challenging environmental conditions
• Enhance worker safety and application reliability through slip-resistant features
• Support regulatory compliance in multiple jurisdictions

By adopting this standard, construction professionals can ensure their roofing systems deliver long-lasting performance and consistent quality, regardless of climate or installation scenario.

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:D8257/D8257M −22
Standard Specification for
Mechanically Attached Polymeric Roof Underlayment Used
in Steep Slope Roofing
This standard is issued under the fixed designation D8257/D8257M; 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 Shingles Used in Roofing and Waterproofing
D751 Test Methods for Coated Fabrics
1.1 This specification addresses mechanically attached
D1079 Terminology Relating to Roofing and Waterproofing
polymeric roof underlayment used in steep slope roofing.
D1204 Test Method for Linear Dimensional Changes of
1.2 The objective of this specification is to provide a
Nonrigid Thermoplastic Sheeting or Film at Elevated
finished product that will be used as a water-shedding under-
Temperature
layment layer on steep sloped roofs prior to and after installa-
D4533/D4533M Test Method for Trapezoid Tearing
tion of the primary roof covering.
Strength of Geotextiles
1.3 The values stated in either SI units or inch-pound units D4798/D4798M Practice for Accelerated Weathering Test
Conditions and Procedures for Bituminous Materials
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each (Xenon-Arc Method)
D4869/D4869M Specification for Asphalt-Saturated Or-
system shall be used independently of the other. Combining
values from the two systems may result in nonconformance ganic Felt Underlayment Used in Steep Slope Roofing
D5035 Test Method for Breaking Force and Elongation of
with the standard.
Textile Fabrics (Strip Method)
1.4 This standard does not purport to address all of the
E96/E96M Test Methods for Gravimetric Determination of
safety concerns, if any, associated with its use. It is the
Water Vapor Transmission Rate of Materials
responsibility of the user of this standard to establish appro-
F1667 Specification for Driven Fasteners: Nails, Spikes, and
priate safety, health, and environmental practices and deter-
Staples
mine the applicability of regulatory limitations prior to use.
G113 Terminology Relating to Natural andArtificial Weath-
1.5 This international standard was developed in accor-
ering Tests of Nonmetallic Materials
dance with internationally recognized principles on standard-
G151 Practice for Exposing Nonmetallic Materials inAccel-
ization established in the Decision on Principles for the
erated Test Devices that Use Laboratory Light Sources
Development of International Standards, Guides and Recom-
G155 Practice for Operating XenonArc LampApparatus for
mendations issued by the World Trade Organization Technical
Exposure of Materials
Barriers to Trade (TBT) Committee.
3. Terminology
2. Referenced Documents
3.1 Definitions—For definitions of terms used in this
2.1 ASTM Standards:
specification, refer to Terminologies D1079 and G113.
D146/D146M Test Methods for Sampling and Testing
Bitumen-Saturated Felts and Woven Fabrics for Roofing
3.2 Definitions of Terms Specific to This Standard:
and Waterproofing
3.2.1 polymeric roof underlayment—a sheet material pri-
D228/D228M Test Methods for Sampling, Testing, and
marily composed of one or more synthetic polymers for use as
Analysis of Asphalt Roll Roofing, Cap Sheets, and a secondary water-shedding layer on steep sloped roofs when
installed below the primary roof covering.
3.2.1.1 Discussion—Examples include polyethylene,
This specification is under the jurisdiction of ASTM Committee D08 on
polypropylene, or polyethylene terephthalate.
Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.02
on Steep Roofing Products and Assemblies.
Current edition approved Feb. 1, 2022. Published February 2022. Originally 4. Workmanship, Finish, and Appearance
approved in 2020. Last previous edition approved in 2020 as D8257/D8257M – 20.
4.1 The polymeric roof underlayment shall be supplied in
DOI: 10.1520/D8257_D8257M-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or roll form.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.2 The polymeric roof underlayment shall be uniform in
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. thickness and appearance. It shall be free of visible defects
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8257/D8257M−22
suchasholes,raggedoruntrueedges,breaks,cracks,tears,and 7. Test Methods
protruding edges of reinforcement.
7.1 Conditioning—Unless otherwise stated, all specimens to
4.3 The surface of the underlayment sheet shall be designed
be tested shall be conditioned for a minimum period of 24 h at
to provide traction and slip resistance to the applicator.
23 6 2 °C [73 6 4 °F] and 50 6 10 % relative humidity (RH)
prior to testing.
NOTE 1—The intent of 4.3 is to recognize that surface slipperiness is
important when working on a roof and, while no test method is specified
NOTE 2—The positive and negative variations specified, along with the
in this standard, several methods for assessing the relative slipperiness of
temperature and relative humidity settings, are the maximum allowed
surfaces are available. It is the further intent of this paragraph to ensure
operational fluctuations from the set points specified under equilibrium
that, whatever method is used, the friction coefficient or resistance to
conditions. They do not imply that the set points can be higher or lower
slipping of the surface of these products should be at least as great as
than those specified.
asphalt-saturated felt shingle underlayment tested under the same condi-
tions of temperature and wetness as agreed between purchaser and seller.
7.2 Unrolling—The polymeric roof underlayment shall not
crack nor be so sticky as to cause tearing, delamination, or
5. Physical Requirements
other damage upon being unrolled at temperatures between 0
5.1 The polymeric roof underlayment shall conform to the
and 60 °C [32 and 140 °F].Afinished roll shall be conditioned
physical requirements prescribed in Table 1.
at each of the aforementioned temperatures for 24 h, and then
unrolled within 5 min (6 1 min) at laboratory conditions.
6. Sampling
7.3 Pliability—Ten 25.4 mm by 203 mm [1 in. by 8 in.]
6.1 The samples to be tested for conformance to this
specimens,fivetakeninthemachinedirectionandfivetakenin
specification shall be taken directly from rolls randomly
the cross-machine direction, are maintained at –10 6 2 °C [14
selected in accordance with Test Methods D146/D146M.
6 4 °F] for a minimum of 24 h and the exposed surface is bent
6.2 The specimens shall be cut from the selected roll so that over a 3.2 mm [ ⁄8 in.] diameter steel mandrel through a 90°
no specimen is taken from a portion of the roll that exhibits angle. Complete the entire procedure inside the refrigerated
damage from handling or prolonged exposure to light. unit, including bending over the mandrel, within 2 61s.
TABLE 1 Requirements for Polymeric Roof Underlayments
Test Requirement Specimen Type Test Method Conditions of Acceptance
Unrolling As received 7.2 No visible cracking, tearing, or delamination
of underlayment
Pliability As received 7.3 No visible cracking or delamination of
underlayment
Water Vapor Transmission As received 7.4 Results shall be reported in Perms
Liquid Water Transmission As received 7.5 Shall meet the “PASS” requirements of
ASTM D4869/D4869M
Linear Dimensional Change As received 7.6 Max. linear change of –2.5 to +1 %
Tensile Strength As received 7.7 Min. 3.5 kN/m [20 lbf/in.]
(machine and cross-machine direction) After Thermal Cycling 7.7 and 7.11
After Laboratory Accelerated Weathering 7.7 and 7.12
Tearing Strength As received 7.8 Min. 67 N [15 lbf]
(machine and cross-machine direction) After Thermal Cycling 7.8 and 7.11
After Laboratory Accelerated Weathering 7.8 and 7.12
Fastener Pull-Through Resistance As received 7.9 Min. 111 N [25 lbf]
After Thermal Cycling 7.9 and 7.11
After Laboratory Accelerated Weathering 7.9 and 7.12
Hydrostatic Resistance As received 7.10 No water shall pass through any specimen
After Thermal Cycling 7.10 and 7.11
After Laboratory Accelerated Weathering 7.10 and 7.12
Thermal Cycling As received 7.11 No visible damage such as peeling,
chipping, crazing, splitting, cracking, flaking,
or pitting
A
Laboratory A
...

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: D8257/D8257M − 20 D8257/D8257M − 22
Standard Specification for
Mechanically Attached Polymeric Roof Underlayment Used
in Steep Slope Roofing
This standard is issued under the fixed designation D8257/D8257M; 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 specification addresses mechanically attached polymeric roof underlayment used in steep slope roofing.
1.2 The objective of this specification is to provide a finished product that will be used as a water-shedding underlayment layer
on steep sloped roofs prior to and after installation of the primary roof covering.
1.3 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 nonconformance with the 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 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
2.1 ASTM Standards:
D146/D146M Test Methods for Sampling and Testing Bitumen-Saturated Felts and Woven Fabrics for Roofing and
Waterproofing
D228/D228M Test Methods for Sampling, Testing, and Analysis of Asphalt Roll Roofing, Cap Sheets, and Shingles Used in
Roofing and Waterproofing
D751 Test Methods for Coated Fabrics
D1079 Terminology Relating to Roofing and Waterproofing
D1204 Test Method for Linear Dimensional Changes of Nonrigid Thermoplastic Sheeting or Film at Elevated Temperature
D4533/D4533M Test Method for Trapezoid Tearing Strength of Geotextiles
D4798/D4798M Practice for Accelerated Weathering Test Conditions and Procedures for Bituminous Materials (Xenon-Arc
Method)
D4869/D4869M Specification for Asphalt-Saturated Organic Felt Underlayment Used in Steep Slope Roofing
This specification is under the jurisdiction of ASTM Committee D08 on Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.02 on Steep
Roofing Products and Assemblies.
Current edition approved Dec. 15, 2020Feb. 1, 2022. Published December 2020February 2022. Originally approved in 2020. Last previous edition approved in 2020 as
D8257/D8257M – 20. DOI: 10.1520/D8257_D8257M-20.10.1520/D8257_D8257M-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For 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
D8257/D8257M − 22
D5035 Test Method for Breaking Force and Elongation of Textile Fabrics (Strip Method)
E96/E96M Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
F1667 Specification for Driven Fasteners: Nails, Spikes, and Staples
G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G155 Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials
3. Terminology
3.1 Definitions—For definitions of terms used in this specification, refer to Terminologies D1079 and G113.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 polymeric roof underlayment—a sheet material primarily composed of one or more synthetic polymers for use as a secondary
water-shedding layer on steep sloped roofs when installed below the primary roof covering.
3.2.1.1 Discussion—
Examples include polyethylene, polypropylene, or polyethylene terephthalate.
4. Workmanship, Finish, and Appearance
4.1 The polymeric roof underlayment shall be supplied in roll form.
4.2 The polymeric roof underlayment shall be uniform in thickness and appearance. It shall be free of visible defects such as holes,
ragged or untrue edges, breaks, cracks, tears, and protruding edges of reinforcement.
4.3 The surface of the underlayment sheet shall be designed to provide traction and slip resistance to the applicator.
NOTE 1—The intent of 4.3 is to recognize that surface slipperiness is important when working on a roof and, while no test method is specified in this
standard, several methods for assessing the relative slipperiness of surfaces are available. It is the further intent of this paragraph to ensure that, whatever
method is used, the friction coefficient or resistance to slipping of the surface of these products should be at least as great as asphalt-saturated felt shingle
underlayment tested under the same conditions of temperature and wetness as agreed between purchaser and seller.
5. Physical Requirements
5.1 The polymeric roof underlayment shall conform to the physical requirements prescribed in Table 1.
6. Sampling
6.1 The samples to be tested for conformance to this specification shall be taken directly from rolls randomly selected in
accordance with Test Methods D146/D146M.
6.2 The specimens shall be cut from the selected roll so that no specimen is taken from a portion of the roll that exhibits damage
from handling or prolonged exposure to light.
7. Test Methods
7.1 Conditioning—Unless otherwise stated, all specimens to be tested shall be conditioned for a minimum period of 24 h at 23
6 2 °C [73 6 4 °F] and 50 6 10 % relative humidity (RH) prior to testing.
NOTE 2—The positive and negative variations specified, along with the temperature and relative humidity settings, are the maximum allowed operational
fluctuations from the set points specified under equilibrium conditions. They do not imply that the set points can be higher or lower than those specified.
7.2 Unrolling—The polymeric roof underlayment shall not crack nor be so sticky as to cause tearing, delamination, or other
damage upon being unrolled at temperatures between 0 and 60 °C [32 and 140 °F]. A finished roll shall be conditioned at each of
the aforementioned temperatures for 24 h, and then unrolled within 5 min (6 1 min) at laboratory conditions.
7.3 Pliability—Ten 25.4 mm by 203 mm [1 in. by 8 in.] specimens, five taken in the machine direction and five taken in the
D8257/D8257M − 22
TABLE 1 Requirements for Polymeric Roof Underlayments
Test Requirement Specimen Type Test Method Conditions of Acceptance
Unrolling As received 7.2 No visible cracking, tearing, or delamination
of underlayment
Pliability As received 7.3 No visible cracking or delamination of
underlayment
Water Vapor Transmission As received 7.4 Results shall be reported in Perms
Liquid Water Transmission As received 7.5 Shall meet the “PASS” requirements of
ASTM D4869/D4869M
Linear Dimensional Change As received 7.6 Max. linear change of –2.5 to +1 %
Tensile Strength As received 7.7 Min. 3.5 kN/m [20 lbf/in.]
(machine and cross-machine direction) After Thermal Cycling 7.7 and 7.11
After Laboratory Accelerated Weathering 7.7 and 7.12
Tearing Strength As received 7.8 Min. 67 N [15 lbf]
(machine and cross-machine direction) After Thermal Cycling 7.8 and 7.11
After Laboratory Accelerated Weathering 7.8 and 7.12
Fastener Pull-Through Resistance As received 7.9 Min. 111 N [25 lbf]
After Thermal Cycling 7.9 and 7.11
After Laboratory Accelerated Weathering 7.9 and 7.12
Hydrostatic Resistance As received 7.10 No water shall pass through any specimen
After Thermal Cycling 7.10 and 7.11
After Laboratory Accelerated Weathering 7.10 and 7.12
Thermal Cycling As received 7.11 No visible damage such as peeling,
chipping, crazing, splitting, cracking, flaking,
or pitting
A
Laboratory Accelerated Weathering As received 7.12 No visible damage such as peeling,
chipping, crazing, splitting, cracking, flaking,
or pitting
A
The effect of laboratory accelerated weathering on the tensile strength, tearing strength, fa
...