ASTM E2398/E2398M-19

Standard Test Method for Water Capture and Media Retention of Geocomposite Drain Layers for Vegetative (Green) Roof Systems

SIGNIFICANCE AND USE
5.1 Determining these performance characteristics of vegetative (green) roof systems provides information to facilitate the assessment of related engineering aspects of the facility. Such aspects may include structural design requirements, mechanical engineering and thermal design requirements, and fire and life safety requirements.  
5.1.1 Accurate information about the water and media holding capacity of geocomposite drain layers is essential to predict dead load for vegetative (green) roof systems.  
5.2 Determining these performance characteristics of vegetative (green) roof systems provides information to facilitate assessment of the performance of one vegetative (green) roof system relative to one another.  
5.2.1 Water capture is also useful in assessing irrigation requirements for vegetative (green) roof designs.  
5.2.2 Information about the unit media retention volume is required to predict the quantity of material that will be required to construct a vegetative (green) roof with a specified total thickness.
SCOPE
1.1 This test method covers the determination of the water and media retention of synthetic drains layers used in vegetative (green) roof systems.  
1.2 This test method is applicable to geocomposite drain layers that retain water and media in cup-like receptacles on their upper surface. Examples include shaped plastic membranes and closed-cell plastic foam boards.  
1.3 This test method does not apply to products manufactured from water-absorptive materials.  
1.4 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.  
1.5 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 to determine the applicability of regulatory limitations prior to use.  
1.6 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-2019
• ICS: 65.020.20 - Plant growing
• ICS: 91.060.20 - Roofs
• Technical Committee: D08 - Roofing and Waterproofing
• Drafting Committee: D08.24 - Sustainability

Relations

• Replaces: ASTM E2398/E2398M-15a - Standard Test Method for Water Capture and Media Retention of Geocomposite Drain Layers for Vegetative (Green) Roof Systems
• Effective Date: 01-Feb-2019
• Refers: ASTM E2399/E2399M-19 - Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems
• Effective Date: 01-Feb-2019
• Refers: ASTM C920-18 - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 01-Jan-2018
• Refers: ASTM E2114-17 - Standard Terminology for Sustainability Relative to the Performance of Buildings
• Effective Date: 01-Feb-2017
• Refers: ASTM E2399/E2399M-15 - Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems
• Effective Date: 01-Jun-2015
• Refers: ASTM E631-15 - Standard Terminology of Building Constructions
• Effective Date: 01-Mar-2015
• Refers: ASTM E631-14 - Standard Terminology of Building Constructions
• Effective Date: 01-Nov-2014
• Refers: ASTM C920-14a - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 01-Jun-2014
• Refers: ASTM C920-14 - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 01-Jan-2014
• Refers: ASTM C920-11 - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 01-Feb-2011
• Refers: ASTM C920-10 - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 15-Apr-2010
• Refers: ASTM E2114-08 - Standard Terminology for Sustainability Relative to the Performance of Buildings
• Effective Date: 01-Nov-2008
• Refers: ASTM C920-08 - Standard Specification for Elastomeric Joint Sealants
• Effective Date: 15-Jul-2008
• Refers: ASTM E2114-06a - Standard Terminology for Sustainability Relative to the Performance of Buildings
• Effective Date: 01-Dec-2006
• Refers: ASTM E631-06 - Standard Terminology of Building Constructions
• Effective Date: 01-Jun-2006

Overview

ASTM E2398/E2398M-19: Standard Test Method for Water Capture and Media Retention of Geocomposite Drain Layers for Vegetative (Green) Roof Systems is a key international standard developed by ASTM. This standard outlines a consistent method for measuring the water capture and media retention characteristics of synthetic geocomposite drainage layers used in vegetative (green) roof systems. Understanding these properties is essential for building designers, engineers, roofing professionals, and sustainability experts who focus on constructing reliable, efficient, and environmentally responsible green roofs.

Key Topics

• Geocomposite Drain Layers: Focuses on synthetic layers, such as shaped plastic membranes and closed-cell plastic foam boards, used in green roofs to retain and manage water and media.
• Water Capture: Examines the maximum quantity of water a drainage layer can hold, crucial for maintaining plant health, reducing stormwater runoff, and estimating irrigation needs.
• Media Retention: Measures how much growing medium or substrate the drain layer can support, essential for predicting dead load and ensuring structural compatibility.
• Test Methodology: Specifies procedures for sample preparation, water and sand filling, and testing at various inclinations to simulate real-world roof conditions.
• Measurement and Calculation: Details how to calculate unit water capture and media retention volumes, enabling direct comparison between different products.

Applications

Implementing ASTM E2398/E2398M-19 supports vital aspects of vegetative roof design and sustainability initiatives:

• Structural Engineering: Precise values for water and media retention inform dead load calculations, helping engineers design safe and efficient support structures for green roofs.
• Thermal and Waterproofing Design: Knowing the water holding capacity assists mechanical and thermal engineers in optimizing roof assemblies for thermal regulation and waterproofing.
• Fire and Life Safety: Understanding retention properties supports compliance with fire and safety requirements, critical in building codes and regulations.
• Landscape and Irrigation Planning: Using the standard's methodology, designers can estimate irrigation requirements and select materials that enhance plant performance while minimizing resource use.
• Material Specification: Manufacturers and specifiers can benchmark drainage system performance, ensuring compliance and support for LEED or other green building certifications.

Related Standards

For comprehensive results and compliance in vegetative roof design, the following ASTM standards may be relevant:

• ASTM E2397: Practice for Determination of Dead Loads and Live Loads Associated with Vegetative Roof Systems
• ASTM E2399/E2399M: Test Method for Maximum Media Density for Dead Load Analysis of Vegetative Roof Systems
• ASTM E631: Terminology of Building Constructions
• ASTM E2114: Terminology for Sustainability Relative to the Performance of Buildings
• ASTM C920: Specification for Elastomeric Joint Sealants

Practical Value

Adhering to ASTM E2398/E2398M-19 delivers practical benefits such as:

• Risk Reduction: Minimizes structural, drainage, or plant health risks by providing accurate performance data.
• Design Confidence: Enables designers and contractors to make informed decisions on drainage product selection and green roof assembly detailing.
• Regulatory Compliance: Facilitates the assessment of green roof systems against engineering, thermal, fire, and life safety standards.
• Sustainability Goals: Supports evidence-based practices that enhance the resiliency and environmental performance of green buildings.

Using this standard ensures that geocomposite drain layers in green roof systems are evaluated with a globally recognized, reliable method, contributing to safer, more robust, and sustainable vegetative roof installations.

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: E2398/E2398M − 19
Standard Test Method for
Water Capture and Media Retention of Geocomposite Drain
Layers for Vegetative (Green) Roof Systems
ThisstandardisissuedunderthefixeddesignationE2398/E2398M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 E631 Terminology of Building Constructions
E2114 Terminology for Sustainability Relative to the Perfor-
1.1 This test method covers the determination of the water
mance of Buildings
and media retention of synthetic drains layers used in vegeta-
E2399/E2399M Test Method for Maximum Media Density
tive (green) roof systems.
for Dead Load Analysis of Vegetative (Green) Roof
1.2 This test method is applicable to geocomposite drain
Systems
layers that retain water and media in cup-like receptacles on
their upper surface. Examples include shaped plastic mem-
3. Terminology
branes and closed-cell plastic foam boards.
3.1 Definitions:
1.3 This test method does not apply to products manufac-
3.1.1 For terms related to building construction, refer to
tured from water-absorptive materials.
Terminology E631.
1.4 The values stated in either SI units or inch-pound units
3.1.2 For terms related to sustainability relative to the
are to be regarded separately as standard. The values stated in
performance of buildings, refer to Terminology E2114.
each system may not be exact equivalents; therefore, each
3.2 Definitions of Terms Specific to This Standard:
system shall be used independently of the other. Combining
3.2.1 captured water, n—the quantity of water that is re-
values from the two systems may result in non-conformance
tained in the drainage layer of a vegetative (green) roof system
with the standard.
after new water additions have ceased and that cannot escape
the roof except through evaporation or plant transpiration.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2.2 coupon, n—a portion of a material or laboratory
responsibility of the user of this standard to establish appro-
sample from which multiple specimens can be taken for
priate safety, health, and environmental practices and to
testing.
determine the applicability of regulatory limitations prior to
3.2.3 geocomposite drain layer, n—asyntheticsheet,mat,or
use.
panel that is specifically designed to convey water horizontally
1.6 This international standard was developed in accor-
toward the roof deck drains, gutters, or scuppers.
dance with internationally recognized principles on standard-
3.2.3.1 Discussion—Geocomposite drainage layers include
ization established in the Decision on Principles for the
absorptive drainage mats whose principle function is drainage,
Development of International Standards, Guides and Recom-
but which will also contribute to water retention (see retained
mendations issued by the World Trade Organization Technical
water). Some geocomposite drainage layers may incorporate
Barriers to Trade (TBT) Committee.
receptacles on their upper surfaces that will capture water (see
captured water).
2. Referenced Documents
3.2.4 retained water, n—the quantity of water that will be
2.1 ASTM Standards:
retained for a prolonged period against gravity drainage in a
C920 Specification for Elastomeric Joint Sealants
vegetative (green) roof system, or in one of its components,
after new additions by rainfall or artificial irrigation have
This test method is under the jurisdiction ofASTM Committee D08 on Roofing
ceased.
and Waterproofing and is the direct responsibility of Subcommittee D08.24 on
Sustainability.
3.2.4.1 Discussion—Most of this water will not become
Current edition approved Feb. 1, 2019. Published March 2019. Originally
runoff but will be used to the plant-mediated processes of
approved in 2005. Last previous edition approved in 2015 as E2398/E2398M – 15a.
evapo-transpiration.
DOI: 10.1520/E2398_E2398M-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 3 2
3.2.5 unit media retention volume, n—the volume, ft /ft
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3 2
[cm /cm ], that is required to fill a geocomposite drain layer to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the upper most asperities of the geocomposite drain layer.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2398/E2398M − 19
3.2.6 unit water capture volume, n—the maximum volume 8. Procedure
3 2 3 2
of water, ft /ft [cm /cm ], that a geocomposite drain layer can
8.1 Weigh the coupon in a dry condition, and record.
hold at a specified inclination.
8.2 With the coupon on a level surface, fill the receptacles
3.2.6.1 Discussion—For vegetative (green) roofs systems
with water using a dropper. Excise caution not to moisten other
where the geocomposite drain layer will be filled with granular
parts of the coupon.
drainage medium, the actual retained water volume will be less
than the unit water capture volume determined when the
8.3 Transferthecoupontothescaleandrecordtheweightof
geocomposite drain layer is empty.
the coupon with the filled receptacles.
8.4 Using a ruler, measure the distance between the centers
4. Summary of Test Method
of adjacent receptacles along the width and length of the
4.1 This procedure provides a method for measuring the
coupon.
volume of granular media or water, or both, that geocomposite NOTE 1—This measurement methods assumes that the receptacles are
arranged in a rectangular pattern.
drain layers can hold. The test invol
...

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: E2398/E2398M − 15a E2398/E2398M − 19
Standard Test Method for
Water Capture and Media Retention of Geocomposite Drain
Layers for Vegetative (Green) Roof Systems
This standard is issued under the fixed designation E2398/E2398M; 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 test method covers the determination of the water and media retention of synthetic drains layers used in vegetative
(green) roof systems.
1.2 This test method is applicable to geocomposite drain layers that retain water and media in cup-like receptacles on their upper
surface. Examples include shaped plastic membranes and closed-cell plastic foam boards.
1.3 This test method does not apply to products manufactured from water-absorptive materials.
1.4 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.
1.5 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 safety, health, and healthenvironmental practices and to determine the
applicability of regulatory limitations prior to use.
1.6 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:
C920 Specification for Elastomeric Joint Sealants
E631 Terminology of Building Constructions
E2114 Terminology for Sustainability Relative to the Performance of Buildings
E2397E2399/E2399M Practice for Determination of Dead Loads and Live Loads Associated with Test Method for Maximum
Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems
3. Terminology
3.1 Definitions:
3.1.1 For terms related to building construction, refer to Terminology E631.
3.1.2 For terms related to sustainability relative to the performance of buildings, refer to Terminology E2114.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 captured water, n—the quantity of water that is retained in the drainage layer of a vegetative (green) roof system after new
water additions have ceased and that cannot escape the roof except through evaporation or plant transpiration.
3.2.2 coupon, n—a portion of a material or laboratory sample from which multiple specimens can be taken for testing.
3.2.3 geocomposite drain layer, n—a synthetic sheet, mat, or panel that is specifically designed to convey water horizontally
toward the roof deck drains, gutters, or scuppers.
This test method is under the jurisdiction of ASTM Committee D08 on Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.24 on
Sustainability.
Current edition approved Nov. 1, 2015Feb. 1, 2019. Published December 2015March 2019. Originally approved in 2005. Last previous edition approved in 2015 as
E2398/E2398M – 15.E2398/E2398M – 15a. DOI: 10.1520/E2398_E2398M-15A.10.1520/E2398_E2398M-19.
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
E2398/E2398M − 19
3.2.3.1 Discussion—
Geocomposite drainage layers include absorptive drainage mats whose principle function is drainage, but which will also
contribute to water retention (see retained water). Some geocomposite drainage layers may incorporate receptacles on their upper
surfaces that will capture water (see captured water).
3.2.4 retained water, n—the quantity of water that will be retained for a prolonged period against gravity drainage in a vegetative
(green) roof system, or in one of its components, after new additions by rainfall or artificial irrigation have ceased.
3.2.4.1 Discussion—
Most of this water will not become runoff but will be used to the plant-mediated processes of evapo-transpiration.
3 2 3 2
3.2.5 unit media retention volume, n—the volume, ft /ft [cm /cm ], that is required to fill a geocomposite drain layer to the
upper most asperities of the geocomposite drain layer.
3 2 3 2
3.2.6 unit water capture volume, n—the maximum volume of water, ft /ft [cm /cm ], that a geocomposite drain layer can hold
at a specified inclination.
3.2.6.1 Discussion—
For vegetative (green) roofs systems where the geocomposite drain layer will be filled with granular drainage medium, the actual
volume is assumed to be 25 % of the measured volume. This assumption will allow a direct comparison between geocomposite
sheet drains without, regard to retained water volume will be less than the granular drainage media used. In computing the actual
water capture ofunit water capture volume a geocomposite sheet drain employed in a specific vegetative (green) roof assembly,
the porosity of the granular drainage medium used must be considered (Practice determined when the geocomposite drain layer
is empty.E2397).
4. Summary of Test Method
4.1 This procedure provides a method for measuring the volume of granular media or water, or both, that geocomposite drain
layers can hold. The test involves filling the geocomposite drain layers with sand and water to establish the respective volumes.
Since water capture will be influenced by the inclination of the geocomposite drain layer, the tests are conducted at several
inclinations.
5. Significance and Use
5.1 Determining these per
...