ASTM E2398-05

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Designation:E2398–05
Standard Test Method for
Water Capture and Media Retention of Geocomposite Drain
1
Layers for Green Roof Systems
This standard is issued under the fixed designation E2398; 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 3.1.1 For terms related to building construction, refer to
Terminology E631.
1.1 This test method covers the determination of the water
3.1.2 For terms related to sustainability relative to the
and media retention of synthetic drains layers used in green
performance of buildings, refer to Terminology E2114.
roof systems.
3.2 Definitions of Terms Specific to This Standard:
1.2 This standard is applicable to geocomposite drain layers
3.2.1 captured water, n—the quantity of water that is
that retain water and media in cup-like receptacles on their
retained in the drainage layer of a green roof system after new
upper surface. Examples include shaped plastic membranes
water additions have ceased and that cannot escape the roof
and closed-cell plastic foam boards
except through evaporation or plant transpiration.
1.3 This standard does not apply to products manufactured
3.2.2 coupon, n—a portion of a material or laboratory
from water-absorptive materials.
sample from which multiple specimens can be taken for
1.4 The values stated in inch-pound units are to be regarded
testing.
as standard. The values given in parentheses are mathematical
3.2.3 geocomposite drain layer, n—a synthetic sheet, mat,
conversions to SI units that are provided for information only
or panel that is specifically designed to convey water horizon-
and are not considered standard.
tally toward the roof deck drains, gutters, or scuppers.
1.5 This standard does not purport to address all of the
3.2.3.1 Discussion—Geocomposite drainage layers include
safety concerns, if any, associated with its use. It is the
absorptive drainage mats whose principle function is drainage,
responsibility of the user of this standard to establish appro-
but which will also contribute to water retention (see retained
priate safety and health practices and to determine the
water). Some geocomposite drainage layers may incorporate
applicability of regulatory limitations prior to use.
receptacles on their upper surfaces that will capture water (see
2. Referenced Documents captured water).
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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
E631 Terminology of Building Constructions
green roof system, or in one of its components, after new
E2114 Terminology for Sustainability Relative to the Per-
additions by rainfall or artificial irrigation have ceased.
formance of Buildings
3.2.4.1 Discussion—Most of this water will not become
E2397 Practice for Determination of Dead Loads and Live
runoff but will be used to the plant-mediated processes of
Loads associated with Green Roof Systems
evapo-transpiration.
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3. Terminology
3.2.5 unit media retention volume, n—the volume, ft /
2 3 2
ft , (cm /cm ) that is required to fill a geocomposite drain layer
3.1 Definitions:
to the upper most asperities of the geocomposite drain layer.
3.2.6 unit water capture volume, n—the maximum volume
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3 2 3 2
This test method is under the jurisdiction of ASTM Committee E60 on
of water (ft /ft ) (cm /cm ) that a geocomposite drain layer can
Sustainability and is the direct responsibility of Subcommittee E60.01 on Buildings
hold at a specified inclination.
and Construction.
3.2.6.1 Discussion—For green roofs systems where the
Current edition approvedAug. 15, 2005. PublishedAugust 2005. DOI: 10.1520/
E2398-05.
geocomposite drain layer will be filled with granular drainage
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
medium, the actual volume is assumed to be 25 % of the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
measured volume. This assumption will allow a direct com-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. parison between geocomposite sheet drains without, regard to
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E2398–05
the granular drainage media used. In computing the actual 8.4 Using a ruler, measure the distance between the centers
water capture of a geocomposite sheet drain employed in a of adjacent receptacles along the width and length of the
specific green roof assembly, the porosity of the granular coupon.
d
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