ASTM E2397-05

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Designation:E2397–05
Standard Practice for
Determination of Dead Loads and Live Loads associated
with Green Roof Systems
This standard is issued under the fixed designation E2397; 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 priate safety and health practices and to determine the
applicability of regulatory limitations prior to use.
1.1 This practice covers a standardized procedure for pre-
dicting the system weight of a green roof system.
2. Referenced Documents
1.2 The procedure addresses the loads associated with green
2.1 ASTM Standards:
roof systems. Components that are typically encountered in
C29/C29M Test Method for Bulk Density (“Unit Weight”)
green roof systems include: membranes, non-absorptive plastic
and Voids in Aggregate
sheet components, metallic layers, fabrics, geocomposite drain
E631 Terminology of Building Constructions
layers, synthetic reinforcing layers, cover/recover boards, in-
E2114 Terminology for Sustainability Relative to the Per-
sulation materials, growth media, granular drainage media, and
formance of Buildings
plant materials.
E2396 Test Method for Saturated Water Permeability of
1.3 This procedure also addresses the weight of the green
Granular Drainage Media [Falling-Head Method] for
roof system under two conditions: (1) weight under drained
Green Roof Systems
conditions after new water additions by rainfall or irrigation
E2398 Test Method forWater Capture and Media Retention
have ceased (this includes the weight of retained water and
of Geocomposite Drain Layers for Green Roof Systems
captured water), and (2) weight when rainfall or irrigation is
E2399 Test Method for Maximum Media Density for Dead
actively occurring and the drainage layer is completely filled
Load Analysis of Green Roof Systems
with water. The first condition is considered the dead load of
the green roof system. The difference in weight between the
3. Terminology
first and second conditions, approximated by the weight of
3.1 Definitions:
transient water in the drainage layer, is considered a live
3.1.1 For terms related to building construction, refer to
load.
Terminology E631.
1.4 This procedure does not address point or line loads
3.1.2 For terms related to sustainability relative to the
associated with architectural elements that are not essential
performance of buildings, refer to Terminology E2114.
components of a particular green roof system. These architec-
3.2 Definitions of Terms Specific to This Standard:
tural elements may include pavement, walls, and masonry, and
3.2.1 captured water, n—the quantity of water that is
so forth.
retained in the drainage layer of a green roof system after new
1.5 This procedure does not address live loads associated
water additions have ceased and that cannot escape the roof
with construction activities.
except through evaporation or plant transpiration.
1.6 This procedure does not address live loads associated
3.2.1.1 Discussion—Water capture is a design technique for
with snow or wind.
enhancing the water holding properties of a green roof system.
1.7 The values stated in inch-pound units are to be regarded
Water may be captured using a number of techniques, includ-
as standard. The values given in parentheses are mathematical
ing receptacles built into a geocomposite drain layer, trays, and
conversions to SI units that are provided for information only
restricting drainage in order to hold water within the drainage
and are not considered standard.
layer.
1.8 This standard does not purport to address all of the
In some green roof systems a granular course at the bottom
safety concerns, if any, associated with its use. It is the
of the system provides both drainage and water capture
responsibility of the user of this standard to establish appro-
functions. In this case the captured water applies only to the
This Practice is under the jurisdiction of ASTM Committee E60 on Sustain-
ability and is the direct responsibility of Subcommittee E60.01 on Buildings and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Construction. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approvedAug. 15, 2005. PublishedAugust 2005. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
E2397-05. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2397–05
thickness of the granular course for which drainage is re- 3.2.8.1 Discussion—Transient water fills the open space,
stricted. including pore spaces. This water can only be held for a period
Amethodfordeterminingthecapturedwaterassociatedwith of minutes and drains immediately when rainfall additions end.
geocomposites based on the unit water capture volume is This moisture contributes to the live load of the system.
provided in Test Method E2398. The quantity of captured
4. Summary of Practice
water will depend on whether or not the upper surface of the
geocomposite drain layer is in-filled with granular media. 4.1 This practice describes a systematic procedure for esti-
matingthedeadloadandtransientwaterliveloadofgreenroof
3.2.2 geocomposite drain layer, n—a synthetic sheet, mat,
systems using information about the green roof components
or panel that is specifically designed to convey water horizon-
that are available from laboratory analysis.
tally toward the roof deck drains, gutters, or scuppers.
3.2.2.1 Discussion—Geocomposite drainage layers include
5. Significance and Use
absorptive drainage mats whose principle function is drainage,
5.1 This practice addresses performance characteristics for
but which will also contribute to water retention (see retained
green roof systems with respect to the dead load and transient
water). Some geocomposite drainage layers may incorporate
water live load of the entire system.
receptacles on their upper surfaces that will capture water (see
5.2 Determining these performance characteristics of green
captured water)
roof systems provides information to facilitate the assessment
3.2.3 maximum media density, n—the density of a mixed
of related engineering aspects of the facility. Such aspects may
media material determined after it has been subjected to a
includestructuraldesignrequirements,mechanicalengineering
specific amount of compaction and hydrated by immersion to
and thermal design requirements, and fire and life safety
simulate prolonged exposure to both foot traffic and rainfall.
requirements.
3.2.3.1 Discussion—The maximum media density applies
5.3 Determining these performance characteristics of green
to media in a drained condition. The measurement of the
roof systems provides information to facilitate assessment of
maximum media density is provided in Test Method E2396.
the performance of one green roof system relative to another.
3.2.4 maximum media water retention—the quantity of
6. Apparatus
water held in a media layer at the maximum media density.
6.1 Apparatus:
3.2.4.1 Discussion—A procedure for measuring the maxi-
mum media water retention is provided in Test Method E2399. 6.1.1 Scale, accurate to 0.005 oz (0.14 g),
6.1.2 Metal mesh with sieve opening size of U.S. #30 (0.6
3.2.5 retained water, n—water which is held for a period of
mm), or larger, suspended from a drain stand,
hours or days but would eventually drain out given enough
6.1.3 Pan, and
time in the absence of evaporation or plant transpiration.
6.1.4 Water bath.
3.2.5.1 Discussion—Retained water is the quantity of water
2 2
6.2 Units of measure: lb/ft (kg/m ).
that is held for a prolonged period against gravity drainage in
a green roof system, or in one of its components, after new
7. Procedure
additions by rainfall or artificial irrigation have ceased. Ne-
7.1 Weight of all non-absorptive plastic sheet components,
glecting the effects of capillary rise, evaporation, and plant
excluding fabrics: Using the scale, weigh a 4-in. by 4-in.
transpiration all of this water would eventually produce runoff.
(10-cm by 10-cm) piece. Multiply this weight by 9 (100) to
However, in practice most of this water will not become runoff
2 2
convert to unit weight in lb/ft (kg/m ) and record.
butwillbelosttoevaporationandtheplant-mediatedprocesses
7.2 Weight of all fabrics: Weigh a 4-in. by 4-in. (10-cm by
of transpiration. This procedure describes standardized meth-
10-cm) sample in the dry condition. Multiply this weight by 9
ods for estimating the quantity of water retained in a green roof
2 2
(100) to convert to unit weight in lb/ft (kg/m ), and record.
system.
This is the dry unit weight. Immerse the sample i
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