ASTM_E_2398_-_E_2398M_-_15a.pdf

Designation:E2398/E2398M15aStandard Test Method forWater Capture and Media Retention of Geocomposite DrainLayers for Vegetative(Green)Roof Systems1This standard is issued under the fixed designation E2398/E2398M;the number immediately following the designation indicates the yearof 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.Scope1.1 This test method covers the determination of the waterand media retention of synthetic drains layers used in vegeta-tive(green)roof systems.1.2 This test method is applicable to geocomposite drainlayers that retain water and media in cup-like receptacles ontheir upper surface.Examples include shaped plastic mem-branes and closed-cell plastic foam boards.1.3 This test method does not apply to products manufac-tured from water-absorptive materials.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C920 Specification for Elastomeric Joint SealantsE631 Terminology of Building ConstructionsE2114 Terminology for Sustainability Relative to the Perfor-mance of BuildingsE2397 Practice for Determination of Dead Loads and LiveLoads Associated with Vegetative(Green)Roof Systems3.Terminology3.1 Definitions:3.1.1 For terms related to building construction,refer toTerminology E631.3.1.2 For terms related to sustainability relative to theperformance of buildings,refer to Terminology E2114.3.2 Definitions of Terms Specific to This Standard:3.2.1 captured water,nthe quantity of water that is re-tained in the drainage layer of a vegetative(green)roof systemafter new water additions have ceased and that cannot escapethe roof except through evaporation or plant transpiration.3.2.2 coupon,na portion of a material or laboratorysample from which multiple specimens can be taken fortesting.3.2.3 geocomposite drain layer,na synthetic sheet,mat,orpanel that is specifically designed to convey water horizontallytoward the roof deck drains,gutters,or scuppers.3.2.3.1 DiscussionGeocomposite drainage layers includeabsorptive drainage mats whose principle function is drainage,but which will also contribute to water retention(see retainedwater).Some geocomposite drainage layers may incorporatereceptacles on their upper surfaces that will capture water(seecaptured water).3.2.4 retained water,nthe quantity of water that will beretained for a prolonged period against gravity drainage in avegetative(green)roof system,or in one of its components,after new additions by rainfall or artificial irrigation haveceased.3.2.4.1 DiscussionMost of this water will not becomerunoff but will be used to the plant-mediated processes ofevapo-transpiration.3.2.5 unit media retention volume,nthe volume,ft3/ft2cm3/cm2,that is required to fill a geocomposite drain layer tothe upper most asperities of the geocomposite drain layer.3.2.6 unit water capture volume,nthe maximum volumeof water,ft3/ft2cm3/cm2,that a geocomposite drain layer canhold at a specified inclination.3.2.6.1 DiscussionFor vegetative(green)roofs systemswhere the geocomposite drain layer will be filled with granulardrainage medium,the actual volume is assumed to be 25%ofthe measured volume.This assumption will allow a direct1This test method is under the jurisdiction ofASTM Committee D08 on Roofingand Waterproofing and is the direct responsibility of Subcommittee D08.24 onSustainability.Current edition approved Nov.1,2015.Published December 2015.Originallyapproved in 2005.Last previous edition approved in 2015 as E2398/E2398M 15.DOI:10.1520/E2398_E2398M-15A.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 comparison between geocomposite sheet drains without,re-gard to the granular drainage media used.In computing theactual water capture of a geocomposite sheet drain employed ina specific vegetative(green)roof assembly,the porosity of thegranular drainage medium used must be considered(PracticeE2397).4.Summary of Test Method4.1 This procedure provides a method for measuring thevolume of granular media or water,or both,that geocomposi