ASTM_D_7851_-_17.pdf

Designation:D785117Standard Guide forDesign of Sustainable,Low-Slope Roofing Systems1This standard is issued under the fixed designation D7851;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide provides guidance and considerations relatedto designing sustainable low-sloped roofing systems,includingexposed membrane roofs,membranes covered with vegetative(green)overburden systems,ballasted roofs,and protectedmembrane roofing assemblies.A sustainable roofing systemminimizes environmental impact,conserves energy,and hasmaximized service life.1.2 The primary purpose of a roofing system is to weather-proof the buildings top surface.Implementing a sustainableroofing system is the intent of this guide.1.3 This guide acknowledges that many factors outside thedesigners control affect the longevity of a roofing system.Thedesigner may rely on industry literature(X1.1)and personalexperience with roofing systems to estimate the design life.1.4 The premise of this guide is to focus attention onenvironmental and other factors that may affect the roofingsystem over its service life.By considering these factors andincorporating into the roofing system design certain featuresthat mitigate these factors and their potential adverse effects onthe roofing system,the roofing system would be expected tohave a longer service life.1.5 This guide includes materials used in roofing systemsunder jurisdiction of ASTM Committee D08 on Roofing andWaterproofing.The applicability of this guide to other systemsand materials has not been determined.1.6 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 determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1079 Terminology Relating to Roofing and Waterproofing3.Terminology3.1 GeneralTerms used in this guide are defined inTerminology D1079,except as defined below.3.2 Definitions:3.2.1 design lifethe planned period of time during whichthe roofing system is expected by its designer to reliablyperform its required functions,with minimal unplanned inter-vention.3.2.2 durabilitythe ability of the roofing system to per-form its required functions over a period of time within theenvironment for which it is designed and exposed.3.2.3 service lifethe period of time after installation dur-ing which a roofing system performs its required function(s)with minimal unplanned intervention.4.Summary of GuideNOTE1The sustainable roofing system design process consists of thefollowing,sequential steps:4.1 Identification of Roofing System Demands,FunctionalExpectations,and Site ConstraintsThe designer should de-termine factors,loads,and stresses that the roofing system mustwithstand as well as the impacts the roofing system may haveon the environment the building interacts with.These factorsapply limiting constraints for system and material selection andthe associated installation process.There are also options forsustainable strategies and site and use constraints that willdefine the feasibility of sustainable strategies(for example,availability of sunlight for photovoltaic arrays).4.2 Determination of In-Service Performance Criteria andFunctional ExpectationsThe designer determines perfor-mance criteria and functional expectations of the roofing1This guide is under the jurisdiction of ASTM Committee D08 on Roofing andWaterproofing and is the direct responsibility of Subcommittee D08.24 on Sustain-ability.Current edition approved Feb.1,2017.Published February 2017.DOI:10.1520/D7158_D7158M-17.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 system in response to the in-service roofing system demands,functional options,and site constraints.Performance criteriainclude wind-uplift resistance and fire resistance.4.3 Identification of Candidate SystemsWith the criteriafor in-service performance and functional expectationsestablished,the designer can compile a list of candidatesystems that are capable of meeting the roof designrequirements,and are compat