ASTM D7851-17

Standard Guide for Design of Sustainable, Low-Slope Roofing Systems

SIGNIFICANCE AND USE
5.1 This guide is intended to help the user identify and define demands made upon the roofing system by factors such as weather, climate, and building use, in light of the fact that many roofs are specified with secondary features that have quantifiable or non-quantifiable environmental or humanitarian benefit such as alternative energy generation, vegetation, or use as open space. Awareness of the roof’s use as a platform for these secondary functions, as well as the additional demands they make upon the roof, is needed to specify a durable and sustainable roof.  
5.2 It is the responsibility of the user of this guide to determine the appropriate prescriptive requirements for implementation of the sustainable roofing system based on considerations listed herein.  
5.3 Codes and local ordinances set minimum requirements for roofing systems. Nothing in this guide should be construed to abridge or lessen requirements of codes and local ordinances. Other entities, such as building insurers and system manufacturers, may have requirements for the roofing system.  
5.4 Sustainability of a roofing system is site and use specific. A roofing system considered sustainable for a certain site or application may not be sustainable in a different application. There may also be more than one roofing system that achieves an optimal level of sustainability for a given site and application.  
5.5 Above-roof vegetative (green) systems and rooftop energy generation systems are discussed herein because they are frequently placed on roofs to reduce the building’s overall environmental impact. These features do not generally contribute to the durability or longevity of the roof. These features may be detrimental to roof system performance and impair the roof’s ability to perform its primary function of protecting the building if their impact is not accounted for in the roof design.  
5.6 Design of above-roof systems is beyond the scope of this guide; however, consideration of their p...
SCOPE
1.1 This guide provides guidance and considerations related to designing sustainable low-sloped roofing systems, including exposed membrane roofs, membranes covered with vegetative (green) overburden systems, ballasted roofs, and protected membrane roofing assemblies. A sustainable roofing system minimizes environmental impact, conserves energy, and has maximized service life.  
1.2 The primary purpose of a roofing system is to weatherproof the building’s top surface. Implementing a sustainable roofing system is the intent of this guide.  
1.3 This guide acknowledges that many factors outside the designer’s control affect the longevity of a roofing system. The designer may rely on industry literature (X1.1) and personal experience with roofing systems to estimate the design life.  
1.4 The premise of this guide is to focus attention on environmental and other factors that may affect the roofing system over its service life. By considering these factors and incorporating into the roofing system design certain features that mitigate these factors and their potential adverse effects on the roofing system, the roofing system would be expected to have a longer service life.  
1.5 This guide includes materials used in roofing systems under jurisdiction of ASTM Committee D08 on Roofing and Waterproofing. The applicability of this guide to other systems and materials has not been determined.  
1.6 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Published
• Publication Date: 31-Jan-2017
• ICS: 91.060.20 - Roofs
• Technical Committee: D08 - Roofing and Waterproofing
• Drafting Committee: D08.24 - Sustainability

Relations

• Refers: ASTM D1079-20 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-May-2020
• Refers: ASTM D1079-18 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Dec-2018
• Refers: ASTM D1079-18e1 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Dec-2018
• Refers: ASTM D1079-16 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Feb-2016
• Refers: ASTM D1079-13e1 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Mar-2013
• Refers: ASTM D1079-13 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Mar-2013
• Refers: ASTM D1079-10 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Sep-2010
• Refers: ASTM D1079-09 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Jul-2009
• Refers: ASTM D1079-08a - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Feb-2008
• Refers: ASTM D1079-08 - Standard Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Jan-2008
• Refers: ASTM D1079-07a - Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Jun-2007
• Refers: ASTM D1079-07 - Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Jan-2007
• Refers: ASTM D1079-06 - Terminology Relating to Roofing and Waterproofing
• Effective Date: 01-Aug-2006
• Refers: ASTM D1079-05a - Terminology Relating to Roofing and Waterproofing
• Effective Date: 15-Sep-2005
• Refers: ASTM D1079-05 - Standard Terminology Relating to Roofing, Waterproofing, and Bituminous Materials
• Effective Date: 01-Mar-2005

Overview

ASTM D7851-17: Standard Guide for Design of Sustainable, Low-Slope Roofing Systems provides comprehensive guidance for designing low-slope roofing systems that minimize environmental impact, conserve energy, and achieve maximized service life. Developed by ASTM International, this standard addresses both exposed membrane roofs and roofs with additional features like vegetative (green) systems, ballasted roofs, and protected membrane assemblies.

Low-slope roofing systems are increasingly specified with secondary functions such as rooftop vegetation, alternative energy generation, or recreation spaces. This guide recognizes that sustainable design requires attention to these multi-functional demands while ensuring the primary purpose of any roof - weatherproofing and protection of the building.

Key Topics

Identifying Roofing System Demands

• Environmental and Mechanical Stresses: Assess weather, climate, wind, snow, fire, thermal, water, and impact loads.
• Building Use and Functional Expectations: Consider end-use requirements, service life, and expected maintenance.
• Site Constraints: Factor in local ordinances, building codes, environmental interaction, and available sunlight for energy systems.

Evaluating Sustainability Factors

• Life-Cycle Assessment: Evaluate cradle-to-grave impact, recyclability, and resource use.
• System Durability and Longevity: Select materials with proven long-term performance and minimal maintenance.
• Roof as a Platform: Account for demands from green roofs, solar panels, or other secondary systems-ensuring these do not impair waterproofing.

Ensuring Compliance and Practicality

• Code and Regulation Considerations: Verify all design elements meet or exceed local codes, ordinances, and insurer/manufacturer requirements.
• Customization to Site and Application: Tailor sustainable roofing solutions to specific building operations and environmental contexts.

Applications

ASTM D7851-17 is vital for architects, roofing consultants, builders, and facility managers who aim to incorporate sustainability principles into building envelope design. Practical applications include:

• Commercial and Institutional Buildings: Design of office, retail, education, or healthcare facilities requiring robust, energy-efficient roofing.
• Green Building and LEED Projects: Guidance supports green certifications via energy conservation, use of vegetation, or renewable energy features.
• Roof Replacement and Rehabilitation: Offers protocols for maximizing reuse, recycling, and adaptability when reroofing existing structures.
• Rooftop Energy and Vegetation Installations: Ensures that solar panels or green roofs are properly supported, maintained, and do not compromise building protection.

By following this standard, stakeholders can address service life, environmental impact, local regulations, and emerging demands like rooftop energy generation and stormwater management.

Related Standards

Integrating ASTM D7851-17 with related standards enhances roofing system performance and sustainability:

• ASTM D1079 – Terminology Relating to Roofing and Waterproofing
• FM Global Property Loss Data Prevention Sheet FM 1-35 – Green Roof Systems
• CIB Publications on Sustainable Roofing – International guidance on sustainable low-slope roofing materials and systems
• Local Building Codes – Ensure harmonization of sustainable design with applicable jurisdictional requirements

Additional resources and supplemental guidance can be found through industry organizations such as the Center for Environmental Innovation in Roofing and relevant technical literature.

Keywords: sustainable roofing, low-slope roofing, energy-efficient roofing, vegetative roof systems, rooftop energy generation, ASTM D7851-17, roofing system durability, environmental impact, roofing system maintenance, green building standards.

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: D7851 − 17
Standard Guide for
Design of Sustainable, Low-Slope Roofing Systems
This standard is issued under the fixed designation D7851; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide provides guidance and considerations related
D1079 Terminology Relating to Roofing and Waterproofing
to designing sustainable low-sloped roofing systems, including
exposed membrane roofs, membranes covered with vegetative
3. Terminology
(green) overburden systems, ballasted roofs, and protected
3.1 General—Terms used in this guide are defined in
membrane roofing assemblies. A sustainable roofing system
Terminology D1079, except as defined below.
minimizes environmental impact, conserves energy, and has
maximized service life.
3.2 Definitions:
3.2.1 design life—the planned period of time during which
1.2 The primary purpose of a roofing system is to weather-
the roofing system is expected by its designer to reliably
proof the building’s top surface. Implementing a sustainable
perform its required functions, with minimal unplanned inter-
roofing system is the intent of this guide.
vention.
1.3 This guide acknowledges that many factors outside the
3.2.2 durability—the ability of the roofing system to per-
designer’s control affect the longevity of a roofing system. The
form its required functions over a period of time within the
designer may rely on industry literature (X1.1) and personal
environment for which it is designed and exposed.
experience with roofing systems to estimate the design life.
3.2.3 service life—the period of time after installation dur-
1.4 The premise of this guide is to focus attention on
ing which a roofing system performs its required function(s)
environmental and other factors that may affect the roofing
with minimal unplanned intervention.
system over its service life. By considering these factors and
4. Summary of Guide
incorporating into the roofing system design certain features
NOTE 1—The sustainable roofing system design process consists of the
that mitigate these factors and their potential adverse effects on
following, sequential steps:
the roofing system, the roofing system would be expected to
4.1 Identification of Roofing System Demands, Functional
have a longer service life.
Expectations, and Site Constraints—The designer should de-
1.5 This guide includes materials used in roofing systems
termine factors, loads, and stresses that the roofing system must
under jurisdiction of ASTM Committee D08 on Roofing and
withstand as well as the impacts the roofing system may have
Waterproofing. The applicability of this guide to other systems
on the environment the building interacts with. These factors
and materials has not been determined.
apply limiting constraints for system and material selection and
the associated installation process. There are also options for
1.6 This standard does not purport to address all of the
sustainable strategies and site and use constraints that will
safety concerns, if any, associated with its use. It is the
define the feasibility of sustainable strategies (for example,
responsibility of the user of this standard to establish appro-
availability of sunlight for photovoltaic arrays).
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4.2 Determination of In-Service Performance Criteria and
Functional Expectations—The designer determines perfor-
mance criteria and functional expectations of the roofing
This guide is under the jurisdiction of ASTM Committee D08 on Roofing and
Waterproofing and is the direct responsibility of Subcommittee D08.24 on Sustain- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ability. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Feb. 1, 2017. Published February 2017. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7851-17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7851 − 17
system in response to the in-service roofing system demands, 6. Procedure
NOTE 2—The design process includes the following tasks, shared with
functional options, and site constraints. Performance criteria
prudent design of any roofing system but are included for completeness.
include wind-uplift resistance and fire resistance.
An illustrative flow chart is provided in Appendix X2.
4.3 Identification of Candidate Systems—With the criteria
6.1 Define Roofing System Demands, Functional
for in-service performance and functional expectations
Expectations, End User Requirements, and Site Constraints—
established, the designer can compile a list of candidate
The sustainable roofing design process begins by determining
systems that are capable of meeting the roof design
and analyzing factors including, but not limited to: environ-
requirements, and are compatible with desired sustainable
mental and mechanical stresses that the roofing system will be
features and functional expectations.
subjected to, required functions and the uses of the roof,
sensitivity of local environment to the effects of the roofing
4.4 Evaluation of Candidate Systems—Candidate systems
system, interaction of the roof with the indoor building
are analyzed with respect to each other and with respect to
environment, building use and design life, and site factors that
cradle-to-grave (life-cycle) environmental impacts through an
may affect selection of various sustainable roofing strategies.
environmental life cycle assessment, component recyclability,
Some of these factors may be specified by local building codes
minimization of waste, durability, and anticipated lifespan.
and ordinances but others will require determination on the part
4.5 Design of Optimal Best-Fit Candidate—The best-fit
of the building and roofing system designers. To some degree
candidate system is selected for final design.
the various constraints, demands, and expectations may over-
lap or may fall into more than one category. A partial list of
5. Significance and Use
such considerations includes the following:
6.1.1 Roofing System Demands-Code Driven:
5.1 This guide is intended to help the user identify and
6.1.1.1 Wind Velocity and Exposure,
define demands made upon the roofing system by factors such
6.1.1.2 Fire Risk,
as weather, climate, and building use, in light of the fact that
6.1.1.3 Snow Loads,
many roofs are specified with secondary features that have
6.1.1.4 Live Loads,
quantifiable or non-quantifiable environmental or humanitarian
6.1.1.5 Roof Solar Reflectance and Thermal Emittance,
benefit such as alternative energy generation, vegetation, or use
6.1.1.6 Hail Exposure,
as open space. Awareness of the roof’s use as a platform for
6.1.1.7 Rainfall Rate, and
these secondary functions, as well as the additional demands
6.1.1.8 Thermal Loads/Stress.
they make upon the roof, is needed to specify a durable and
6.1.2 Serviceability Considerations:
sustainable roof.
6.1.2.1 Long-Term Weather Resistance,
5.2 It is the responsibility of the user of this guide to
6.1.2.2 Foot Traffic/In-Service Abuse Level,
determine the appropriate prescriptive requirements for imple-
6.1.2.3 Chemical Exposure,
mentation of the sustainable roofing system based on consid-
6.1.2.4 Building Design Life, and
erations listed herein.
6.1.2.5 Indoor Humidification/Building Pressurization.
5.3 Codes and local ordinances set minimum requirements 6.1.3 End User Requirements:
for roofing systems. Nothing in this guide should be construed 6.1.3.1 Platform for Energy Generation System,
to abridge or lessen requirements of codes and local ordi- 6.1.3.2 Platform for Vegetation,
nances. Other entities, such as building insurers and system 6.1.3.3 Use by People/Planned Habitat for Wildlife, and
manufacturers, may have requirements for the roofing system.
6.1.3.4 Enhanced Thermal Efficiency.
6.1.4 Site Considerations:
5.4 Sustainability of a roofing system is site and use
6.1.4.1 Building Use,
specific. A roofing system considered sustainable for a certain
6.1.4.2 Surface Water Runoff Restrictions, and
site or application may not be sustainable in a different
6.1.4.3 Building Orientation/Latitude/Availability of Sun-
application. There may also be more than one roofing system
light.
that achieves an optimal level of sustainability for a given site
and application. 6.2 Determine Required Physical Properties and Perfor-
mance Criteria—A sustainable roofing system satisfies the
5.5 Above-roof vegetative (green) systems and rooftop
minimum design requirements defined by codes and
energy generation systems are discussed herein because they
ordinances, as well as the functional expectations and accom-
are frequently placed on roofs to reduce the building’s overall
modate site constraints developed in 6.1. Functional expecta-
environmental impact. These features do not generally contrib-
tions may not be dictated by applicable codes. Some functions
ute to the durability or longevity of the roof. These features
are demanded by the end user. Some are determined by the
may be detrimental to roof system performance and impair the
roofing system designer. Some functional expectations, such as
roof’s ability to perform its primary function of protecting the
the roof’s resistance to rooftop traffic, pollutants, and chemical
building if their impact is not accounted for in the roof design.
attack, affect durability and serviceability of the roof. Another
5.6 Design of above-roof systems is beyond the scope of set of criteria limits the roof’s interaction with the local
this guide; however, consideration of their potential impacts is environment and establishes feasibility of various sustainable
outlined herein. roofing options. Some of these criteria, such as surface
D7851 − 17
reflectance, may be prescribed by local ordinance. Other flashing extending beneath the fenestration or door threshold.
criteria are not required to meet minimum requirements and are Edge securement should be specified and detailed to resist
difficult to quantify. Establishing these criteria or features design wind loads.
should be based on a reasonable or qualitative determination of
6.2.2.2 Drainage—Positive slope to the primary drains,
benefit in mitigating the overall impact of the building and its
scuppers, or gutters should be provided for all roofing systems
occupants on the environment. These criteria can include
so that standing water does not remain on the roofing mem-
restoring vegetation displaced by the building footprint through
brane 48 hours after rainfall, when the roof is subjected to
use of rooftop plantings, runoff retention, or making available
ambient drying conditions.
roofing space for alternative energy generation. Examples of
6.2.2.3 Penetrations are unavoidable but should be mini-
performance criteria and functional concepts that address
mized. Penetration pockets should be minimized because they
system demands, functional expectations, and site constraints
typically require more maintenance and pose a higher risk of
include the following:
leakage than durable flashings. In the case of multiple small-
6.2.1 Physical Properties and Performance Criteria to be
diameter penetrating members, such as electrical conduit or
Determined:
refrigerant lines, it is often preferable to house them in a
6.2.1.1 Wind Uplift Resistance,
flashed enclosure that extends above the roof surface, where
6.2.1.2 Fire Resistance,
the penetrating elements can exit through protected openings in
6.2.1.3 Deck Structural Capacity,
the side of the enclosure.
6.2.1.4 Resistance to Heat and UV Exposure,
6.2.2.4 Air Barrier System—Substantial energy loss,
6.2.1.5 High Indoor Humidity/Building Pressurization,
condensation, and resulting damage to roofing components can
6.2.1.6 Hail Resistance Rating, be caused by infiltration or exfiltration of air through the
6.2.1.7 Drainage and Slope Requirements, roofing assembly or roof perimeter conditions. An independent
air barrier system to prevent movement of extraneous air and
6.2.1.8 Foot Traffic Resistance,
moisture into the roofing system should be considered for
6.2.1.9 Chemical Resistance,
buildings with high potential or design humidity and where
6.2.1.10 Required Roof Service Life (should be greater than
pressure differentials that may drive indoor air into the roofing
design life of above-roof components),
system may exist.
6.2.1.11 Resistance to Potential Rooftop Uses, Vegetation,
6.2.2.5 Leak Detection—Water leakage through roofing
and Landscaping Activities (if applicable), and
membranes causes premature deterioration. Early detection of
6.2.1.12 Potential for Moisture Accumulation Within the
leakage can prolong the service life of the roofing system.
Roofing Assembly (considering wintertime membrane tem-
Leakage into roofing systems is often difficult to identify due to
perature based climate, roofing emissivity and reflectance,
water absorption by the insulation, water collection on deck
indoor environment, and presence of vapor and air barriers).
surfaces or vapor retarders, or water directed into concealed
6.2.2 Additional Considerations for Durability and
spaces. Timely identification of leakage provides an opportu-
Maintainability—Given all other considerations of the life
nity for repair before chronic leakage causes systemic damage
cycle analysis and in-service performance being equal, a
to the roofing system. Leakage locations or minor defects, or
durable roofing system, one with greater longevity or extend-
both, that could become leaks are likely to be discovered
able service life through minor (that is, low environmental
during regularly scheduled maintenance programs.
impact) maintenance will use fewer resources, have lower
6.2.2.6 Maintenance Requirements and Plan—The design
environmental impact and will therefore be more sustainable
should include instructions for planned future maintenance and
than a roofing system that requires more-frequent replac
...