1 Scope
NOTE This standard covers the design and installation of complete vegetated (green) roof assemblies, comprising every layer above the structural deck's primary waterproofing plane: root resistance, protection, drainage and retention, filtration, engineered growing medium, and plant material. (1.1)
NOTE A vegetated roof is an engineered, multi-layer system, not landscaping placed on a roof. Each layer performs a distinct hydraulic, structural, or horticultural function, and the layers must be selected as a coordinated, warranted assembly. The growing medium is engineered mineral soil, not topsoil, and the drainage and filtration layers exist to keep that medium from clogging the roof drains and from drowning the plants. (1.2)
NOTE Three assembly types are addressed, distinguished by growing-medium depth and by the structural load, plant palette, irrigation need, and maintenance burden that follow from it. (1.3)
NOTE Extensive assemblies use growing medium ≤6 in. deep, are typically planted with drought-tolerant sedum and succulents, and are unoccupied except for maintenance access. (1.3.1)
NOTE Semi-intensive assemblies use 6-10 in. of medium, support perennials and ornamental grasses, and generally require supplemental irrigation. (1.3.2)
NOTE Intensive assemblies use more than 10 in. and up to 48 in. of medium, support shrubs and trees, function as occupied green space or plaza/podium deck, and require permanent irrigation and active horticultural maintenance. (1.3.3)
NOTE This standard applies to low-slope roofs at or below 15% (8.5°) slope, to modular tray systems and built-in-place assemblies, and to both new construction and roof replacement. (1.4)
NOTE The base waterproofing membrane below the vegetated assembly is specified under
Membrane Roofing or
Fluid Applied Waterproofing; this standard specifies the root-resistance and protection requirements imposed on that membrane and all layers above it.
(1.5) NOTE Roof edge conditions, copings, and expansion joints are specified under
Roof Specialties And Copings. Site-level subdrainage that receives roof runoff is specified under
Subdrainage, and at-grade planting soil import and grading under
Site Clearing.
(1.6) NOTE Structural design of the deck and framing to carry green roof loads is governed by the structural drawings and ASCE 7; this standard specifies the imposed dead and live loads for coordination only and does not size structural members. (1.7)
2 Referenced Standards
2.1Materials, assemblies, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a more recent edition is mandated by the authority having jurisdiction.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE ASTM E2777 is the umbrella guide for vegetative roof systems; an ASTM revision (work item WK94236) was in progress at the time of writing, so confirm the current edition at the time of specification. The FLL Guidelines remain the de-facto international reference for root-penetration resistance and growing-media composition, and many North American products carry FLL certification as their primary proof of root resistance. (2.3)
| Standard |
Title |
| ASTM E2777-20 |
Standard Guide for Vegetative (Green) Roof Systems |
| ASTM E2400/E2400M-19 |
Standard Guide for Selection, Installation, and Maintenance of Plants for Vegetative (Green) Roof Systems |
| ASTM E2396/E2396M-19 |
Standard Test Method for Saturated Water Permeability of Granular Drainage Media (Falling-Head Method) |
| ASTM E2397/E2397M-19 |
Standard Practice for Determination of Dead Loads and Live Loads Associated with Vegetative (Green) Roof Systems |
| ASTM E2399/E2399M-19 |
Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems |
| ASTM E2788/E2788M-24 |
Use of Expanded Shale, Clay, and Slate (ESCS) as a Mineral Component in Growing Media |
| ASTM D8014-17(2025) |
Standard Guide for Selection of Membranes Used in Vegetative Roofing Systems |
| ASTM D7877 |
Electronic Methods for Detecting and Locating Leaks in Waterproofing Membranes |
| ANSI/SPRI VF-1-2023 |
External Fire Design Standard for Vegetative Roofs |
| ANSI/SPRI RP-14 |
Wind Design Standard for Vegetative Roofing Systems |
| FLL Guidelines 2018 |
Guidelines for the Planning, Construction and Maintenance of Green Roofing (FLL) |
| IBC 2021 |
International Building Code (Section 1507.16, Vegetative Roofs) |
| ASCE 7-22 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Section 4.8) |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following action submittals for review before fabrication, ordering, or installation of any assembly component:
- Product data for each assembly layer: waterproofing/root barrier, protection sheet, drainage/retention layer, filter fabric, growing medium, and edge restraints.
- Shop drawings showing the full assembly section at field, perimeter, penetrations, drains, scuppers/overflows, curbs, and expansion joints, with layer thicknesses and ballast/anchor zones.
- A growing-medium laboratory analysis: gradation, organic content by volume, pH, and saturated bulk density per ASTM E2399.
- A structural-load summary stating the saturated dead load and design live load per ASTM E2397, for the Engineer of Record's confirmation against deck capacity.
- The named, tested fire-classified assembly per ANSI/SPRI VF-1 matching the specified membrane, medium depth, and plant species.
- The wind-uplift design per ANSI/SPRI RP-14 for the project wind zone, including perimeter and penetration anchor/ballast details.
- A planting plan and plant schedule identified by species, form (mat, plug, cutting, or container), and quantity per ASTM E2400.
- The irrigation design, where irrigation is specified, including backflow prevention and drainage outlet.
- The flood-test (electronic leak survey) report for the base waterproofing, completed and accepted in writing before overburden installation begins.
☐ Product data (each assembly layer)
☐ Assembly shop drawings (field, perimeter, penetrations, drains)
☐ Growing-medium lab analysis (gradation, organic, pH, density)
☐ Structural-load summary (ASTM E2397)
☐ Named VF-1 fire-classified assembly
☐ Wind-uplift design (ANSI/SPRI RP-14)
☐ Planting plan and plant schedule (ASTM E2400)
☐ Irrigation design with backflow prevention
☐ Flood-test / electronic leak survey report (before overburden)
3.2.1The Contractor shall submit the following informational submittals:
- Manufacturer certification of root-penetration resistance for the waterproofing membrane (or separate root barrier) per FLL or ASTM D8014.
- ESCS mineral-component certification per ASTM E2788 where ESCS aggregate is used in the growing medium.
- The qualifications of the installer and of the green-roof system manufacturer's field representative.
- The maintenance and plant-establishment plan, including supplemental irrigation duration.
☐ Root-resistance certification (FLL or ASTM D8014)
☐ ESCS component certification (ASTM E2788)
☐ Installer and field-representative qualifications
☐ Maintenance and plant-establishment plan
3.3 Closeout Submittals
3.3.1The Contractor shall submit the following closeout submittals before Substantial Completion:
- The post-installation electronic leak survey (EFVM) report confirming membrane integrity after overburden placement.
- Record drawings of the as-built assembly, including drain and overflow locations.
- Written assembly and plant-establishment warranties.
- The operation and maintenance manual, including the irrigation schedule and seasonal maintenance tasks.
☐ Post-installation EFVM survey report
☐ As-built record drawings
☐ Assembly and plant-establishment warranties
☐ Operation and maintenance manual
4 Quality Assurance
4.1 Qualifications
4.1.1The vegetated roof assembly shall be furnished as a single-source, tested, and warranted system from one manufacturer, including the root-resistant waterproofing (or root barrier), drainage layer, filter fabric, and growing-medium specification.
NOTE Specifying the waterproofing membrane and the vegetated overburden from different manufacturers without a tested, warranted combined assembly invalidates both the ANSI/SPRI VF-1 fire classification and the membrane warranty, because neither was tested in the as-built stack. (4.1.2)
4.1.3The installer shall have completed at least three vegetated roof projects of comparable assembly type and area, and shall install under the periodic observation of the system manufacturer's field representative.
4.1.4The growing medium shall be supplied by a producer who furnishes batch laboratory analysis traceable to the delivered material.
4.2 Mockups and Pre-Installation
4.2.1A pre-installation conference shall be held with the Contractor, waterproofing installer, vegetated-roof installer, structural Engineer of Record, and manufacturer's representative to confirm load assumptions, leak-detection protocol, and sequencing.
4.2.2The base waterproofing shall be flood-tested or electronically surveyed and accepted in writing before any protection, drainage, or growing-medium layer is placed.
5 Environmental and Service Conditions
5.1 Loads
5.1.1Growing-medium dead load shall be calculated using the maximum saturated bulk density determined per ASTM E2399, not the dry or as-delivered density.
NOTE Calculating dead load from dry bulk density underestimates the imposed structural load by 30-50%, because the engineered medium holds substantial water at field capacity. This is a frequent source of structural RFIs when the Engineer of Record's loading assumption differs from the medium actually specified. (5.1.2)
5.1.3The design saturated dead load and the design live load shall be determined per ASTM E2397 and transmitted to the Engineer of Record for confirmation against deck capacity.
5.1.4The design live load for unoccupied landscaped roofs shall be not less than 20 psf per ASCE 7-22 Section 4.8 and IBC 2021 Section 1607.12.3, in addition to the saturated dead load.
● Extensive (growing medium ≤6 in., unoccupied)
○ Semi-intensive (6-10 in., perennials/grasses)
○ Intensive (>10–48 in., occupied / plaza / podium)
5.2 Slope and Climate
5.2.1The standard assembly shall be limited to roof slopes at or below 15% (8.5°) per ASTM E2777.
5.2.2Slopes between 15% and 33% shall incorporate anti-erosion measures and substrate anchors to prevent down-slope migration of the growing medium.
5.2.3The plant palette shall be selected for the roof microclimate, accounting for high heat, wind exposure, and reflected UV from adjacent walls, per ASTM E2400.
NOTE Specifying species unsuited to the roof microclimate is a leading cause of plant failure, and because plant loss triggers warranty inspections that route back to the waterproofer, palette selection is a waterproofing-warranty concern, not only a horticultural one. (5.2.4)
6 Waterproofing Root Resistance and Protection
6.1 Root Resistance
6.1.1The waterproofing assembly below the vegetated overburden shall resist root penetration over the service life of the assembly, either through an inherently root-resistant membrane or through a dedicated root barrier installed above a non-root-resistant membrane.
6.1.2Root resistance shall be achieved by one of two strategies: an inherently root-resistant membrane, or a dedicated root barrier installed above a non-root-resistant membrane.
NOTE An inherently root-resistant membrane is a single layer that both waterproofs and resists root penetration — for example modified bitumen with a metallized (e.g. copper-foil) barrier layer certified per FLL or ASTM D8014, FLL-certified TPO or PVC, or HDPE. A separate root barrier is an added layer (PVC or HDPE sheet) installed above a membrane that is not itself root resistant. (6.1.3)
6.1.4The selected root-resistance strategy shall be certified by root-penetration testing per the FLL Guidelines or ASTM D8014 for the specific membrane or barrier product furnished.
NOTE Specifying a generic membrane without FLL or ASTM D8014 root-penetration certification exposes the owner to undetected root intrusion over the 20-plus-year assembly life, by which time remediation requires removing the entire overburden. (6.1.5)
6.1.6Where a separate root barrier is used, it shall be PVC or HDPE not less than 0.8 mm thick, with seams lapped not less than 6 in. and joined by heat weld or solvent bond.
● Inherently root-resistant membrane (single layer)
○ Compliant membrane plus separate root barrier
● FLL Guidelines root-penetration test
○ ASTM D8014 membrane selection guidance
○ PVC sheet, ≥0.8 mm
● HDPE sheet, ≥0.8 mm
6.2 Protection and Leak Detection
6.2.1A protection layer or slip sheet shall be installed over the waterproofing (and root barrier, if separate) to shield it from mechanical damage during drainage-layer and growing-medium placement.
6.2.2The base waterproofing shall be flood-tested under ponded water for not less than 24 hours before any overburden is placed, or shall be surveyed by an electronic leak-detection method per ASTM D7877.
6.2.3An electronic leak-detection survey (Electronic Field Vector Mapping, EFVM) per ASTM D7877 shall be performed both before overburden installation and after the assembly is complete where the vegetated roof is over occupied space.
NOTE Over occupied space, leak detection is not optional: once overburden is placed, a leak cannot be located without removing the assembly above it, so a before-and-after electronic survey is the only practical safeguard against tearing out a planted roof to find a pinhole. (6.2.4)
○ 24-hour flood test only
● Electronic leak survey (EFVM) before overburden
○ Electronic leak survey (EFVM) before and after (over occupied space)
7 Drainage and Retention Layer
NOTE A drainage and retention layer shall be installed above the protection layer to convey excess water to the roof drains while retaining water for plant use. (7.1)
NOTE The drainage layer is the hydraulic core of the assembly: it must shed water fast enough to prevent the growing medium from becoming saturated and overloaded, while retaining enough moisture between rain events to sustain the plants. These two demands are met by aggregate, by prefabricated drainage composites, or by modular trays with an integral reservoir. (7.2)
7.3The hydraulic conductivity of the drainage layer shall exceed that of the growing medium and shall be not less than 0.02 in./sec (approximately 50 mm/min).
7.4Granular drainage media, where specified, shall be qualified for saturated water permeability per ASTM E2396.
7.5A filter fabric shall separate the growing medium from the drainage layer to prevent fines from migrating into and clogging the drainage course.
NOTE Sizing the assembly without checking that the drainage layer is more permeable than the growing medium inverts the design: water then perches in the medium, raising the saturated weight and drowning roots. The conductivity check is the single most important hydraulic verification in the assembly. (7.6)
○ Granular aggregate drainage course (ASTM E2396)
● Prefabricated HDPE cup drainage composite
○ Prefabricated polystyrene drainage composite
○ Modular tray with integral reservoir
0.020.2
Default: 0.02 in/sec
● Nonwoven geotextile filter fabric
○ Integral filter sheet (part of drainage composite)
8 Growing Medium
NOTE The growing medium shall be an engineered mineral blend, not natural topsoil or compost-heavy garden soil. (8.1)
NOTE Engineered green-roof medium is dominated by lightweight mineral aggregate - expanded shale, clay, or slate (ESCS), pumice, or crushed lava - amended with a limited fraction of organic matter. Topsoil and compost-rich mixes are forbidden because they are heavy when saturated, settle severely as the organics decompose, and drift in pH over time. (8.2)
8.3The mineral component, where expanded shale, clay, or slate (ESCS) is used, shall comply with ASTM E2788.
8.4The growing-medium pH shall be maintained within 6.0 to 8.5 per the FLL Guidelines and manufacturer requirements.
8.5The maximum organic content by volume shall not exceed 20% for extensive and semi-intensive media, and shall not exceed 25% for intensive media.
NOTE Excessive organic content causes the medium to lose 20-30% of its volume over five years as the organics decompose, which settles the planted surface, drifts the pH, and increases retained water and therefore structural load - the opposite of the lightweight, stable medium the assembly requires. (8.6)
8.7The saturated bulk density of the growing medium shall be established by laboratory test per ASTM E2399 and shall be the basis for the dead-load calculation.
● Expanded shale/clay/slate (ESCS), ASTM E2788
○ Pumice-based mineral blend
○ Crushed lava (scoria) mineral blend
9 Plant Material and Establishment
NOTE The plant palette shall be selected and established per ASTM E2400 for the assembly type, growing-medium depth, and roof microclimate. (9.1)
NOTE Plant material is furnished and established by one of several methods, which differ in establishment time, cost, irrigation demand, and warrantable coverage. Pre-grown sedum mats give near-immediate cover at the highest cost; plugs and broadcast cuttings are cheaper but take weeks to knit; seed mixes are cheapest but slowest and least predictable. (9.2)
9.3Extensive assemblies shall be planted with drought-tolerant species - typically sedum and other succulents - selected to survive without permanent irrigation once established.
9.4Supplemental establishment irrigation shall be provided for extensive sedum assemblies for not less than the period required to establish root cover, typically 4 to 8 weeks, even in northern climates.
NOTE Omitting establishment irrigation for extensive assemblies is a common and costly error: sedum cuttings and plugs need several weeks of supplemental water to root, and without it plant-loss rates exceed 50% and trigger warranty replacement and re-inspection. (9.5)
9.6The specified coverage and survival rate shall be verified at the end of the establishment period before the plant-establishment warranty period begins.
● Pre-grown sedum mats (roll-out)
○ Sedum plugs
○ Broadcast sedum cuttings
○ Plug and seed mix (semi-intensive)
○ Container plants (intensive)
10 Irrigation
NOTE The irrigation strategy shall match the assembly type: none for established drought-tolerant extensive assemblies, temporary establishment-only drip for marginal extensive and semi-intensive assemblies, and permanent drip or spray for intensive and occupied decks. (10.1)
10.2Where any irrigation is provided, the system shall include backflow prevention in accordance with the plumbing code and a drainage outlet that discharges to the roof drainage system.
10.3Permanent irrigation shall be provided for intensive assemblies and occupied plaza or podium decks, where the plant palette and use cannot be sustained by rainfall alone.
● None (established drought-tolerant extensive)
○ Temporary establishment-only drip
○ Permanent drip irrigation
○ Permanent spray irrigation
11 Edge Restraint, Wind, and Fire
11.1 Wind Resistance and Edge Restraint
11.1.1The assembly shall be designed for wind uplift per ANSI/SPRI RP-14 for the project wind zone, including the perimeter, corners, and the zones around penetrations.
11.1.2A perimeter ballast strip or equivalent wind-uplift anchor zone, not less than 4 in. wide of washed aggregate or pavers, shall be provided at roof edges and around penetrations.
11.1.3Edge restraint shall retain the growing medium and drainage layer at all free edges, drains, and penetrations, by ballasted gravel strip, concrete pavers, or mechanical edge clips as required by the wind design.
NOTE Omitting a perimeter ballast or anchor zone at edges and penetrations violates ANSI/SPRI RP-14 and creates a foreign-object-debris hazard, because the unballasted perimeter is exactly where uplift scours loose medium and lightweight components off the roof. (11.1.4)
● Washed aggregate ballast strip (≥4 in. wide)
○ Concrete paver border
○ Mechanical edge clips / restraint
11.2 Fire Resistance
11.2.1The vegetated roof assembly shall achieve a fire-spread classification per ANSI/SPRI VF-1-2023, as required by IBC 2021 Section 1507.16, for the specific membrane, growing-medium depth, and plant species actually specified.
NOTE The fire classification applies to the assembly as a tested combination. A Class A rating earned by one membrane and sedum mix does not transfer to a different membrane, a deeper medium, or a taller plant palette - the submitted assembly must name the tested combination that matches the construction. (11.2.2)
11.2.3Wood blocking, curbs, and nailers in contact with the vegetated assembly shall be fire-retardant-treated (FRT) lumber in accordance with IBC 2021 Section 1507.16.
NOTE Substituting standard untreated blocking at curbs and nailers is a code violation, not merely a durability concern, because IBC 1507.16 explicitly requires FRT lumber where wood contacts the vegetated assembly. (11.2.4)
● Class A
○ Class B
○ Class C
● Fire-retardant-treated (FRT) lumber
○ Non-combustible curb (no wood in contact)
12 Drainage Coordination at Drains and Overflows
12.1Roof drains, scuppers, and overflows shall be sized and set to account for the added flow resistance of the growing medium and drainage layer, and shall remain accessible for inspection through the overburden.
NOTE A vegetated roof slows peak runoff, which is its purpose, but during extreme events the assembly can surcharge the drains; overflow and scupper invert elevations must be set above the assembly depth so the roof can shed water before it ponds onto the medium. (12.2)
12.3Drain locations, scupper and overflow elevations, and inspection-chamber locations are arrangement decisions fixed by the roof plan and shall be taken from the drawings: roof drain and overflow plan. 12.4Each roof drain shall be fitted with an inspection chamber or drain-access box that holds the growing medium and filter fabric back from the drain body and permits inspection without disturbing the planting.
13 Installation
13.1The assembly shall be installed in the layer sequence established by the manufacturer's tested assembly: protection layer, root barrier (if separate), drainage/retention layer, filter fabric, growing medium, then plant material.
13.2The base waterproofing shall be inspected, flood-tested or electronically surveyed, and accepted in writing before any overlying layer is installed.
13.3Growing medium shall be placed and lightly consolidated to the specified compacted depth, measured after settlement, and shall not be placed when frozen or saturated.
13.4Drainage composites, filter fabric, and root barriers shall be lapped in the direction of drainage and at the laps specified by the manufacturer, with no gaps at penetrations, drains, or edges.
13.5Foot and equipment traffic over the completed waterproofing shall be controlled and protected during installation to prevent puncture.
13.6Material shall be distributed to avoid concentrated construction loads exceeding the design live load.
14 Delivery, Storage, and Handling
14.1Growing medium shall be delivered in a manner that protects it from contamination and excess moisture.
14.2Growing medium shall be stored off the membrane on protected staging until placed.
14.3Pre-grown vegetated mats and trays shall be installed within the manufacturer's stated shelf life after delivery and shall be kept moist and shaded until placed.
14.4Drainage composites, filter fabrics, and root barriers shall be stored protected from prolonged UV exposure and physical damage in accordance with the manufacturer's instructions.
14.5Concentrated staging of growing medium or trays on the roof shall be distributed so that no point load exceeds the structural design live load confirmed by the Engineer of Record.
15 Warranty
15.1The waterproofing and vegetated assembly shall be furnished under a combined, single-source manufacturer warranty covering watertightness of the membrane and the integrity of the overburden assembly for the specified term.
15.2A plant-establishment warranty shall guarantee the specified plant coverage and survival rate through at least one full growing season following acceptance, with replacement of failed plant material.
15.3The combined assembly warranty and the plant-establishment warranty shall be issued in writing and shall name the tested assembly to which the fire and wind classifications apply.
○ 10 years
○ 15 years
● 20 years
● One growing season
○ Two growing seasons
16 Maintenance
16.1A maintenance plan shall be provided defining seasonal tasks: weeding of volunteer species, replacement of failed plants, inspection and clearing of drains and drain-access boxes, and inspection of perimeter ballast and edge restraints.
16.2Maintenance access shall be provided to all drains, overflows, and edge zones without traversing or compacting planted medium, by maintenance walkways or paver paths where the assembly area or plant fragility warrants.
16.3Intensive and occupied assemblies shall include a horticultural maintenance schedule and irrigation-system servicing consistent with ASTM E2400.
17 Spare Parts
17.1Reserve growing medium and reserve plant material of the specified blend and species shall be delivered to the Owner for establishment-period replacement and minor repairs.
17.2Spare drainage-composite and filter-fabric stock matching the installed products shall be delivered to the Owner for future penetration repairs and patch work.
☑ Reserve growing medium (matching blend)
☑ Reserve plant material (matching species)
☐ Spare drainage composite
☐ Spare filter fabric