Template:ROOFTOP GARDENS, PLANTERS & WALKWAYS (SBS)
Template:ROOFTOP GARDENS, PLANTERS & WALKWAYS (SBS)
SBS Modified Bituminous membranes used on Landscaped and Vegetated conventionally insulated roofing systems with an overburden 150 mm (6”) or less in depth shall consist of two plies and the top ply (cap) must be a minimum thickness of 3.7 mm on the selvedge edge, with a minimum 180g / meters squared polyester or equal strength combination reinforcement. Thermoset and Thermo Plastic (EPDM, TPO, PVC) single ply membranes used for Landscaped and Vegetated roofing systems shall be fully adhered and a minimum thickness of 1.5mm (0.060").
- In this Manual, “overburden” denotes any manner of material, equipment or installation that is situated on top of, and covering all or a portion of, a roof or waterproofing membrane assembly. This excludes thermal insulation but includes, and is not limited to,
- planters, inclusive of everything they contain;
- vegetated assemblies in trays, mats or other similar containers;
- loose growing media, gravel, sand or any other granular material;
- non-structural water features, inclusive of the water;
- void fill;
- tiles, pavers, supporting pedestals or other similar materials;
- equipment and/or installations, other than those mounted on curbs or structural mounts which are permanently waterproofed with the roof membrane assembly
- Extensive Vegetated Roof Assemblies
- Roof top gardens having minimal plant species diversity, irrigated only to establish plants, and typically having a soil depth of less than 150 mm or 6 inches.
- Intensive Vegetated Roof Assemblies
- Roof top gardens with diverse plant species, irrigated for maintenance and typically having a soil depth equal to or more than 150 mm or 6 inches.
1.2 Design and Construction Requirements
Roof Systems – Options and Requirements
A conventional roof membrane assembly is not appropriate for all types of roofs supporting overburden. For example, overburden weight, and hydrostatic pressure exerted because of certain types of overburden, demand different materials and design approaches to ensure membranes do not fail. Therefore, where
- the designed overburden of the roof assembly (excluding plants) equals or exceeds 150 mm (6”) in depth, or
- the point-loading of overburden equals or exceeds 138 kPa (20 psi); or
- moveable planters or equipment/installations on a roof each weigh 90 Kg (200 lbs) or more
the roof must be designed and constructed to comply with all the requirements for a Protected Membrane Roof assembly (insulated above the membrane); under these circumstances, conventionally insulated roof assemblies (insulated beneath the membrane) are not permitted under the RoofStar Guarantee Program. Furthermore, both a Moisture Survey Scan of the installed membrane assembly and a permanently installed electric leak detection system are mandatory (for leak detection system requirements, refer to the RoofStar Guarantee Standards for Waterproofing Plazas, Promenades and Terraces). EPDM roof membranes are therefore excluded from these applications.
The cost of removal and re-installation or replacement of any such equipment, installations, planters, overburden (or services and connections associated with them) is the sole responsibility of the building owner, whether for the purpose of investigating a leak or conducting warrantable repairs to the membrane.
|Roof Assembly Type||Overburden characteristics|
|< 90 kg ea.
|= / > 90 kg ea.
|< 138 kPa
|= / > 138 kPa
|< 150 mm
|= / > 150 mm|
|Integrity Scan||Not available for Conventional Roof Systems under the RoofStar Guarantee Program|
|Leak Detection System||Not available for Conventional Roof Systems under the RoofStar Guarantee Program|
|Leak Detection System||Required||Required||Required|
- = Permissible (but not required)
- = Not Permissible
For further requirements concerning leak detection for Rooftop Gardens, Planters & Occupied Spaces, see 10.7 Membrane Moisture Surveys and Electric Leak Detection.
2 Membrane Protection
Protection for roofing membranes is required during the installation and maintenance of landscaping, extensive and intensive vegetated (green) roofing installations. The minimum membrane protection must be installed by the roofing or waterproofing contractor and shall be 3 mm (⅛") asphalt core protection board or 25 mm (1") minimum extruded polystyrene insulation plus filter mat, root intrusion barrier, and drainage layer. Tightly butt all protection and insulation boards, overlap all filter mat seams and seal all laps of roof intrusion barriers to RoofStar Guarantee Standards and manufacturer’s installation instructions.
Only RoofStar-accepted SBS Modified Bituminous, Thermoset and Thermoplastic roofing membranes that are specifically accepted by the membrane manufacturer for use on Landscaped and Vegetated (green) roof systems qualify for coverage under the RoofStar Guarantee Program.
The Membrane Manufacturer and RoofStar Guarantee Program must confirm acceptance of other alternative protection systems or components in writing. Damage to membranes and flashings that results from the use of plants with aggressive root structures, (Bamboo, Willow etc.) for landscaped and green (vegetated) roof systems, is not the responsibility of the RoofStar Guarantee Program and is specifically not covered under the RoofStar Guarantee. For additional information refer to the latest addition of the British Columbia Landscape Standard, Green Roof Section.
Conventionally insulated roof assemblies are required to have a minimum 12.5mm (½") adhered RoofStar-accepted gypsum overlay board, and insulation boards with a minimum compressive strength of 20 psi, under the roof membrane for extensive vegetated systems (with depth less than 150 mm, or 6"). Intensive vegetated systems (with depth equal to or greater than 150 mm, or 6") are not permitted over conventionally insulated roof systems.
2.1 Root Barriers & Separation Zones
Proprietary root intrusion barriers must be acceptable to the roof membrane manufacturer and appropriate for the vegetation system installed. Polyethylene or polypropylene sheeting used as a root barrier shall be a minimum thickness of .2mm (8mils). Root Barriers shall be sheets or boards installed in a continuous plane above the roof membrane, carried up the inside of soil retention perimeters (separation zones), and must be installed with sealed laps and seams as per manufacturer's instructions.
Separation Zones that are free of growing medium and vegetation are required around all roof perimeters, up-stands, drains, penetrations, mechanical equipment, expansion joints, etc. Zones must be a minimum of 300 mm (12”) wide and constructed with curbs or other physical barriers that separate and facilitate drainage. Physical barriers must be placed above the membrane protection layers and must not be attached through or penetrate the roof membrane.
A drainage layer is required. Specialized proprietary drainage products must be acceptable to the membrane manufacturer.
3 Planter Design & Waterproofing
4 CSA A123.24 and Wind Uplift
All vegetated roof systems using a modular system are required to meet CSA A123.24 “Standard test method for wind resistance of modular vegetated roof assembly” (latest edition).
5.1 Extensive Vegetated Roof Assemblies
Where Extensive Vegetated Roof Assemblies are installed as part of the roofing specification and / or contract, the costs for removal and replacement of soil to access the membrane, to investigate or repair leaks in the membrane, are included in the RoofStar Guarantee coverage. However, the removal and replacement of plants, irrigation lines and or equipment, electrical lines, landscape and decorative features such as concrete pads, statues, planters, large rocks, etc., to investigate or repair leaks in the membrane, is not included, and is the responsibility of others. Subsequently, such access shall be provided and/or paid for by others.
5.2 Intensive Vegetated Roof Assemblies
Intensive Vegetated Roof Assemblies installed as part of the roofing specification and/or contract are permitted on conventionally insulated membrane roof assemblies provided the depth of the growing medium does not exceed 150 mm (6″).
When an Intensive Vegetated Roof Assemblies with growing medium greater than 150 mm (6”) forms part of the roofing specification and/or contract, the roof must be designed and constructed to the RoofStar Guarantee Standards for a Protected Membrane Roof assembly (see 10.1.2 above). Consequently, the removal and replacement of such overburden is the responsibility of the others, and such costs do not form part of the coverage under a RoofStar Guarantee.
Structural planters that incorporate pre-curb or start-up curbs for walls that are completely sealed with membrane and are a minimum of 100 mm (4") in height, as detailed in Construction Detail D1.7.6-5 Curbs & Sleepers (Pre-curb for Planters), qualify for RoofStar Guarantee coverage. Waterproofing liners in planters with structural walls, concrete curb or other materials, that do not incorporate pre-curbs shall be isolated and separated from the guaranteed roofing membrane and are specifically not accepted under the RoofStar Guarantee.
Non-structural planters placed over landscaped deck and roofing membranes, with an appropriate protection layer, are strongly recommended whenever practical. Structural planters that incorporate pre-curb or start-up curbs for walls that are completely sealed with membrane and are a minimum of 100 mm (4") in height, as detailed in D1.7.6-5 Curbs & Sleepers (Pre-curb for Planters), qualify for RoofStar Guarantee coverage.
Waterproofing liners in planters with structural walls, concrete curb or other materials, that do not incorporate pre-curbs shall be isolated and separated from the guaranteed roofing membrane and are specifically not accepted under the RoofStar Guarantee. Conventionally insulated roof assemblies are required to have a minimum 12.5mm (½") adhered approved RoofStar-accepted gypsum overlay board, and insulation boards with a minimum compressive strength of 20 psi, under the roof membrane for extensive vegetated systems (less than 150 mm, 6" in depth). Intensive Vegetated Roof Assemblies in excess of 150 mm (6") or more in depth are not permitted over conventionally insulated roof systems.
6 Walkways and Warning Zones
When primary roof membranes of contrasting colour are used for warning zones, membrane end lap off sets and ply side lap directions must be maintained. Staggered membrane end lap offsets may be positioned below primary roof membranes that are used for warning zones.
Where walkways are employed, they must be designed to facilitate drainage of water. To promote drainage, use accepted concrete-topped XPS insulation panels, or pavers located on purpose-made pedestals. When pavers are used as the walkway material, they must be spaced no closer than 3mm (1/8″) and must be supported by non-abrasive pads or proprietary pedestals providing a minimum of 12.5 mm (1/2″) of vertical separation layer for airflow and levelling. The choice of pedestal or drainage layer type is the responsibility of the design authority. Pedestals provide airflow for drying surfaces and assist in leveling. They should not impede the flow of water or air, and should uniformly distribute the dead load of pavers and predicted live loads.
A design authority or membrane manufacturer may specify a proprietary walkway protection system or warning zone membrane over the primary roof membrane. Walkway and warning zone materials are not part of the roofing membrane assembly but are typically accessory products that are placed over completed roof membranes. Subsequently the type and performance of any walkway or warning zone material is specifically excluded from coverage under the RoofStar Guarantee, as is any detrimental effect the materials may have on the roof system.
7 Membrane Moisture Surveys and Electric Leak Detection
A Membrane Moisture Survey and permanently installed electric leak detection system is mandatory for all roofs that must be designed and installed to meet the requirements for a RoofStar Guaranteed Protected Membrane Roof assembly (see 10.1).
7.2 Flood Testing
Flood Testing is not a recommended practice but is at the discretion of the design authority or owner. If flood testing is required to water test waterproofing membranes, testing shall be conducted prior to installation of insulation and overburdens and be performed to ASTM D5957 - 98.
7.3.1 Moisture Scan Survey
- Membrane moisture survey scans must be performed on all waterproofing membrane systems by an independent Moisture Detection Company that is specifically accepted by the RoofStar Guarantee Program.
7.3.2 Leak Detection Systems
Only electric leak detection systems (utilizing high or low voltage) accepted for use in the RoofStar Guarantee Program may be installed and monitored on waterproofing systems designed and accepted by the RoofStar Guarantee Program.
A Membrane Moisture Survey and an installed electric leak detection system is not required on PMR or MPMR roof systems when the roof system is designed and constructed with
- overburden not exceeding 150 mm (6”) in depth, or
- moveable planters or equipment/installations on a roof each weighing less than 90 Kg (200 lbs); or
- standard concrete pavers on pedestals
Regardless of the accepted leak detection technology employed, the leak detection system must provide detection capabilities for the entire affected deck surface and extend leak detection a minimum of 50 mm (2") vertically from the water plane at
- all transitions;
- any point along the entire deck perimeter; and at
Where the electric leak detection system of choice utilizes a sensor ribbon installed on the waterproofing membrane in a grid pattern, the ribbon spacing shall be no less than two (2) metres in any direction for waterproofing systems covered by the Overburden.
7.4 Leak Detection for Sensitive Occupied Spaces
Designers are strongly encouraged to consider specifying an insulated (PM) membrane system and mandatory leak detection protection for a RoofStar Guarantee when the occupied space below a roof area contains, or will contain,
- highly sensitive equipment or contents (e.g. hospitals, art galleries), or
- electronic systems (e.g. communications or data centres)
Criteria for evaluating the sensitivity of building interiors is left to the Design Authority.