Template:ROOFTOP GARDENS, PLANTERS & WALKWAYS (EPDM, TPO)

1 General

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").

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 (1/8") 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 RGC Guarantee Standards and manufacturer’s installation instructions.

Only RGC accepted Thermoset roofing membranes that are specifically accepted by the membrane manufacturer for use on Landscaped and Vegetated (green) roof systems qualify for coverage under the RGC Guarantee Program. The Membrane Manufacturer and RGC 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 specifically not covered under the RGC Guarantee Program or the responsibility of RGC. 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 (1/2") adhered approved RGC 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 200 mm, 8" in depth). Intensive vegetated systems (200 mm, 8" or more in depth) 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.

2.2 Drainage

A drainage layer is required. Specialized proprietary drainage products must be acceptable to the membrane manufacturer.

3 Planter Design & Waterproofing

Non-structural planters placed over landscaped deck and roofing membranes, with an appropriate protection layer, are strongly recommended whenever practical.

4 CSA A123.24 and Wind Uplift

All vegetative roof systems using a modular system are required to meet CSA A123.24 “Standard test method for wind resistance of modular vegetated roof assembly”.

5 Flood Testing

Flood Testing is not a recommended practice but is at the discretion of the design authority or owner on systems permitted by ASTM D5957. If flood testing is required, testing shall be conducted prior to installation of overlying insulation or overburdens and conducted as per ASTM D5957.

6 Overburdens

6.1 Extensive Vegetative Roof Assemblies

Where Extensive Vegetative Roof Assemblies are installed as part of the roofing specification and / or contract (Extensive Vegetative Roof Assemblies are defined as 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) the costs for removal and replacement of soil to access the membrane, to investigate or repair leaks in the membrane, are included in the RGC 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.

6.2 Intensive Vegetative Roof Assemblies

Where Intensive Vegetative Roof Assemblies are installed as part of the roofing specification and/or contract (Intensive Vegetative Roof Assemblies are defined as 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), and where the soil thickness of Intensive Vegetative Roof Assemblies exceeds 200 mm (8″), the removal and replacement of soil and plants to access the membrane to investigate or repair leaks in the membrane is the responsibility of others, and such access shall be paid by others. In addition, the removal and replacement of plants, irrigation lines 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 also the responsibility of others, and such access shall be provided and or paid for by others.

6.3 Planters

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 Section 5 & 9 Construction Drawings, qualify for RGC 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 RGC 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 Section 5 & 9 Construction Drawings, qualify for RGC 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 RGC guarantee. Conventionally insulated roof assemblies are required to have a minimum 12.5mm (1/2") adhered approved RGC 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 200 mm, 8" in depth). Intensive Vegetative Roof Assemblies in excess of 200 mm (8") or more in depth are not permitted over conventionally insulated roof systems.

7 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.

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 RGC guarantee, as is any detrimental effect the materials may have on the roof system.