Elevated Green Roof Systems
‘Extensive’ green roofs are typically defined as having growing media less than 8″ deep, use small, low-growing plant species such as succulents, and require minimal maintenance with relatively low water needs.
A modular tray system filled with 4 inches of growing media and plantings is generally the simplest and most versatile means of creating an ‘extensive’ green roof. But in many cases, there’s a need to elevate the planter trays to cover service pipes, electrical conduits and surface irregularities, to raise the plantings to match the height of paved areas, or to correct for the slope on the rooftop.
Fiberglass grating panels supported by adjustable height pedestals undoubtedly offer the most effective and versatile means of supporting raised planter trays. The fiberglass panels not only provide a solid base for the planter trays but can provide support for pavers set among the plantings – porcelain, stone or concrete. Expanded polystyrene (EPS) foam is combustible and labor-intensive to install while concrete pavers are extremely heavy and may exceed roof loadings with filled planter trays.
Some of the other benefits of using fiberglass grating panels to elevate and support an extensive green roof tray system include:
- less pedestals needed c.f. concrete pavers
- large panel size (typically 4′ x 8′) ensures much faster installation
- superior wind uplift protection – interconnected panels create a continuous surface
- allows space for irrigation pipes under the plantings
- water drains freely via the open grid structure
- minimizes weight loading – just 2.5 – 4 lb/sq.ft. (depending on panel thickness)
Archatrak Extensive Green Roof System
The complete, elevated extensive green roof system uses patented interlocking and overlapping green planter trays that are supported by a fiberglass grid laid over adjustable height pedestals, allowing porcelain, concrete or stone pavers to be easily incorporated in the overall design and set to any desired height relative to the planter trays.
Each function of a layered green roof system is incorporated into the tray system, eliminating the need for separate drainage mats, water retention mats, root barriers, and filter fabric, but ensuring superior stormwater management and ease of installation.
- Stormwater management. Ridges and troughs at the base, capture and slowly release peak stormwater flows via a specific pattern of small drain orifices.
- Healthy, thriving plants. The ridge and trough design promotes the airflow necessary for plant growth and root health by preventing overly saturated media. The metered release of water allows plants ample time to uptake water and nutrients from the growing media without sitting in standing water.
- Interlocking edges. Tray edges overlap, linking the individual trays, which are further secured with pins to create a fully interlocking system. This tray design delaminates lateral wind pressures, thus reducing wind uplift across the entire installation. It also prevents trays from shifting apart, and allows trays to be overfilled with soil for invisible tray lines and a flexible soil depth.
- Environmentally friendly. The tray is made from 88% post-industrial recycled polypropylene.
- Integrated high-efficiency drip irrigation. Can be installed in planted-in-place systems.
For strong, healthy, plant life to thrive on a rooftop, proper drainage and optimal planting capacity is a must. The 4” deep M-Tray® by Wallbarn plays a key role in this aspect of Archatrak’s extensive green roof system. Made from recycled, fire-resistant polypropylene, these easy-to-install planter trays snap together seamlessly to support expansive green space on any elevated deck.
Drainage holes strategically spaced along the bottom of the M-Tray® allow vegetation to absorb rainfall, enhance attenuation and slow discharge. The tapered sides of the container ensure optimal water retention around the edges which avoids yellowing at the borders and evens out the growth-rate of the plantings.
Sized at 19 11/16” x 19 11/16” these trays can be easily carried, positioned, and repositioned by installers. Each tray features 4 grips on the underside for easy handling and each corner at the bottom of the tray is rounded to help eliminate the risk of puncturing any membrane laid below.
Connection brackets supplied with the M-Trays® are made to tighten gaps and hold everything in place. Any remaining space between the trays will be covered in no time once the plants fill in. After installation, maintenance with this modular green tray system is simple. Just remove any individual M-Tray® to access to the subsurface below without disrupting the rest of the deck structure.
Specifications
Type Of Construction: Permanent
Width / Breadth: 19 11/16” x 19 11/16”
Height: 4”
Shape Of Walls / Sides: Tapered / Angled
Material: Recycled Polypropylene
Thickness Of Material: 3mm
Internal Ridge Height / Reservoir Height: ¾”
Number Of Internal Drainage Reservoirs: 25
Drainage Holes Per Unit: 8
Distance Between Trays At Base: ¾”
Dry Weight (Empty): 2.42 lbs
Weight Planted & Saturated: 55.11 lbs (200 psf excluding snow load)
Connectors Per Unit: 4
Number Of Grips On Underside: 4
Detail Of Corners / Edges: Smooth / Reinforced
Fire Classification: B ROOF t(4) tested in accordance with CEN/TS 1187 Test 4.
Fiberglass Composition: Archatrak fiberglass grating panels are manufactured exclusively with pure isophthalic resins – lower cost polyester resins do not offer sufficient long-term durability in harsh exterior conditions.
Grating panels use only aluminum hydroxide filler (not calcium carbonate) for maximum fire resistance (flame retardant and smoke suppression) and contain UV stabilizers.
Thickness: typically 1″ (1 1/2″ thick may be required for walkways)
Load bars: 1 1/2″ x 1 1/2″ on center
Mesh aperture: 1 1/4″ x 1 1/4″
Surface: gritted slip resistant surface
Weight: 2.5 lb/sq.ft. (1″ thick)
Installation: Archatrak supplies Eterno ‘NM’ adjustable height pedestals for supporting fiberglass grating panels which offer support from as low as 1″ to more than 24″.
Panels can be joined together with stainless steel ‘C’ clips to form a continuous grid across the entire area.
Where pavers are being used in conjunction with green roof plantings, pavers should be supported independently of fiberglass gratings, with an additional row of pedestals placed along the transition of grating to pavers, so paver heights can be adjusted to bring their surface level with the top of the planter tray (if required).
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