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INTENSIVE ROOF GARDENS
WHAT IS
AN INTENSIVE ROOF GARDEN:
The profile is deeper, between 200 – 1200mm. This allows a greater diversity
of plants to be grown, from turf to trees and are generally used as recreational
spaces. These roof gardens place a large amount of weight on a building roof
and require regular maintenance as per a normal garden. This is the current standard
type of roof garden/planter box in Australia. |
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THE FYTOGREEN ROOF GARDEN SYSTEM
The “magic” of the system is
the lightweight water retentive substrate called Hydrocell RG30.
This remarkable material makes possible the construction of a
long lasting lightweight, water storing, efficient roof garden.
Hydrocell RG30 is a foamed aminoplast resin that can either be
manufactured onsite or delivered in pre fabricated sheet form in
60mm and 100mm thick options, or made as a special RG30 flake for
extensive roof gardens and planter boxes which can be applied using
1 m3 bulka bags.
The RG30 Hydrocell layer replaces the traditional heavy sand filter
layer in intensive roof gardens and contributes part of the growing
media on extensive roof gardens. Hydrocell is lighter in weight,
increases usable media volume, and has significantly higher water
and nutrient holding capacity. It also acts as a capillary mat
returning water to the topsoil and acts as a fines filter protecting
the geofabric layer and improving the quality of the storm water.
FYTOGREEN’S INTENSIVE ROOF GARDEN PROFILE
ROLE OF THE VARIOUS LAYERS IN THE PROFILE
Waterproof membrane:
The building roof must have a sealed waterproof layer installed
before work on the roof garden begins. This is commonly called “tanking” and
is installed and certified independently.
LDPE Sheet: This is an extra waterproof sheet, which acts as a
protection layer both from water and plant roots for the waterproof
membrane layer.
Drainage Cell: Critical in allowing excess water to escape the
roof garden profile quickly to the drainage outlets. This reduces
the potential rooftop load issues from ponding water.
Geofabric layer: This minimizes fine soil particles from reaching
the drainage system.
Hydrocell RG30: A 60mm or 100mm layer is used as a fines filter
to protect the geofabric layer. Hydrocell RG30 provides a significant
water reservoir layer holding up to 80 litres per m2 yet only having
a total saturated weight of 84kg per m2. Hydrocell RG30 also increases
usable media volume (enabling thinner profiles), reducing rooftop
weight while at the same time increasing stored water reserves
for plant use and making it available to the soil above via it’s
capillary properties. Hydrocell RG30 has a high compressive strength
enabling large topsoil profiles and lasts up to 25 years
Hydrocell 40 Lightweight Soil Mix: The 40% Hydrocell flake component
is lightweight and holds plant available water throughout the profile.
Hydrocell also has a component of air, which helps the profile
to drain quickly.
50% Coarse or washed sand is “open” allowing good
drainage and offers stability as a soil particle. 10% Composted
Organic Matter offers nutritional value without risking slumping
(lowering of the profile) caused by plants consuming the organics.
ADVANTAGES OF FYTOGREEN’S INTENSIVE ROOF GARDEN SYSTEM
- Huge water holding while saving weight. Hydrocell RG30 layer,
when applied as a 100mm deep layer has a maximum water retention
capacity of 80 litres of water per m2. Equivalent in weight to
50mm layer of dry coarse river sand per m2 with no water available
for plants.
- Lightweight, which offers more flexibility for lower load construction
of buildings.
- High water holding capacity and increase in usable media volume
enabling lower soil profiles.
- Grey water and storm water compatible with no toxicity or harmful
effects to the environment. Hydrocell is biodegradable and non-flammable.
- Durable even under extreme climatic condition giving a longer
life.
- Water Efficiency is increased. The excellent capillary properties
of Hydrocell ensure improved availability of water to plant roots.
- Easy to install with numerous working examples.
- Stable long lasting system designed to be around for a minimum
of 25 years.
WHY USE HYDROCELL RG30:
- Increased Longevity up to at least 25 years
- Increased Water Holding Capacity
- Improved Compressive Strength for foot traffic conditions
MINIMUM ROOF LOAD
Fytogreen's roof garden system is light in comparison with other
systems. This makes possible the construction of a roof garden
on a lower load bearing structure. Fytonop 20 drainage cell weighs
2kg per m2, 100mm of saturated Hydrocell RG30 weighs 84kg per
m2, and 100mm soil mix comprising 40% Hydrocell flake and 50%
washed sand & 10% composted organics has a saturated weight
of 130kg per m2. Lightweight soil mixes are supplied in a range
of configurations, with saturated weights from 900-1300kg per
m2.
INSTALLATION PROCEDURE
Laying the system is a specialized job. Great care must be taken
to avoid damaging the underlying waterproofing. The system is
laid in the following order over the pre-installed water proofing
layer.
- LDPE Sheet
- Fytonop 20 drainage cell
- Geofabric layer - Bidim A14G
- Hydrocell RG30 - water retentive substrate layer
5 Root anchor netting (Only for trees > 3m at time of
planting - allow 4-6 square metres per root ball. Placed directly
under the rootball extending up to 1m either side)
6 Soil mix- Hydrocell 40 lightweight soil
7. Mulch and Plant as a normal garden
PLANT SELECTION:
With an intensive roof garden, opportunities are far greater for
plant selection due to profile depth and moisture availability.
Anything from ground covers/native grasses to trees with the
potential to grow up to 20m in height.
MAINTENANCE AND IRRIGATION:
An intensive roof garden will require an irrigation system, with
the ability to link to rainwater and storm water tanks, the system
can be completely sustainable. Maintenance will be as a normal
garden depending on plant species ensuring that the irrigation
system is maintained and drainage outlets checked.
Important Data
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