Our ODISI solution for green roofs
A high-impact innovation for green roofs
- How can we ensure the survival of green roofs?
Climate change is having an impact on temperatures, which are getting hotter, and on water resources: alternating periods of heavy rainfall followed by periods of severe drought.
There are major disparities between regions of the world. Cities are strongly impacted by these extreme events, with the creation of increasingly frequent " urban heat islands ".
In 2022, 82% of the French population will live in urban areas: to combat this overheating of city centers, it is necessary to set up " cool islands ". These are based on three pillars: vegetation, water and shade. We have developed innovations that meet these needs. Starting with the observation that roofs account for around 30% of a city's impermeable surfaces, we have developed the ODISI green roof solution.
This combined drainage and irrigation sheet ensures roof drainage and plant watering in a single step. Once laid on the waterproofing layer, the weight of the substrate and plants holds it in place.
Watering compensates for low rainfall and plant consumption to ensure healthy vegetation and environmental cooling through evapotranspiration.
- WHAT IS A GREEN ROOF? HOW CAN IT BE INSTALLED?
When creating or renovating a building, house, apartment block, etc., it is possible to vegetalize the roof by superimposing a drainage layer, substrate and vegetation above the waterproofing layer.
1. Green roof
2. Waterproofing area
3. Waterproofing layer
4. Substrate
5. Vegetation
6. ODISI:
72. Alternating drains
80. Alternating drip irrigation
The framework must be able to support a load of between 80 and 250kg/m², depending on the type of vegetation chosen.
A study is necessary to estimate the maximum weight your structure can support and then adapt the choice of substrate (water weight, thickness...), plants, drainage/irrigation system...
The slope of your green roof can range from 1-2% to 20% for standard cases(French professionnal rules: "Règles Professionnelles pour les Toitures et Terrasses végétalisées").
There are 3 types of green roof:
- Extensive
- Semi-intensive
- Intensive
- What's the benefits of ODISI, enabling drainage and irrigation?
Roof drainage is often mandatory
The drainage layer evacuates excess water to prevent root rot caused by asphyxiation. In France, it is compulsory for slopes of less than 3%, and may be optional for structures of less than 20%. In this case, the maximum water retention of the substrate must be ≥ 35% of volume, or the vertical permeability of the substrate must be ≥ 6 mm/min. For semi-intensive green roofs, drainage is mandatory regardless of the slope percentage. A wide variety of materials can be used for drainage (granulates, porous alveolar elements, geotextiles, etc.). The drains in the ODISI nappe are spaced at 50 cm intervals. Contact us for details of their hydraulic characteristics.
A filtration layer to secure drainage
ODISI's top layer is essential to its operation: it filters the water and separates it from the substrate. Positioned under the substrate, it prevents clogging of the drainage and drip irrigation systems. The filtering layer and drainage are essential to the proper functioning and longevity of green roofs.
Watering is essential for healthy plants
Water is essential for the survival of plants, especially in the constrained, low-substrate environment of green roofs. Plants are made up of over 80% water: sedum, for example, contains 85%. Water intake enables vegetation to provide ecosystem services such as combating urban heat islands: 95% of plant water is evaporated by the leaves. It is this evapotranspiration (ETP) that enables cooling according to light radiation, T°C, hygrometry and wind. A substrate without water means a water-stressed plant, with little or no evapotranspiration and therefore no cooling. On the other hand, we are also aware that water is precious and that its use must be as sparing as possible, while respecting the quantities available.
A watering point is mandatory
Regardless of the type of green roof chosen, watering is required for plant installation: a watering point is mandatory on every green roof or terrace, and must be within 30 m of any point on the roof/terrace. This watering system must be sized according to the surface to be irrigated and the type of substrate and vegetation.
It must last at least until the vegetation takes root in the substrate, particularly in the case of sowing seeds, sedum fragments, planting plugs or cups, installing pre-cultivated mats...
Subsequently, watering the green roof in a controlled manner will ensure its good health and survival in the event of drought. We recommend installing a weather station to optimize watering, taking rainfall into account and evaluating the potential evapotranspiration (ETP) to be corrected by crop requirements (Kc cultural coefficient).
Reasoned watering
Watering, when necessary, balances rainfall inputs and evapotranspiration losses to:
- Improved plant recovery during planting
- Ensuring the long-term resilience of the vegetation in place
- Less maintenance work in terms of weeding, reseeding, etc.
ODISI: an underground drip irrigation system for greater efficiency
A drip irrigation system positioned every 50cm ensures watering when required, with a dripper every 30cm and a flow rate of 1l/h. Watering must be sized according to the needs of the plants and the maximum water holding capacity of the vegetation complex. It is advisable to divide the watering up and automate it. ODISI's integrated distribution network ensures that water is distributed evenly between two watering cycles. This network is ideally positioned under the substrate to avoid the water losses of sprinkler irrigation. The water reaches the plant roots without wetting the foliage, thus avoiding fungal diseases.
Positive points:
- Ideally positioned for water efficiency
- Healthy plants
- Cooling thanks to evapotranspiration from plants
A retention and distribution layer for optimum water management
This water retention and distribution layer is ODISI's final layer. Combined with the needle-punched filter sheet that maintains the drip and drain network, it ensures even watering of vegetation.
Its water retention capacity, combined with that of the substrate and the water stored in the plant, helps toreduce the amount of water inflows into the pipes during heavy rainfall. If the ODISI solution is coupled with a water retention system, this multiplies the impact of the solution by storing more water that can be reused after filtration during dry period. This allows to manage the green roof as autonomously as possible. We can also advise you on how to automate the irrigation of your green roof to save time and ensure the longevity of the installation.
- A solution with impact
Article: The environmental and human impact of revegetation
Green roof has many advantages, including:
- Environmental: welcoming biodiversity, water management, reducing urban heat islands
- Economical: longer service life for the waterproofing layer, energy conservation in the building thanks to improved thermal insulation
- Social/public health: aesthetic pleasure, sound insulation, better air quality
Contact us for your project sizing
our latest news
Ecological and Energy Transition Open
"Sharing projects to discover solutions and innovations". We participated in the Open de la Transition Ecologique et Energétique organised by Bretagne Compétitivité with the Brittany Region, the CCI
What type of green roof should I choose for my home?
Extensive or intensive green roof? What are the factors to consider when choosing a green roof?
Végépolys conference "Urban Cool Islands: challenges and innovative solutions"
Climate change and its heat peaks are having an even greater impact on urban areas. Plants are one of the answers to the problem of Urban Heat Islands. But plants have a hard time surviving these hot, dry periods.
- faq: the answer to your most frequently asked questions!
The ODISI roller weight around 33kg. It can be fitted into an elevator to go easily to the roof (2m wide).
On the roof, position directly ODISI on the waterproof roof covering. Then, spread the substrate in an even layer and position the vegetation. The waterproofing for green roofs is resistant to root penetration.
The slope of the roof must be less than 6% for the product to work properly. You can provide a storage area for the water collected during drainage, so that it can be reused during dry periods.
Yes, the size of a roll is: 20m long by 2m wide. ODISI can be cut to fit smaller spaces in width and length.
Two sheets can also be overlapped to cover greater widths or lengths. In this case, be sure to keep the layout consistent: a drain pipe and then a drip irrigation pipe, alternating every 50cm.
You need at least the width of a drip and a drain (every 50cm). So surfaces must be at least 1.20m wide.
There's no limit to the maximum size: it's the collection, water supply and storage network, the pump... that need to be sized according to the surface area of the product installed.
Contact us for any project over 400m² on a roof: we'll be happy to help you size it.
The ODISI sheets are designed for easy overlapping. You can place a second sheet on top of the first. We recommend an overlap of 10-15cm.
The weight of the substrate will hold both sheet in position.
All sources of water can be used. We recommend collecting drainage water during rainy periods and reusing it during dry periods.
Water must be filtered to a minimum of 130 microns to ensure proper operation and durability of the drip irrigation system.
Take care to ensure sufficient water flow for the entire surface.
Remember to winterize the irrigation system to prevent frost damage.
It's essential to ensure that plants get off to a good start, whether sown, planted or rolled out. To achieve this, the substrate, Urbanscape Green Roll or soil / compost mix must be saturated with water. The vegetation must then be watered copiously to ensure good emergence and/or rooting of the plants.
It's best to install during a rainy period, and not too hot. Irrigation should then be carefully monitored to adjust its automation. We advise against installation in summer.
For green roofs, ODISI is suitable for extensive and semi-extensive vegetation.
For gardens, we recommend limiting plants to those with root systems no larger than 10-15cm. The roots must not become embedded in the ODISI layer. When laying rolls of turf, make sure that the rolls are laid edge to edge, but without overlapping, as with sedum rolls.
The precise choice of plants will depend on your climate and location.
Once the ODISI sheet is in place and protected by the substrate, it can be walked on without damaging the drainage and drip irrigation pipes.
