Specialist Green Roof Range
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Drain, store and filter water in one layer
UGR 20mm Storage & Drainage Membrane is an all-in-one water-management layer for extensive and intensive green roofs.
Manufactured from recycled high-density polyethylene, its 20mm-deep studded cavities temporarily store rainwater to support healthy vegetation. Perforations within the membrane allow excess water to drain into the space below, helping prevent the growing medium and plant roots from becoming saturated.
A high-quality geotextile filter layer is permanently bonded to the upper face. This prevents soil fines and growing medium from blocking the drainage cavities while also removing the need to install a separate loose filter fabric.
Why water management matters
A successful green roof needs to retain useful moisture while allowing excess rainfall to drain away safely.
UGR 20mm Storage & Drainage Membrane performs three important functions:
- Water storage: Holds approximately 6 litres of water per square metre for use by the vegetation
- Drainage: Allows excess water to pass through the perforated membrane
- Filtration: Prevents soil and fine particles from obstructing the drainage cavities
The bonded geotextile also helps prevent the filter layer from slipping or compressing into the storage cups during installation.
Suitable green roof applications
UGR 20mm Storage & Drainage Membrane can be specified for:
- Extensive green roofs with low-growing vegetation
- Semi-intensive green roof systems
- Intensive green roofs with deeper growing substrates
- Flat roofs and low-pitched roofs
- Houses and residential extensions
- Garages, sheds and garden buildings
- Larger commercial green roofs
- Soft landscaping over decks
- Inverted warm roof applications
- Suitable walkable or drivable landscaping build-ups
Its combination of drainage, storage and filtration makes it a versatile option for a broad range of domestic and professional green roof projects.
For walkable or drivable finishes, the bonded geotextile must be removed, the studs must be filled and the appropriate bedding or sub-base courses installed as part of the specified system.
Strong, durable and long-lasting
UGR 20mm Storage & Drainage Membrane has an approximate compressive strength of 150kN/m², helping it withstand the loads applied by the green roof build-up above.
The recycled HDPE membrane is:
- Tough and durable
- Resistant to water
- Resistant to alkalis and saline solutions
- Resistant to organic acids
- Unaffected by minerals
- Resistant to bacteria, fungi and other small organisms
- Suitable for temperatures between -30°C and +80°C
- Guaranteed against deterioration for 30 years
The product is also tested and CE marked to the relevant standard.
Where UGR 20mm Membrane fits in the system
A typical green roof build-up may include:
- Structural roof deck
- Primary waterproofing layer
- Root barrier
- Protection fleece
- UGR 20mm Storage & Drainage Membrane
- Bonded geotextile filter layer
- Green roof substrate
- Vegetation
Where a dedicated root-protection layer is required, install the UGR Green Roof Root Barrier beneath the drainage membrane.
A protection fleece may also be specified to reduce the risk of light mechanical damage to the waterproofing and root barrier. Consider using UGR Green Roof Protection Fleece 300.
Installing UGR 20mm Membrane
The application surface should have a gradient of at least 2%. Complete the horizontal waterproofing and install any other specified underlying layers before laying the membrane.
- Roll out UGR 20mm Storage & Drainage Membrane over the prepared surface with the bonded geotextile facing upwards.
- Cut the dimpled sheet to the required length, taking care not to damage the waterproofing or any underlying layers.
- Overlap adjoining rolls by approximately 100mm.
- Lift the loose geotextile overlap and position it over the adjoining section.
- Where the joint needs additional protection, seal it using an appropriate compatible jointing tape or sealant.
- Once installed, the membrane can immediately receive the specified extensive or intensive green roof substrate.
The membrane is supplied in a manageable 20m² roll and is installed by simply unrolling and cutting it to fit the roof layout.
Important suitability note
UGR 20mm Storage & Drainage Membrane is not a primary waterproofing membrane or a substitute for dedicated root protection. Where roots could affect the waterproofing or roof structure, install the UGR Green Roof Root Barrier beneath it.
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