UGR 25mm Storage & Drainage Membrane

High-capacity water management for green roofs

UGR 25mm Storage & Drainage Membrane combines water storage, drainage and filtration within one practical layer.

Manufactured from recycled high-density polyethylene, the membrane has 25mm-deep cavities that store approximately 11 litres of rainwater per square metre. This retained moisture helps support healthy green roof vegetation between periods of rainfall.

The membrane is also perforated, allowing excess water to drain into the space beneath rather than saturating the growing medium and plant roots.

Integrated geotextile filter layer

Each roll has a high-quality polypropylene geotextile permanently bonded to its upper surface. This layer:

• Prevents soil fines and growing medium from obstructing the cavities
• Helps stop the geotextile slipping during installation
• Prevents the fabric compressing into the storage cups
• Removes the need to install a separate loose filter layer
• Saves time when constructing the roof build-up

UGR 25mm Storage & Drainage Membrane therefore performs three essential functions within one product:

• Storage: retains approximately 11l/m² of water
• Drainage: allows excess water to pass through the perforations
• Filtration: protects the drainage cavities against soil obstruction

The 25mm cavity provides greater water-storage capacity than the UGR 20mm Storage & Drainage Membrane, while retaining the same approximate compressive strength of 150kN/m².

Suitable applications

UGR 25mm Storage & Drainage Membrane can be used within:

• Extensive green roof systems
• Intensive green roof systems
• Flat roofs
• Pitched roofs
• Inverted warm roof applications
• Domestic roofs and extensions
• Garages, sheds and garden buildings
• Commercial green roofs
• Other suitable walkable landscaping surfaces

For walkable or drivable finishes, the bonded geotextile must be removed, the studs must be filled and the appropriate bedding or sub-base layers must be installed as part of the specified system.

Available sizes

Choose from two roll widths:

• 1m x 10m: covers 10m²
• 2m x 10m: covers 20m²

Both versions include an additional 100mm geotextile overlap along the roll width. The 1m-wide roll may be easier to handle and position on smaller roofs or where site access is restricted. The 2m-wide version covers a larger area with fewer adjoining sections.

Durable and long-lasting

UGR 25mm Storage & Drainage Membrane is an inert, chemically resistant membrane designed for long-term use within the green roof build-up. It is:

• Manufactured from recycled HDPE
• Resistant to water and alkalis
• Resistant to saline solutions and organic acids
• Unaffected by minerals
• Resistant to bacteria, fungi and other small organisms
• Suitable for temperatures from -30°C to +80°C
• Guaranteed against deterioration for 30 years
• Tested and CE marked to the relevant standard

Its life expectancy is stated as equal to the design life of the structure under DIN 9001:2000.

Where UGR 25mm Membrane fits in the system

A typical green roof build-up may include:

1. Structural roof deck
2. Primary waterproofing layer
3. Root barrier, where required
4. Protection fleece, where required
5. UGR 25mm Storage & Drainage Membrane
6. Bonded geotextile filter layer
7. Green roof substrate
8. Vegetation

For dedicated root protection, install the UGR Green Roof Root Barrier beneath the drainage membrane. Where additional protection against light mechanical damage is required, use the UGR Green Roof Protection Fleece 300.

Installing UGR 25mm Membrane

The application surface should have a gradient of at least 2%. Complete the primary waterproofing and install any specified root barrier or protection fleece before laying UGR 25mm Storage & Drainage Membrane.

1. Roll the membrane out over the prepared surface with the bonded geotextile facing upwards.
2. Cut it to the required length, taking care not to damage the waterproofing or other underlying layers.
3. Overlap each adjoining roll by approximately 100mm.
4. Lift the geotextile overlap and lay it over the next section of membrane.
5. Where additional joint protection is required, seal the connection with a compatible jointing tape or sealant.
6. At vertical edges, raise the drainage membrane by at least 150mm or to the upper edge of the finished substrate layer.
7. Once installed, the membrane can immediately receive the specified extensive or intensive green roof substrate.

For smaller projects or restricted working areas, the 1m-wide version may be easier for one person to position.

Storage and handling

Store rolls upright in dry conditions between 5°C and 25°C. Do not expose the product to freezing conditions or direct sunlight, and protect it from UV before installation.

Important suitability note

UGR 25mm Storage & Drainage Membrane is a drainage and water-storage layer, not a primary waterproofing membrane. It must be installed above a suitable waterproofing system and, where required, the UGR Green Roof Root Barrier.