Icopal Drainage Board 20 FF meets the need for free drainage within any green roof

Icopal Drainage Board 20 FF

The need for free drainage within any green roof is vital to prevent the system from becoming waterlogged and to reduce excess loadings on a roof deck.
Icopal Drainage Board 20 FF creates a 20 mm free-draining void to allow excess water to move swiftly and unhindered to the relevant roof drainage outlet.


Icopal Drainage Board 20 FF is a black, high density polyethylene (HDPE) cuspated drainage board. The board is manufactured from 60 % recycled HDPE. The drainage board has ribbed cups provide additional resistant to compression.

The top surface of the drainage board is perforated to allow excess water to pass through and drain away. A non-woven polypropylene filter fleece is bonded to the upper surface to speed up installation, and is used to prevent the green roof substrate from blocking the drainage voids in the drainage board. The edge of the geotextile extends beyond the core by 100 mm along one edge to allow the creation of overlaps in the filtration layer.


Product Code Description Size
3101081 Icopal Drainage Board 20 FF 0.97m x 50m


Board Size: 0.97m x 50m
Board Depth: 20mm
Geotextile Overlap Width: 100mm
Board Weight/Unit Area (dry): 1 kg·m-2
Board Weight/Unit Area (dry): 8 kg·m-2
Water Storage Capacity: 7 L·m-2
Compressive Strength: 115 kPa

Water Flow Rates: The Icopal Drainage Board 20 FF is has the following flow rates tested in accordance with EN ISO 12958.

           Gradient Water Flow Rate
  1 % Fall = 0. 86 L/m-s
  2 % Fall = 1.20 L/m-s
  3 % Fall = 1.50 L/m-s
  Lateral = 10.0 L/m-s



Icopal Drainage Board 20 FF has been tested in accordance with EN 13252: Geotextiles and geotextile-related products. Characteristics required for use in drainage systems.

Intended Use

Icopal Drainage Board 20 FF is intended for use as a drainage, water retention and filtration layer within both extensive and intensive green roof systems.

Surface Preparation

It is advisable that Icopal Drainage Board 20 FF is laid on the Icopal Protection Layer when being used underneath a planting or hard landscaping scheme. This will reduce the point loading on the waterproof membrane beneath.


Icopal Drainage Board 20 FF is for use in conjunction with the relevant specified components of the associated Icopal Green Roof System. The roof deck and any associated planters should have sufficient drainage points to quickly drain away surface water from the roof.

It is important that additional filter fleece is used in conjunction with Icopal Drainage Board 20 FF around upstands and perimeters to reduce the incidence of fines getting into the system and creating blockages.

Icopal Drainage Board 20 FF can be used in soft or hard landscaping applications.

Installation Procedure

Handle with care to avoid any damage.

Each panel of Icopal Drainage Board 20 FF should be butt jointed, with the 100 mm geotextile flap overlapping onto the adjacent panel. Icopal Drainage Board 20 FF can easily be cut around any protrusions in the roof deck (protection board should be placed under the Icopal Drainage Board 20 FF to prevent cutting of the waterproof membrane below).

The Icopal Drainage Board 20 FF must always be overlaid with the Icopal Filter Fleece at all details such as upstands, kerbs and edges to prevent fines getting into the drainage system and causing blockages.

Typical Specification

Drainage and filtration layer to be Icopal Drainage Board 20FF. Icopal Drainage Board 20 FF is to be laid in accordance with Icopal’s instructions.

Delivery and Storage

Icopal Drainage Board 20 FF is delivered on pallets with two rolls per pallet.

The product should be stored on a clean, flat surface and protected from mechanical damage. 

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