Home > Companies > Alumasc Building Products Ltd > Floradrain® FD25

Floradrain® FD25 is a lightweight drainage and water storage board, manufactured from thermoformed recycled polyethylene, used mostly in extensive green roof applications. The product allows aeration of the substrate; evaporation of stored water and multidirectional drainage on the underside. Hard landscaping elements can also be built directly off the board.


  • FD25-E: 2 x 1 m panel.
  • FD25-R: 15 x 1 m roll.
  • FD25-RV: 15 x 1 m roll with integral filter sheet (SF).


Install by loose laying directly onto the root resistant membrane (overlaid with a moisture resistant mat where specified). The 2 mm diameter aeration holes must be uppermost (except when installing under hard landscapes, when the boards can be laid upside down, to allow quicker drainage). Butt joint the boards and connect with plastic clips (two per square metre). Panels can be cut with a heavy duty knife or a small toothed saw to fit around protrusions. Overlay with an appropriate filter sheet and substrate.

Standard product features




25 mm.

Dry weight:

1.7 kg/m².

Wet weight:

4.7 kg/m².

Water storage capacity:

3 litres/m².

Filling volume:

10 litres/m².

Compressive strength:

>270 kN/m².

Waterflow rate:

  • At 1:60 fall: 0.5 litres/second/m².
  • At 1:33 fall: 0.8 litres/second/m².

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-65-50/354 Plastics or rubber studded sheets

NBS Specification

NBS Buliding logo
This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Alumasc Building Products Ltd


+44 (0)1744 648400

Product reference

[Floradrain® FD25-E]
[Floradrain® FD25-R]
[Floradrain® FD25-RV]

Manufacturer details

White House Works,
Bold Road,
St Helens,
Merseyside, WA9 4JG
Tel +44 (0)1744 648400
Fax +44 (0)1744 648401
NBS Plus