VF SD 40 Void Former

Moulded HDPE attenuation crate used in blue roof system to create a 40mm water retention and drainage layer.

They allow free movement of water across the roof towards the restricted outlets.

They are installed directly over the waterproofing layer (usually with a protection fleece)

They are often paired with 40mm+ flow restrictors to control the release rate of stormwater, often designed to discharge over a 24-hour period.