HDPE water drainage board also call plastic drainage sheet is a type of green roofing and foundation driange systems which are
drained by a special molding plastic sheets. Water is retained and drained off within dimple on the upper sides of the drainage
board; excess water spills over the edges of the plates and is carried off from the roof or foundations. The drainage board are made from HDPE(high-density polyethylene), using high pressure to inject plastic to form hole-lump-shaped shell, with stereo space and support level; in the top of the shell, covering with non-woven as filtering level for water percolation, water storage and water drainage.