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Wallbarn Protecto-Drain 20P Perforated Drainage Membrane - 20m x 2m

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Protecto-drain 20P was developed for use as a reservoir and drainage layer in green roof construction. It is placed on top of the waterproofed, protected concrete deck and sits beneath a filter layer, the soil substrate and vegetation layers on extensive green roof systems.

The HDPE membrane is manufactured with the same 20mm cups, but the area between the cups is perforated. On a horizontal plane, this allows water to fillup in the cups  helping to sustain the roots with any excess water escaping through the holes and able to run away beneath the membrane into the drainage outlet. This is a simple but effective way of holding a modest amount of water beneath the root systems but preventing the area becoming waterlogged, which will kill the plants. Because of the egg-box shape of the membrane, a constant air gap beneath the HDPE is maintained, allowing the excess water to pass easily without clogging.

The water held in the cups can then be drawn back up through the filter layer to nourish the vegetation above. This means that a constant level of water can be held in the reservoir cups, but rainwater is efficiently removed effectively and quickly from the roof, which will not become overloaded (never underestimate the weight of standing water). It is important to remember, however, that these materials alone do not provide a drought resistant system. Regular watering and maintenance is required for all roof
gardens and green roofs.

Wallbarn Protecto-drain 20P is lightweight and easy to transport and install, making it ideal for rooftop applications. It is the perfect product for either large-scale roofs or small domestic projects. Large amounts of membrane can be installed in a day, as operatives can simply roll it out across the deck and overlap the edges quickly and easily. By installing the soil substrate immediately, the membrane is properly ballasted. Protectodrain 20P is suitable for EXTENSIVE green roofs. This includes sedum roofs, wildflower and biodiverse roofs, grasses and dwarf plants, where soil substrates are up to a depth of 200mm.

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