MDP for green roofs

Green roofs buffer rainfall, clean the air, cool their surroundings and regulate indoor temperature. But the drainage layer and filter fabric in a conventional build don't direct or store rainwater well, and the drainage layer's thickness depends on the roof structure and the storage needed.

A simpler build-up

MDP can be laid directly in the soil layer of a green roof to drain, store and recycle water. The separate drainage layer and filter membrane are no longer needed. In principle, a root barrier, soil and MDP are enough to start planting.

Layouts vary with the site and the planting. Pipes can be connected in a cross pattern or a serpentine pattern, and can discharge through several collector outlets or all run to a single outlet.

Using MDP to fill a tank

When MDP feeds a tank or reservoir, the pipes must sit above the stored water level. If the tank's water level rises above the pipes, flow stops. Kept below the soil water and above the tank, filtered water runs into storage naturally.

This approach could give cities a better way to manage and use rainwater, reduce the load on drainage networks, and create more green space.