Filter cloth, like any filter, is designed to filter. Over time, filters may plug up—think of your car’s air and oil filters, your furnace filter, coffee filter, etc. If green roof filter plugs up, then what?
Because of the aggregate nature of engineered soil, very little escapes through the LiveRoof module’s drain holes. It’s like trying to push marbles through a funnel or a square peg through a round hold. In addition to this simple act of geometry, the roots of the plants bind the soil together and hold it in place.