Filter Fabric & Drainage
Beneath the growing media and above the drainage system, the filter fabric keeps the media from clogging up the drainage while allowing water to flow freely. Green Roof Solutions has a 3.5-oz filter fabric, FF35. An important consideration with filter fabric is the flow rate while preventing media runoff. The GRS FF35 has a high flow rate of 150 gallons per minute per square foot. The FF35 is a needle-punched fabric composed of virgin polypropylene staple fibers that are randomly arranged and needle-punched to form a cohesive geotextile. GRS filter fabric is resistant to UV degradation and to biological and chemical environments found in soil.