Henry Filter Fabrics are an integral part of green roofing assemblies, providing resistance to most soil chemicals, acids and alkali. Henry Filter Fabric is a non-woven geotextile made up of non-biodegradable polypropylene fibers. These fibers are needled to form a stable and durable network that retains their relative position. It’s exceptional tear resistance and high permeability prevent the passage of soil, ballast, and other loose material into the waterproofing assembly below the fabric.