Fibre Flex - 5LAn easy to use non toxic compound for waterproofing parapets, flat roofs, roof tiles, walls, gutters, water features and fish ponds. Fibre Flex is an ideal compound for repairing old acrylic and membrane systems that have over time begun to leak. Fibre flex has a built in membrane so an additional membrane is generally not required (except for areas susceptible to significant movement). In areas of long term ponding (ponds and water features) or on