The Root Barrier is a non-reinforced, heat-weldable, polypropylene sheet specifically formulated for use in below-grade and vegetated applications to resist root penetration and soil bacteria. It is typically used in medium to deep Roof Garden assemblies where plants, such as grasses, with intrusive roots are used. This high-performance Root Barrier is based on a UV-stabilized polypropylene copolymer which does not require polymeric or liquid plasticizers to maintain flexibility. The relatively smooth surface of the Carlisle Root Barrier facilitates production of a total surface fusion weld that creates a watertight, consistent, monolithic sheet.