Increase radiant system performance and comfort with a reflective underlayer that directs heat where you want it, up into the room. This 48 in. x 125 ft. roll covers 500 sq. ft. and serves double duty as a radiant barrier and vapor retarder. Provides 95% reflectivity (ASTM C1371). The foil meets ASTM E84 and E2599 fire standards and resists fungal growth (ASTM C1338). Use beneath Grid Module and Aluminum Heat Plate hydronic heat assemblies or between joists in staple-up systems to help reduce downward losses and support lower supply water temperatures creating an ultra-high efficiency system.Installation is straightforward: unroll, cut to length, and fasten with staples; seal seams to maintain a continuous barrier. In joist bays, maintain an air space adjacent to the foil for optimal radiant performance; add insulation below as required by local code. Above basements, crawl spaces, or garages, the barrier helps separate conditioned space from cooler zones. The material trims neatly around obstacles and is low dust compared with many fibrous products.Engineered for hydronic radiant floors, the foil also pairs well with electric underfloor heating. Combine with Grid Modules PEX and Aluminum Heat Plates to spread heat evenly and our pre-assembled distribution/control panel for quick, professional commissioning. Durable, tear-resistant foil stands up to handling during layout.