Flintglas® Ply 4 is a functional building block within CertainTeed's built-up roof systems. Built-up roofing or BUR derives its unparalleled strength by building up layers of ply sheets and hot asphalt. Ply sheets are set in hot asphalt and layered, ply/asphalt/ply/asphalt. The asphalt flows through the plies and coats them, curing to an incredibly robust, watertight roof system. This 24 mil sheet is manufactured with an extra strength fiberglass reinforcement, offering exceptional dimensional stability. The top, weathering layer of a Flintglas® Ply 4 built-up roof system can be a surfacing of flood coat and gravel or Flintglas MS Cap Sheet. Face it - some old dogs don’t need new tricks, and CertainTeed hot asphalt low-slope roof systems have consistently delivered on the promise of protection for generations. These systems offer multiple watertight layers with unparalleled bond strength. So when the risk of a roof leak means more than just a maintenance nuisance, trust wha...See Moret works and spend the time to install peace-of-mind. Reach out to your local CertainTeed Territory Manager to request a sample and demonstration of Flintglas® Ply 4. See Less