Flexstone is Canada's premier sundeck waterproofing system. The rugged one-of-a-kind membrane is a simple-to-apply common-sense solution for sundecks, flat roofs, garage floors and more. Flexstone is seamless, attractive and CCMC approved for applications over living space. Flexstone Coatings are like no other waterproofing membrane in Canada. Our liquid based urethane formula creates a rugged, flexible, and waterproof surface that has no seams, which means no leaks.