At K Single Corp we specialize in the installation of Thermoplastic membranes (e.g., PVC, TPO) The most common thermoplastic roof membranes are PVC and TPO. The following provides general descriptions of these two systems Low slope(flat) roofing includes water impermeable, or weatherproof, types of roof membranes installed on slopes less than or equal to 3:12 (14 degrees). There is no one roof system that is best for all applications. Keep in mind that even if you are using the best materials, your roof system still can be installed improperly and you could end up with a leaky roof. Good workmanship and proper attention to detail (e.g., flashing and drainage issues) are just as important as material selection. Also, maintenance plays an important role in roof system integrity and service life.