Products / Hydrotech Protected Membrane Roof Assembly

Hydrotech's Protected Membrane Roof (PMR) assembly reverses the usual order of a low-slope roof: Monolithic Membrane 6125 is applied directly to the deck, covered with a Hydroflex protection sheet and loose-laid DuPont Styrofoam extruded polystyrene insulation, then held down with ballast so the membrane stays near building temperature and out of sun and traffic. The maker lists stone ballast over a stone filter fabric (a minimum of 10 lb per square foot in the field and 20 lb per square foot at perimeters and large penetrations), ballast pavers, Hydroguard panels, the Ultimate Assembly paver deck and the Garden Roof assembly as topping options, and says no separate vapor retarder is needed because the dew point falls above the membrane. Its cool roof page describes PMR options using white aggregate with an SRI above 78, ballast of at least 17 lb per square foot under the ASHRAE 90.1-2007 addendum, Glacier White concrete pavers with an SRI of 78 or better, or Hydroguard with a reflective coating reaching an SRI of 109. The MM6125 brochure says single-source full assembly warranties can cover membrane integrity, the thermal performance and wind resistance of the insulation, and removal and reinstallation of Hydrotech-supplied topping materials for up to 30 years; the PMR Planning Guide's insulation page adds that thermal resistance will not vary by more than 10% and that wind resistance is warranted up to a 73 mph peak gust speed.