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PMR: A Breakthrough Idea
How a Breakthrough Idea Revolutionized The Roofing Industry
More than 30 years ago, some roofing experts from The Dow Chemical Company took a completely new look at the ways roofs are designed. Quite literally, they turned the industry upside down. In a protected membrane roof assembly, the insulation is placed on top of the membrane, improving the performance and longevity of the roof system. The insulation in a PMR assembly must be able to withstand wet environments (without sacrificing insulation performance) and foot traffic. That's why durable, moisture resistant STYROFOAM™ extruded polystyrene insulation is the ideal choice for PMR.
| Advantages of a PMR Assembly |
- The membrane is maintained at a nearly constant temperature — close to the temperature of the building's interior. This reduces the harmful effects of freeze-thaw cycling and excessive heat.
- The membrane is protected from weathering, foot traffic and other physical abuse, during and after construction.
- The roof is waterproofed first and insulated second — which allows for year-round construction.
- Removal and re-installation of the ballast (for repairs or to construct additional stories) and insulation is easy. And insulation can be reused.
- Many ballast options — such as stone, precast paving slabs, green roof, interlocking stone or concrete — can be used in conjunction with a PMR. And PMR assemblies are compatible with a range of membrane types.
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A PMR roof assembly also helps building owners meet the goal of sustainable construction — including contributing to the achievement of LEED™ (1) points.
| Sustainability Objective |
PMR Benefit |
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Reduce the total energy consumption of the building (life-cycle costing)
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PMR performs year after year — and the more a roof can be kept in use, the more it contributes to the overall sustainability of the building by delaying the impact of eventual tear-off.
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Reduce global warming impact from excessively using energy sources (reduce)
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A PMR using a rigid, extruded polystyrene insulation, with one of the highest R-values per inch, will realize reductions in utility bills, year after year. By reducing HVAC loads, this will lower pollution emissions from burning fossil fuels.
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Reduce the downstream waste during construction, maintenance and demolition phases (reuse, recycle)
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Because the insulation, fabric and ballast are loose-laid in a PMR, many times these components can be reused after maintenance or major construction.
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Offer recycled content and/or environmentally friendly reusable products (recycle)
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Dow incorporates recycled materials into its finished goods. For example, Dow has been internally recycling trimmings from the production of STYROFOAM extruded polystyrene for more than four decades. Scrap, such as cuttings from board edge treatments, is recycled back into finished products, reducing waste and storage and landfill costs.
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(1)The U.S. Green Building Council, a nonprofit coalition promoting high-performance green building design, has developed Leadership in Energy and Environment Design (LEED), a voluntary, consensus-based standard. The LEED rating recognizes the life-cycle costing of construction.
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Learn more about PMR by visiting:
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