Versatile solutions

As can be seen from the examples above, depending on the needs of the building environ, PMRAs can be engineered to drain water quickly, or retain water and gradually release. A PMRA can also be designed with a conventional drainage system at the roof covering level, as in the case of the aggregate topped federal building.

Another seldomly recognized benefit of PMRAs is reduced landfill. The average lifespan of a PMRA is 25 to 50 years, and the XPS insulation from such roofs can be and often is reused when the building is recovered at the end of the roof life cycle. Roof replacements send billions of cubic yards of waste to landfills annually. Over the lifespan of the building, PMRA roofs are better for the building owner and better for the environment.

PMRAs provide a platform for a variety of commercial and urban residential roof assemblies, including reflective and photovoltaic roofs for energy efficiency, extended roof life cycles, and vegetative roof assemblies for healthy cities. PMRAs support solutions to stormwater detention, mitigating flooding in urban areas, and contributing to water conservation. Finally, they also allow valuable outdoor areas to be repurposed as occupiable spaces.

John Woestman is director of codes and standards to the Extruded Polystyrene Foam Association (XPSA). He has more than 30 years experience in the construction and building products industry with various responsibilities in construction, manufacturing, human resources, marketing, and codes, standards, and regulations. He has a diploma in building trades, a degree in mechanical engineering, and an MBA.