Roof Insulation: A Comparison of Performance & Environmental Considerations

By: Tamara Middleton, Sales Representative – Architectural Products

Most flat commercial roof buildings today use one of three insulations: polyisocyanurate (polyiso), extruded polystyrene (XPS), or expanded polystyrene (EPS).  These are used above the roof deck and protected by the roof membrane.  Polyiso is the most commonly used of the three, this is due to its higher R-Value; however, overtime that R-Value has been decreasing.

Updated 2016 NRCA Polyiso R-Value Recommendation

Updated 2016 NRCA Polyiso R-Value Recommendation.  Learn more.

Polyiso originally used CFC’s for its blowing agent, while that gave the insulation a higher R-Value, it is extremely hazardous to the environment.  In 1993 the polyiso industry shifted to HCFC-141b, causing a significant decrease in their R-value.  In 2002 the industry shifted to HCFC-142b.  However, while HCFC’s are only 5% to 10% as damaging to the ozone as CFC’s, they are still damaging and by 2020 HCFC-142b must also be phased out. XPS currently uses HCFC-134a, this will also be phased out by 2020.  EPS roof insulation on the other hand does not use and CFC’s or HCFC’s for its blowing agents.  EPS is expanded using pentane.  Pentane is a hydrocarbon and does not cause ozone depletion or global warming.  Around the country several EPS manufactures are redesigning plants to recover up to 95% of the pentane used.

All three insulations use flame retardants in order to meet building code standards.  Both EPS and XPS use HBCD which is non carcinogenic but it does have health concerns.  HBCD makes up 2.5% of XPS and 1% of EPS.  Polyiso uses TCPP which makes up 5% of the insulation.  TCPP has been shown to be harmful to aquatic organisms but has limited human toxicity.

Expanded polystyrene, Extruded polystyrene and Polyisocyanurate are all non-biodegradable.  Any one of these in a land fill will be there indefinitely.  While polyiso can be recycled it is a complicated process and there are no programs in place for recycling.  EPS and XPS are also recyclable and several programs exist across the country for the recycling of EPS.  Most EPS manufacturers accept all construction and packaging grade EPS for recycling.

Learn more about EPS recycling opportunities or Foam-Control and Foam-Control PLUS+ expanded polystyrene (EPS) Roof Insulation.

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