“White membranes, throughout the northern part of the U.S., may be a tool by which heat island concerns could be addressed, but they do not deliver energy savings, nor do they contribute to lower carbon emissions,” stated Carlisle Syn-Tec’s Director of Design Services Samir Ibrahim. “The key factor should always be the amount of insulation utilized in the assembly, which has been demonstrated as the most influential component by which sustainability can be achieved.”

Faced with the challenge of engineering a cost effective, sustainable, energy efficient roof system, that is designed to eliminate potential roof failures, and maximize our client’s ROI; we knew the components needed to coalesce. Insulation is a primary component that supports the energy efficiency of a roof system.

A quick compare and contrast will better clarify why we prefer Expanded Polystyrene (EPS) as our leader of insulators.

Proper Insulation Is The Key To Energy Savings:

This insulator’s R-value performance can vary depending on many things: density, type of blowing agent, how it’s handled, how it absorbs moisture, and conditions under which it was installed. Due to thermal drift (the loss of R-value), Polyisocyanurate’s insulating value may decrease to an R 5.6 within 180 days of manufacture.

Other issues to consider :

Less Durable

  • Will easily take on moisture and condensation
  • Easily crushed by roof-top traffic, destroying the bond between the foam and facer
  • Dimensionally unstable 2)

Diminishing R-Value

  • The Research Council of Canada found that the R-value of permeable-faced Polyiso insulation degrades 20% over five years.
  • Research from the Oak Ridge National Laboratory set R-value deterioration for permeable-faced polyiso at 15%.
  • A Dynatech Research and Development Corporation study shows the aging rate of most impermeable-faced foams was only 10 to 20% slower than un-faced foams.

Expanded Poly Styrene (EPS) – Dura-Ply’s preferred insulation

EPS is a closed cell insulation blown with an air molecule that has NO THERMAL DRIFT. Will not take on any type of moisture, and can withstand the pressures from roof traffic.

Other Benefits include:

  • Cost effective – More R-value to the dollar
  • Unaffected by moisture – Even when wet from roof leaks, dew-point collection, or interior moisture collection, the R-value is unaffected
  • Withstands the rigors of temperature cycling, assuring long-term performance
  • Will not decompose & will not support mode or mildew growth
  • Cell memory, will not crush
  • Dimensionally stable
  • FM approved

Comparing R-Values of Insulations

InsulationR-Value todayR-Value
after 6 mo
after 5 yr