CSL West

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Announcements and Updates

TECH TALK: May 2026

 

What is EPS?

Carlisle’s InsulFoam EPS is a rigid insulation board composed of closed-cell, lightweight expanded polystyrene (EPS). This product is available in a wide range board sizes and densities that meet or exceed the requirements of ASTM C578, Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation. InsulFoam Flat offers a long-term, stable R-value and offers excellent dimensional stability, compressive strength, and water resistance.

What are some of the features and benefits?

  • Labor and Cost Savings

    No complicated filler panel systems; can be installed in a single layer for thicknesses up to 40"

  • Environmentally Friendly

    Contains no ozone-depleting blowing agents, may contain recycled material, and is 100% recyclable if removed or replaced

  • Stable R-Value

    Thermal properties will remain stable over the material’s entire service life, no thermal drift

  • Moisture and Mold Resistance

    Does not readily absorb moisture from the environment, does not sustain mold or mildew growth

  • Proven Performance

    Manufactured using the same chemistry since the mid-1950s

  • Variety of Compressive Strengths

    Available in more compressive strengths than comparable insulation products

Where can it be utilized in a Warranted Carlisle Assembly?

  • EPS Flute Fill

    EPS is an excellent option on Metal Retrofit projects over a standing seam metal roof for both mechanically fastened and adhered applications

  • Ballasted Applications

    Flat EPS or R-Tech Fan Fold EPS can both be utilized as a separator board in ballasted applications. These are more cost-effective and will help increase productivity

  • Mechanically Fastened Applications

    R-Tech Fan Fold can be utilized in Mechanically Fastened Assemblies for all membrane types.

EPS Taper

EPS Taper can be either mechanically attached or adhered with Flex Fast Adhesive in warranted assemblies beneath an accepted coverboard or insulation.

Note: If EPS Taper is adhered with Flex Fast Adhesive, the board density must be 1.25# or greater. Please consult with Carlisle’s Project Review Department when considering a fully adhered application with EPS Taper.

What limitations of EPS Insulation should be considered?

  • Compatible Substrates

    EPS is not compatible with Asphaltic materials, PVC Membrane, or solvents (i.e. Bonding Adhesive). Although it can be utilized with Flex Fast Adhesive due to Flex Fast being solvent free, it should never come in direct contact with any of the materials mentioned above.

  • If mechanically fastening TPO over EPS, the minimum density must be 1.25#

  • Contact Project review for density requirements for wind speeds over 90-MPH.

  • 1.25# density is required for adhered systems.

  • R-Value

    EPS Taper does not have the same R-Value as Insulbase Polyiso. While Insulbase Polyiso has an R-Value of 5.7 per Square Inch, EPS Taper’s R-Value varies based on the density.

    • 1# Density = 3.85 R-Value

    • 1.25# Density = 3.92 R-Value

    • 1.5# Density = 4.17 R-Value

    • 2# Density = 4.50 R-Value

    • 2.5# Density = 4.50 R-Value

    • 3# Density = 4.60 R-Value

EPS Assemblies with EPDM Membrane

Due to the surface temperature that can be reached on certain un-ballasted black membrane installations, the following chart should be followed when using InsulFoam products with black membranes:

Considering using EPS on your next project assembly? Please contact Dane Helnore at CSL West or Carlisle’s Project Review Department for technical assistance and support.

 
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