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ThermalStar® Below Grade Insulation

With up to 20% of a building's total heat loss occurring at the perimeter and slab of the foundation, below grade insulation is a vital component of a building’s envelope to achieve energy efficiency. ThermalStar Insulation Board is an architectural grade rigid insulation with a variety of R-values and high compressive strengths to support all your high load applications.

With more than 50 years of experience, all of our products are manufactured under an industry-leading quality control program monitored by UL and ICC-ES. ThermalStar Insulation Board provides unmatched quality, with a stable long term R-value that will last the lifetime of your structure.


  • Multiple standard thicknesses, ranging from 1/2" to 4"
  • High load bearing, with compressive strengths as strong as 60 psi
  • Stable, long term R-value
  • Minimal long-term moisture retention with the ability to dry quickly
  • Integrated termite resistance for additional protection
  • Limited lifetime warranty for physical and thermal performance, and termite resistance when applicable
CTA Architectural 580x387
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