Below Grade



Below Grade Rigid Applications
For exceptional, long-lasting performance in below grade applications, no EPS or XPS competitive product digs deeper than ThermalStar® X-Grade.® With its outstanding thermal and physical properties, durable ThermalStar X-Grade protects foundation walls during backfilling, while providing excellent insulating performance. Patent pending integrated termite resistance assures peace of mind.


Long-Lasting Thermal Performance

ThermalStar X-Grade has been proven to absorb minimal moisture. Also, unlike other insulation products, ThermalStar X-Grade is a “breathable” material. This breathability ensures long-term performance. In fact, a 15-year comparative study of actual field applications of below grade insulation confirms the R-value is retained.

Integrated Termite Resistance

Termites can do serious damage to untreated building materials. With ThermalStar X-Grade, a proven termiticide is integrated into the chemistry of the product and is not a surface coating. US building code requires that rigid foam demonstrate resistance against termite attack when used below grade. In many states, X-Grade is approved for this use — see ICC-ES Evaluation Report (.pdf).




pdficon_small ThermalStar X-Grade Product Information Sheet

pdficon_small ThermalStar X-Grade Rigid Polystyrene R-10 Comparison Sheet

pdficon_small ThermalStar X-Grade Substitution Request Packet

pdficon_small ThermalStar X-Grade GX Substitution Request Packet

pdficon_small ThermalStar X-Grade Canadian Product Information Sheet

pdficon_small ThermalStar X-Grade Canadian Rigid Polystyrene R-10 Comparison Sheet

pdficon_small Technical Bulletin 104: Drying Potential

pdficon_small Technical Bulletin 105: Water Absorption & R-value Retention