News From Go Plymouth Foam

Best Insulation Not Being Specified - Insist On It

Bidding a project and Wondering why XPS 250 (R-10)
is specified for foundation insulation?


XPS (Extruded Polystyrene) and EPS (Expanded Polystyrene) are both closed cell rigid insulation that have the same compressive strength abilities. Many Specifiers and Contractors do not really understand the difference. You should! There is a BIG cost difference.

Many Specifiers and Contractors believe that XPS insulation provides a consistent R-value of R-5/inch in foundation insulation. Not even close. Two reasons: One, XPS uses a blowing agent that provides additional R-value that escapes and over time lowers the R-value. In fact, the federal government has now stepped in and mandated XPS rate their product using the R-value method of
LTTR (Long-Term Thermal Resistance) as of October 2019 (see Full Disclosure Article). According to new research by the EPS-IA, XPS insulation’s 50 year age adjusted (LTTR-50) R-value is estimated to be 4.3 R-/inch. Two, research has shown that XPS placed below grade loses 48% of its R-value. This is due to the cell structure and manufacturing process of XPS. The study concluded that once XPS takes on water it has a hard time breathing it out.

Why Insist on EPS Engineered EPS for Foundation Insulation

Insist on Plymouth Foam Engineered EPS


The technological advancement for Engineered EPS is truly amazing and the new research is showing why you should insist on using Engineered EPS Foundation Insulation on your project. EPS’s R-value stays consistent over the life of the product and we guarantee it! EPS Type IX (250) has a R-Value of 4.35/inch. EPS is a greener product as it does not off-gas a harmful blowing agent and it is 100% recyclable. Want to save money on a project? Ask your specifier to value engineer and use Plymouth Foam Engineered EPS. The saving will surprise you.

Need more help convincing the specifier that Plymouth Foam's Engineered EPS is the best product?
Ask us for our substitution package.