p>GPS insulation is Graphite polystyrene insulation, and it does offer a bit higher R value. We don't have a page specifically on GPS foam but you can use it anywhere you would use EPS rigid foam insulation. EPS is typically rated at abou R4 per inch where GPS is typically rated as having R5 insulating value.</p> <p>Here is our page about<a href="/guides/2372/choosing-the-right-insulation-the-pros-cons-and-applications/" target="_blank"> choosing the best rigid foam insulation</a> where we talk about the charateristics and best applications of different foam products. </p