I am in the planning stages for a new house and have a question concerning insulating under the basement floor. I live in eastern canada and the house will be 1740 sq ft with a walkout basement in the rear. I understand that XPS panels will make a significantly warmer basement floor however I have also heard that window cutout panels from foam core doors work better than XPS panels and are usually cheaper although I have been unable to find any information on exactly how to install these panels. For XPS I know you lay them on the gravel and tape the seams however with the window cut out panels I would think there would be far too many seams to tape them all. Would anyone hear have any insight into the foam core window cutout method of insulating under a basement floor?

Thanks,

Darrell

It makes no sense. Foam is foam, and the R-value from one foam to another doesn't vary enough to matter. Your architect should be able to advise you on the best insulation methods for your climate.