I am detailing an unvented 600 sq. ft. crawlspace that is 4′ high. The exterior side of the concrete wall is insulated with 5″ of EPS and has been damp-proofed.

My plan now is to insulate the floor with 3″ EPS and cover with two layers of poly that will be mechanically fastened with horizontal battens and acoustic sealant to the side of the footing. to boost the R-value in the wall i will add 1.5″ XPS and then build a stud wall to cover with gypsum wallboard.

My plan is to notch the XPS around the floor joists so that the xps comes into contact with the underside of the floor sheathing above. i would then do the same with the GWB. How does this detail sound?

Also, do i have the HRV supply/exhaust the crawl space? also, i put a section of 4″ PVC pipe through the footing and tied it into the perforated footing drain. this perimeter drain eventually connects to solid pipe and drains to daylight. the idea was it would drain out any water trapped under the ‘slab.’ the plumber thinks i should close this off. should i?

thanks again, gba..