With so much bickering about where to place plastic sheeting, above or below the xps/eps foam below concrete....why not both? I'm thinking of saving a buck, buying eps and encapsulating it in plastic. Any thoughts?
I think it depends on what your plans are. Are your soils moist and do you envision installing an adhered floor covering such as epoxy? If so, you should be looking at an actual vapor barrier such as Stego. Doubling up the layers of a product like that will add significant cost. If you are just looking to limit moisture intrusion in general then add as many layers of poly above and below the insulation as you'd like. The cost is minimal and there's no real downside.
