Basement Subfloor - Variant of above
If I may, I have a somewhat different circumstance about which I would like to ask, in particular Dana, if willing to advise.
The background:
Location - northern Ohio ... soil is ~3' of clay, then ~2-3' sandy clay, then sandstone (based on geothermal well data).
River 120' behind house, about 30' below basement floor; floodplains are 1/2 mile downriver. No realistic chance of flood.
French drain + drain tile, courtesy of yours truly, around 2 sides of the house, thinking of extending this to 2 1/2 sides of the house.
Previous owner finished the basement. Outside walls were dug out and waterproofed, Rub-R-Wall was the brand/company/contractor, if memory serves. Backfill material, where I've seen it, seems acceptable, but landscaping overtop was poor, very clay-y "topsoil".
Previous owner then contracted with Big Orange Boxstore to finish the basement. Carpet on pad directly on concrete; walls of untreated 2x4s, standard gypsum board, no greenboard, Drywall ceilings as an added benefit. :-/
Hurricane Sandy happened. Circumferential winds whipped across Lake Erie, the latter devoid of trees, knocking out power for 8 hours, resulting in 2" of water in basement. Contracted to get basement dried out properly, walls treated, etc. Carpet and pad now gone. Sump pump removed, sump crock filled with concrete ... because I had the sump drain excavated out, given that I have the aforementioned drop that allows me to drain my footer by gravity without relying on electricity. Basement floor has been entirely dry since.
Planning on putting in a floor according to the recommendations already well discussed above, on 1" XPS etc. etc. etc.
FINALLY we can get to my question - what, if anything, should I do about the untreated 2x4s and regular gypsum board? Leave it alone? Cut out the lower 4' of gypsum board and replace with greenboard? What about the studs and sill resting on the concrete floor? Leave as is? Cut out the existing studs (one at a time) and replace the lower 4' or so with a "knee wall" built from treated lumber? If I should really replace the wall in some way, then how should I run the 6 mil plastic - up the wall for the 4' distance, or less, or not at all? Should the studs be insulated (and thus set off) from the wall?
Many thanks in advance for your thoughts.