I have mold issues (CIRS) and need to be careful how much mold and what types of mold are in my home.  Many homes I am looking into purchasing have slabs and it is somewhat doubtful that there is any moisture/vapor barrier under them.  Will retrofitting a floor with a 6mm vapor barrier do the trick, or will the sills which contact the slab carry the moisture up into the walls?

Thank you!!!
Steve