Patching and Plastering - Sheetrock mold in basement

A friend of mine just told me that his wife and son have been getting sick lately because of the mold growing in their basement. I said, "I thought you just finished your basement." He replied, "I did, but when I put the sheetrock up on the outside walls I didn't put a plastic sheet behind it. Apparantly if you don't do this mold can seep through the walls." Is this true? Does every finished basement wall need a plastic barrier behind it?

I don't know for sure but in moist climates you always install a vapour barrier over the insulation under the drywall to prevent the heat from pulling moisture through. I would think that most basements would qualify as a moist enviroment.

mold doesn't "seep" through the walls, but as marksr stated, the moisture not being prevented will promote mold and mildew. tell your friend to have his situation inspected and tested. "mildew" or common "mold" is bad for several reasons but is not always a serious health problem, however "black mold" is.