I have a basement with a dirt floor and a field stone foundation. The basement his humid and smells extremely musty which permeates through the floor to the living room. I have tried laying down plastic and running a dehumidifying but I feel I am only dehumidifying the earth since I can't get a seal where the wall meets the floor. I was wondering what my options are?

Someone mentioned to pour a rat slab, about 2" thick. I have plenty of head space so I can afford to lose a couple of inches. Then run a dehumidifier. But will I still have moisture issues due to the field stone?

Can I just spray foam the basement ceiling? Essentially sealing the smell off from the rest of the house?

Should I do both?

Any help would be appreciated.

Paul