Moisture barrier

hi i recently bought a house with a tarmac floor the room should have floating timber floor with vents but some dope decided to install tarmac "the smell is awfull i have removed the floor and am down to dirt i was going to install a concrete floor then build walls on it and then timbers on the walls .

my question is should i use a moisture barrier under the concrete slab i vapour barrier concidering it is between the walls and the moisture would have nowhere to go or should i just pour concrete and let the moisture come through concrete and then get carried away by air vents under timber floor thanks.