For a dry mold free finished basement floor always install a vapor barrier before laying a wood subfloor or carpet pad.
Vapor barrier carpet.
Quietwalk sound absorption and vapor barrier 360 sq ft premium 3 mm flooring underlayment.
With a vapor barrier everything below the vb will accumulate moisture until it matches what is in the soil and that is undetermined.
Trafficmaster 6 7 16 in.
For pricing and availability.
Quietwalk sound absorption and vapor barrier 100 sq ft premium 3 mm flooring underlayment.
Installing a moisture barrier underneath your carpet is a always a good idea.
A moisture barrier is installed right beneath your carpet so that if any liquid is spille d it will not seep through ti the floor base.
It will not only help you keep your carpet clean and dry but it will also protect the wood or cement underneath the carpet from becoming damaged.
I would recommend raven industries vaporblock 20 plus or the vaporblock plus 6 as two of the better ones since they also block out radon methane and voc s.
If you have grass the soil is moist.
Density rebond carpet pad with moisture barrier 11 model 150553446 33.
Moisture barrier padding is floor padding that has layer that prevents liquids spills urine etc from passing from the floor to the floorboards and it also prevents vapor from coming up from the base floor concrete etc through the carpet.
However i have found that in most situations homeowners are mislead into assuming that a moisture barrier pad can do more than they are actually designed to do.
Any kind of persistent moisture will allow mold to get a foothold and soon ruin carpet or wood flooring.
Moisture barrier padding is more costly than a standard rebond type of carpet padding.
See what goes into waterproofing a basement too.
The hope of this type of padding is to make moisture less of a headache.