I am currently investigating options for adding some type of subfloor to my basement to try to make the floor feel warmer when finished. The types of flooring being looked at is carpet, engineered wood, and tile.

The house was built in 2004 and I do not remember any foam being placed under the slab before it was built. I do remember pea gravel.

I did the plastic sheet taped to the floor and did not notice any condensation.

The house uses geothermal heat. The basement does have cold air returns and duct vents.

To try to save ceiling height I am considering something like DMX airflow with 5/8 advantech on top. DMX’s website says the airflow product has an r3 rating. For peace of mind would it be better to include 1/2” or 3/4” rigid foam board between the DMX and the advantech?