Planks!

Foil underlayment is typically used over concrete floors.
It has a reflective quality that acts as a moisture barrier and slightly
increases the insulation value. Very rarely do our installers request
it…..they just use the regular “silencer” underlayment we stock. For
“click together” Moduleo, the manufacturer recommends a product called
Xtrafloor underlayment for subfloors that are not perfectly smooth. Some
installers will use an underlayment, but many will just install the click-together
Moduleo over existing floors.

Hope that helps!