Where you have a level and moisture-free subfloor, Basic 20 underlay is the optimum choice. It's inexpensive, offers good comfort and support, and has reasonable soundproofing and thermal qualities too. It's particularly useful for upper floors where moisture isn't an issue. Tog rating: 0.72. If you're looking for an underlay that performs well on subfloors with moisture present, have a look at our Aquastop underlay.