Soundproof a floor: Standard (Level 2)

Although this is not truly a decoupled floor system, you'll find this is the next best thing.

Glue down the Serena Mat® to the original subfloor, which could be a slab or wood frame. Then glue down a layer of 3/4" Tongue and Groove OSB. OSB resists warping better than plywood.

Take care if the floor has valleys and crowns, as the plywood may not lay flat. This may require a concrete Tapcon screw to be installed and later removed when the glue dries. You can weight with a bag of sand or a heavy object as well.