How to Soundproof an Existing Wall: 15 Ways, Without Removing ... May 22, 2022 · Or you can cover your existing wall with MLV (glued, or nailed), Then add one layer of 5/8″ drywall. Leave 1/4″ gap between new drywall and adjacent walls, ceiling, and floor to decouple the wall. Fill the gap wit Green Glue sealant. Finish your drywall with tape, mud, paint. Don’t forget plug extenders for the electrical boxes.