Every few months a client asks us to "soundproof" a wall — usually a primary bedroom next to a kids' room, a home office that shares a wall with a laundry, or a home theater. The honest answer is that no wall gets to true silence without a real budget, but there's a useful hierarchy of what works and what's worth paying for.
The four levers
Acoustic control on a partition wall comes from four things:
- Mass — heavier walls transmit less sound. Two layers of drywall beat one.
- Decoupling — if the two sides of the wall aren't rigidly connected, sound has a harder time jumping across. Staggered-stud framing, double-stud framing, and resilient channel are the three common ways.
- Damping — a viscoelastic layer between two sheets of drywall dissipates sound energy as heat. Green Glue, QuietGlue, and factory-laminated products like QuietRock all work on this principle.
- Air sealing — sound travels through gaps. Outlet boxes, door undercuts, ductwork, and framing cracks all leak sound. Sealing is cheap and always worth doing.
You get the biggest jump by combining two or three of these. One alone doesn't move the needle much.
Common assemblies, ranked by cost/effect
Baseline — standard 1/2" drywall on 2x4 single-stud wall. Typical STC ~33. Normal speech is intelligible through it.
Good — 5/8" drywall both sides, fiberglass batt in cavity, caulked perimeter. STC ~39. Adds ~$0.75–$1.25 per board sq ft over baseline. Cuts the clarity of normal conversation enough to feel meaningfully quieter.
Better — double 5/8" drywall one or both sides with Green Glue between layers, batt in cavity. STC ~50–55. Adds ~$2–$3 per board sq ft. This is the sweet spot for residential — you can hear something but not words.
Best — staggered or double-stud framing, double 5/8" drywall each side, batt or mineral wool in both cavities, Green Glue between layers, acoustic sealant at perimeter. STC ~60+. Significantly more in framing labor and wall thickness (loses ~4" of room width). Gets you to "I only know the neighbor's TV is on because I can feel the bass."
Specialty — QuietRock or similar pre-laminated panels. Convenient for retrofits where you can't open the wall. Effective, expensive, and the installer has to know how to handle it (heavier, different screw schedule). We've used it successfully on condo corridor walls where framing changes weren't an option.
Where homeowners overspend
- Acoustic caulk everywhere. It matters at the perimeter of the wall and around outlet boxes; it does not matter in the middle of the drywall field.
- Green Glue between every surface. Two layers is meaningfully better than one. Three layers is not meaningfully better than two.
- Treating the wall while ignoring the door. A normal interior door is the weakest link — typical STC ~20. No wall assembly beats a door. If you need real quiet, spec a solid-core door with weatherstripping and a drop-seal.
- Retrofitting mass-loaded vinyl to finished walls. MLV works when installed properly under drywall. Adding it to a finished wall behind a second layer is expensive and usually lower-performing than just going double-drywall + Green Glue.
What to tell us on the bid
If you want an acoustic upgrade priced, give us:
- The goal in words, not just a number — "I don't want to hear normal conversation through this" is a different spec than "I want to hear almost nothing."
- Which walls (and ceiling, if relevant — floor-ceiling assemblies are their own conversation).
- Whether the wall is open or closed. Finished walls get retrofit assemblies; unfinished walls can use real decoupling.
- Door and duct plans. The whole room's weak link determines the achievable result.
We'll quote against a specific STC target, not a vague "soundproof" scope. That's what turns a "make it quieter" request into a number the GC and the owner can agree on.