How to soundproof a wall

Inspired by Jim Prior's soundproofing guide. This walkthrough is based on the UK video "7 ways to Soundproof a wall" by Jim Prior, who is the UK's leading specialist in home soundproofing. Jim has been featured in The Sunday Times and on BBC Radio - he really does know this inside out. Well worth a watch to understand which system fits your situation before you buy anything.

1. Work out what kind of noise you're dealing with

There are two types: airborne noise (voices, TV, music - sound travelling through the air and then the wall) and impact noise (footsteps, furniture being moved - vibration travelling through the structure). Most party wall problems are airborne. Both need slightly different approaches.

Also check: is the noise coming through the wall itself, or actually coming around it - through the ceiling, floor, or a shared void? A gap around a soil pipe or a shared loft space can let more sound through than the wall itself. That said, in most terraced and semi-detached houses in East Kent, the party wall is where the bulk of the noise travels.

2. Understand the two principles that actually work

Mass and decoupling. Mass means adding weight - heavier walls transmit less sound. Decoupling means creating a break in the structure so vibration can't travel directly from one side to the other.

A single layer of dense plasterboard adds mass. An independent stud wall with a gap between it and the party wall adds decoupling. The best systems combine both. Acoustic foam tiles and egg boxes do very little - they absorb echo inside a room, not sound coming through a wall.

3. Choose your system

For a budget approach with minimal room loss: add one or two layers of acoustic-grade plasterboard (heavier and denser than standard board) directly over the existing wall. Fix on resilient bars rather than directly onto battens - the bars flex slightly and break the vibration path. This can knock off a reasonable amount of noise for relatively little cost.

For a proper result: build an independent stud wall 25–50mm off the party wall, fill the cavity with acoustic mineral wool, and line both sides with two layers of acoustic plasterboard. This is the system most soundproofing professionals use. It loses a bit of room width but the results are noticeably better.

4. Prepare the wall

Fill any cracks or gaps in the existing wall before you build anything on top. Sound finds gaps. A small hole around a pipe penetration or a crack at the skirting board can carry surprising amounts of noise - seal them with acoustic mastic (not ordinary decorator's caulk, which stays elastic and can transmit vibration).

Remove skirting boards and architrave. You're better fitting new ones after the new wall face is in place.

5. Fix resilient bars or build the independent frame

For a direct-fix system: screw resilient bars horizontally across the wall at 600mm centres. The bars are C-shaped metal channels that flex when vibration hits them, breaking the sound path. Screw them into the wall through one flange only - the other flange floats free. Never bridge the bars or short-circuit them with direct fixings.

For an independent stud wall: mark out the floor and ceiling plate positions with the wall at least 25mm clear of the party wall. Build a standard stud frame - 100mm C studs at 400mm or 600mm centres. Make sure it's self-supporting and doesn't touch the party wall at all.

6. Fill the cavity with acoustic mineral wool

Cut acoustic mineral wool batts to fit snugly between the studs or into the cavity. This isn't ordinary loft insulation - it's denser, usually 45–60kg/m³. It absorbs the sound energy travelling through the air gap so it can't excite the second wall face.

Wear gloves and a dust mask. The fibres aren't pleasant. Pack the batts firmly but don't compress them - compressed wool loses some of its acoustic properties.

7. Board with two layers of acoustic plasterboard

Acoustic plasterboard is heavier than standard - typically around 12.5kg/m² versus 8–9kg/m² for a standard board. Hang the first layer with joints staggered, then add the second layer with the joints offset from the first by at least half a board width.

Fix into the resilient bars or stud frame only - never directly through to the party wall. Use acoustic sealant along all perimeter edges where the new wall meets the floor, ceiling, and side walls. These junctions are where sound sneaks through in most DIY attempts.

8. Seal every junction and penetration

Run acoustic mastic along the base of the new wall where it meets the floor, and along the top where it meets the ceiling. Any electrical sockets or switch backs need acoustic putty pads behind them - a socket box in the wall is essentially a hole in your soundproofing otherwise.

Fit new skirting boards and architrave, then skim or tape-and-joint the boards to a paintable finish. The difference will be noticeable - not silence, but a meaningful reduction in what you hear. Mind you, if the noise is very loud to start with, "meaningful reduction" still leaves some noise. Manage expectations.

When to call a handyman

Call Richard if you want the independent stud wall approach done properly. Getting the frame free-standing, the resilient bars correctly fitted, and all junctions properly sealed is fiddly work - each shortcut you take in acoustic work costs you performance you paid for.