How to Soundproof a Stud Wall: Acoustic Plasterboard and Insulation
A standard stud wall with a single layer of plasterboard each side and an empty cavity lets a lot of sound through. The good news is that a few well-chosen materials make a big difference, whether you're building a new partition or upgrading an existing one. This guide covers how sound gets through a stud wall, what Building Regulations ask for, and how acoustic plasterboard, insulation and resilient bar fit together.
Quick answer
- Fill the cavity with acoustic mineral wool, such as Rockwool RWA45 slabs or URSA acoustic roll.
- Add mass with soundboard, 15mm board or a second layer of board.
- Decouple one side with resilient bar so the board isn't fixed rigidly to the studs.
- Seal every gap with acoustic sealant. Small gaps let a surprising amount of sound through.
How sound gets through a stud wall
Airborne sound, such as voices or a TV, makes the board on one side vibrate. That vibration passes through the air in the cavity and through the studs to the board on the other side. So a better wall needs:
- Mass. Heavier linings vibrate less.
- Absorption. Mineral wool in the cavity soaks up sound, so less of it crosses the cavity.
- Decoupling. Separating the board from the studs, for example with resilient bar, breaks the direct path through the frame.
- Airtightness. Gaps at the perimeter, around sockets and at the head of the wall let sound bypass everything else.
What Building Regulations ask for
In England, Approved Document E sets a minimum laboratory sound insulation value of Rw 40 dB for new internal walls within dwelling-houses, flats and rooms for residential purposes (Table 0.2). It also gives example stud-wall constructions. The one with an insulated cavity (internal wall type B) is:
- a single layer of plasterboard on each side, each sheet with a minimum mass per unit area of 10kg/m²
- at least 75mm between the linings on a timber frame, or 45mm on a metal frame
- an absorbent layer of unfaced mineral wool batts or quilt, at least 25mm thick with a minimum density of 10kg/m³, in the cavity
- all joints well sealed
The other example (internal wall type A) leaves out the mineral wool but uses two or more layers of plasterboard on each side. Walls between separate homes (separating or party walls) have much stricter requirements, so get specialist advice for those. Wales has its own Approved Document E.
Acoustic insulation for the cavity
These are the manufacturers' published figures. Prices are ex VAT, at the time of writing:
| Product | Nominal density | Reaction to fire | Sizes we stock | Price |
|---|---|---|---|---|
| Rockwool RWA45 slab | 45kg/m³ | Euroclass A1 | 1200 × 600mm; 50, 75, 100mm | From £25.18 per pack |
| URSA ACOUSTIC ROLL | 22kg/m³ | Euroclass A1 | 25–100mm rolls | £39.48 for 50mm (14.4m²) |
| Rockwool Flexi slab | See datasheet | Euroclass A1 | 100 and 140mm | £41.36 for 100mm (4.32m²) |
| ODE Lunaflex APR HP roll | See product page | See product page | 25–100mm rolls | £29.90 for 50mm (12m²) |
Both RWA45 and URSA acoustic roll are well above the 10kg/m³ minimum density in the Approved Document E example. Choose a thickness that fits the stud depth without being compressed or leaving a large air gap. For example, use 50mm roll in a 50mm stud, or 70–75mm in a 70mm stud. Knauf Insulation and Isover also make acoustic partition rolls, but we don't stock them at the moment. The products above are the equivalents we sell now.
Acoustic plasterboard
Denser board adds mass. We stock Soundboard in 12.5mm (£12.49 per sheet) and 15mm (£14.58), ex VAT at the time of writing. Our soundboard is unbranded, so if you need its mass per unit area for a specification, ask us for the technical data before ordering. Adding a second layer of board, with the joints staggered, is another effective way to add mass. For more detail, see our sound plasterboard guide, and for sheet sizes, our guide to plasterboard sizes.
Building a new soundproofed stud wall
- Frame the wall. Fix floor and ceiling track and fit metal studs (or timber studs) at the centres your board needs, usually 600mm. Wider studs give a wider cavity, which helps. See our metal stud partition guide.
- Seal the perimeter. Run acoustic sealant under the track and where the wall meets the ceiling and existing walls.
- Board the first side. Use soundboard or 15mm board, fixed at the screw centres the board system specifies.
- Fill the cavity. Fit acoustic slabs or roll snugly between the studs, with no gaps.
- Add resilient bar on the second side (optional but effective). Fix resilient bar (£28.29 for 10 × 3m, ex VAT at the time of writing) horizontally across the studs. Screw the board to the bar only, not into the studs, or you'll bridge the gap you've created.
- Board the second side with the joints staggered from the first side. Add a second layer if you want more mass.
- Seal the gaps. Fill the gap at the base of the boards and around the perimeter with acoustic sealant, and avoid back-to-back sockets.
Our free drywall partition calculator works out studs, track, boards, screws and acoustic roll for your wall and prices them live.
Upgrading an existing stud wall
- If you can take the board off one side, fill the cavity with acoustic insulation and re-board with soundboard on resilient bar.
- If you can't open the wall, fix resilient bar over the existing board, screwing through into the studs, then add a new layer of soundboard fixed to the bar only.
- Either way, seal around the edges, sockets and switches. A door in the wall will limit the result, so a solid door with good seals helps.
Frequently asked questions
What's the best insulation for a soundproof stud wall?
Mineral wool made for the job, either dense slabs such as Rockwool RWA45 or acoustic partition roll such as URSA ACOUSTIC ROLL. Fill the cavity fully without compressing it.
Is acoustic plasterboard worth the extra cost?
Adding mass is one of the most effective upgrades. At the time of writing, 12.5mm soundboard is £12.49 per sheet against £9.16 for standard board (ex VAT). A second layer of standard board is the alternative.
Does loft roll work for soundproofing?
Any mineral wool in the cavity is better than none. Acoustic rolls and slabs are made to fit stud widths, and the denser products are the ones specified for acoustic walls.
Will this work on a party wall?
Party walls between homes are a different construction with much higher requirements. Get specialist advice rather than relying on an internal-wall upgrade.
Order acoustic materials
Browse our acoustic mineral wool, plasterboard and resilient bar and angles. Prices are shown ex VAT. We are delivery only (no collection) and deliver to mainland England and Wales, with a £400 ex VAT minimum order and free delivery on every order (see delivery information). Call us on 03330 908479 (Mon–Thu 8am–5pm, Fri 8am–12pm), email sales@insulationwarehousedirect.co.uk, or order online.
Sources: Approved Document E (GOV.UK), Table 0.2 and paragraphs 5.17–5.18; Rockwool RW Slabs datasheet; Rockwool Flexi datasheet; URSA ACOUSTIC ROLL datasheet. Figures are indicative and correct at the time of writing.