Soundproof Plasterboard: UK Guide

What is soundproof plasterboard?

Soundproof plasterboard (also called acoustic plasterboard or high-density board) is manufactured with a denser gypsum core than standard plasterboard. The increased mass helps block airborne sound. It looks identical to standard board but weighs 30-50% more.

Common UK brands include British Gypsum SoundBloc (blue edge), Knauf Soundshield (purple edge), and Siniat Acustic (green edge). All work on the same principle: higher mass equals better sound insulation.

Acoustic board alone provides modest improvement (3-6dB reduction). For significant noise control, combine it with resilient bars, acoustic insulation, and proper detailing at edges and penetrations.

How acoustic plasterboard works

Sound travels through walls as vibration. Heavier materials require more energy to vibrate, so they block more sound. Standard 12.5mm plasterboard weighs around 8-10kg/m². Acoustic board at the same thickness weighs 12-14kg/m², providing 40-50% more mass.

The improvement is measured in decibels (dB). A 3dB reduction means sound energy is halved. A 6dB reduction means sound energy is quartered. Human perception is logarithmic: a 10dB reduction sounds roughly half as loud.

Acoustic board provides 3-6dB improvement over standard board in the same construction. This is meaningful but not transformative. For party walls needing 45dB+ reduction (Building Regulations Part E), you need multiple layers, resilient mounting, and cavity insulation.

Types and specifications

Standard acoustic board (12.5mm)

Most common thickness. Weighs around 13kg/m² (vs 10kg/m² for standard board). Provides 3-4dB improvement. Suitable for single-layer installations on resilient bars or double-layer party walls. Costs £12-15 per 1200x2400mm sheet.

Enhanced acoustic board (15mm)

Heavier and denser. Weighs 15-16kg/m². Provides 4-6dB improvement. Used where higher performance is needed and extra weight is acceptable. Common in commercial buildings. Costs £15-18 per sheet.

Fire and acoustic combined

Boards that provide both enhanced fire resistance and acoustic performance. Used in flats and commercial buildings where both properties are required. Check datasheets for specific ratings (typically 60 minutes fire, 3-5dB acoustic improvement).

Performance and dB reduction

Sound insulation is measured as weighted sound reduction index (Rw). Higher Rw means better performance. UK Building Regulations Part E requires minimum Rw 45dB for party walls and floors in new builds.

The wall system matters more than the board alone. Acoustic board on poorly detailed studs performs worse than standard board on a properly designed resilient system.

Installation tips for best performance

Use resilient bars or channels

Mount the plasterboard on resilient metal bars fixed to the studs. The bars decouple the board from the frame, preventing vibration transmission. This adds 5-10dB improvement on top of the board's own mass benefit.

Fill the cavity with acoustic insulation

Install mineral wool or acoustic insulation batts between the studs. This absorbs sound energy in the cavity and prevents it resonating. Adds 8-12dB improvement. Essential for meeting Part E.

Seal all gaps and penetrations

Sound leaks through the smallest gaps. Seal edges with acoustic sealant (not standard decorator's caulk). Use acoustic putty pads around electrical boxes. Fit acoustic gaskets behind skirting boards. A 1mm gap around the perimeter can halve the wall's performance.

Use double layers where needed

For party walls or high-performance installations, use two layers of acoustic board with staggered joints. The second layer covers the joints of the first, eliminating weak points. Adds 3-5dB improvement over single layer.

Avoid rigid connections

Do not fix items directly through the board into the studs (shelves, TVs). Use floating fixings or accept that heavy fixings will compromise acoustic performance. Every screw through the board into the stud creates a sound bridge.

When to use acoustic plasterboard

Party walls and floors (flats, semi-detached, terraced)

Building Regulations require minimum sound insulation between dwellings. Acoustic board is almost mandatory in new builds. Use double layer on staggered studs or resilient bars, with 100mm mineral wool in the cavity.

Home offices and studios

Reduces noise escaping from the room (important if you record audio or take video calls). Also reduces noise entering (useful if the office backs onto a busy road or living room).

Bedrooms backing onto noisy areas

Bedrooms next to staircases, bathrooms, or external walls facing roads benefit from acoustic board. The extra cost is small relative to the comfort improvement.

When standard board is fine

Internal partitions in the same dwelling (bedroom to hallway) do not need acoustic board. Save the money unless noise is a specific concern.

Cost and budget

Acoustic plasterboard costs 30-60% more than standard board:

• Standard 12.5mm plasterboard: £6-8 per sheet
• Acoustic 12.5mm plasterboard: £12-15 per sheet
• Acoustic 15mm plasterboard: £15-18 per sheet

For a typical 3m x 2.4m party wall (7.2m²), you need 3 sheets per side. Single layer both sides: 6 sheets x £13 = £78 (vs £42 for standard board). Double layer both sides: 12 sheets x £13 = £156.

Add costs for resilient bars (£40-60 for a 3m wall), acoustic insulation (£20-30), and acoustic sealant (£10-15 per tube). Total material premium for a party wall: £100-150 over standard construction.

The improvement is worth it. Poor sound insulation causes complaints, stress, and reduced property value. Building Regs compliance is mandatory in new builds and conversions.

Acoustic board vs other soundproofing methods

Mass-loaded vinyl (MLV)

Heavy flexible sheet (5-10kg/m²) fixed behind plasterboard. Effective but expensive (£15-25/m²). Used where space is limited and maximum performance is needed.

Additional layer of standard board

Two layers of standard 12.5mm board (20kg/m² total) provide similar mass to one layer of 15mm acoustic board (16kg/m²). Cheaper but thicker. More labour to install two layers.

Separate stud walls

Build two independent stud frames with a gap between. Maximum acoustic separation but loses 100-150mm of room width. Used in recording studios and cinemas.

For most domestic applications, acoustic plasterboard on resilient bars with cavity insulation offers the best balance of performance, cost, and space efficiency.

Related guides

• Plasterboard: Complete Guide
• Plasterboard Sizes UK
• Insulated Plasterboard Guide
• Plasterboard Jointing Techniques