Party wall / shared wall sound insulation

What is party wall sound insulation?

Party wall sound insulation is a multi-layer acoustic build-up applied to one or both faces of the shared partition between two independent units (flats), upgrading its airborne sound transmission performance. Most of the Turkish housing stock has a party wall built from 100-200 mm hollow brick, performing around Rw 36-42 dB — a level at which neighbour speech is clearly intelligible.

Main sources of neighbour noise

• Speech and TV — mid/high frequency, easy to attenuate
• Music bass — low frequency, controlled only by mass and air gap
• Domestic appliances (mixers, vacuum cleaners) — impulsive noise
• Children and furniture movement — combined airborne + structure-borne

Target performance

The acceptable minimum for Turkish housing is Rw 50 dB; for true comfort we recommend Rw 55+ dB. At this level normal speech is inaudible and only the heaviest bass remains faintly audible.

Application methods

1. Single-side reinforcement (most common)

Applied without demolishing the existing wall, only on the disturbed side:

• Vibroacoustic hangers + 60-80 mm rock wool
• Double acoustic plasterboard + interlayer elastomer membrane
• Gain: 18-25 dB additional Rw

2. Independent double-leaf stud system

For the highest performance:

• Independent steel studs 30-40 mm clear of the existing wall
• Two cavity infill layers and four plasterboard layers
• Gain: 25-35 dB additional Rw

Flanking transmission — the hidden enemy

Even with a perfectly insulated party wall, sound can still flank through side walls, floor or ceiling. Flanking transmission can lower the overall result by 5-15 dB. Our site survey identifies these paths and we add corner or perimeter treatment where required.

Time and cost

A typical party wall (15-20 m²) takes 2-3 days. Investment depends on target Rw and wall area; a written quotation follows the site survey. In our experience, party-wall insulation pays back quickly through the value it adds to the flat.

Materials we use

• Certified vibroacoustic hanger system
• High-density rock wool (min. 70 kg/m³)
• Double acoustic plasterboard (different thicknesses)
• Elastomer membrane (Tecsound)
• Acoustic sealant + flexible perimeter tape

Field story

On a recent housing project in Kadıköy, Istanbul we measured Rw 38 dB on the party wall and reported Rw 60 dB after our intervention. The owner's feedback: "for the first time I could sleep with the window closed." For more detail see our What is sound insulation? guide.