Sound Insulation Calculator — Acoustic Materials for Part E

UK Building Regulations Approved Document E sets minimum sound insulation standards between dwellings. For walls separating dwellings, the minimum airborne sound insulation is 45 dB DnT,w + Ctr. For floors separating dwellings, the minimum airborne insulation is 45 dB DnT,w + Ctr and the maximum impact sound is 62 dB L'nT,w. New-build properties must also pass pre-completion testing.

Resilient bars (such as Gypframe RB1) are thin metal channels fixed across studs or joists at 600mm centres to decouple the plasterboard from the structure, reducing sound transmission. Soundbreaker bars (such as Mute Soundbreaker bars) provide a deeper isolation channel with better acoustic decoupling. Soundbreaker bars typically achieve 5-8 dB better performance than standard resilient bars, which can be the difference between passing and failing Part E.

For stud walls between dwellings, 100mm thick acoustic mineral wool (density 45 kg/m³ minimum, such as Rockwool RWA45 or Knauf Acoustic Slab) is recommended to fill the cavity completely. For timber floor/ceiling constructions, 100mm is also standard between joists. Enhanced systems may use higher-density products (60-80 kg/m³) for better low-frequency performance. Use our Insulation Thickness Calculator for thermal insulation requirements.

Acoustic plasterboard (such as British Gypsum Gyproc SoundBloc or Siniat Silent Board) is denser than standard plasterboard, typically 12.5mm thick at around 10-12 kg/m² compared to 8-9 kg/m² for standard board. For Part E compliance, acoustic plasterboard is recommended. For enhanced performance, two layers of acoustic plasterboard with staggered joints provides significantly better results.

Sound travels through the weakest point in any construction. Even small gaps around the perimeter of a wall or floor can dramatically reduce the overall sound insulation. Acoustic sealant (such as Soudal Acoustic Sealant) fills these gaps and remains flexible, maintaining the acoustic seal as the building moves. It should be applied around all perimeter edges, at board joints, and around any service penetrations.