What This Requirement Covers
While Approved Document E focuses on sound insulation between dwellings, there are no mandatory requirements for sound insulation within a single dwelling. However, good internal sound insulation significantly improves the quality of life for occupants, particularly in open-plan designs and between bedrooms and living areas.
Key Requirements
Good Practice Standards
Although not required by Building Regulations, the following are recommended
- Internal walls between bedrooms: Rw 40-45 dB (a single layer of plasterboard on each side of a timber stud with mineral wool in the cavity achieves approximately Rw 40 dB)
- Internal wall between bedroom and bathroom: Rw 40-45 dB (to reduce the transmission of running water and toilet flushing)
- Internal floor between living room and bedroom above: Rw 40-45 dB airborne, with impact sound treatment
Common Noise Issues Within Dwellings
- Waste pipe noise: WC discharge pipes running through walls or floor voids adjacent to bedrooms
- Boiler and heating noise: Boiler cycling, pump vibration, and pipe expansion
- Bathroom fan noise: Extract fans transmitting noise through ductwork
- Impact noise from hard floor coverings: Hard floors (tile, laminate, engineered wood) on upper storeys transmitting footstep noise
Simple Improvement Measures
- Stud walls: Add mineral wool insulation (50-100 mm) between studs; use two layers of plasterboard on at least one side
- Pipe isolation: Use acoustic pipe wrapping and resilient pipe clips for waste pipes running through walls or floors
- Floor covering: Use underlay or acoustic mat beneath hard floor coverings on upper storeys
- Door upgrade: Replace lightweight hollow-core internal doors with solid-core doors (25 kg or heavier)
Practical Compliance Tips
- Consider internal sound insulation at the design stage, not as a retrofit
- The cheapest and most effective improvement is adding mineral wool to stud wall cavities and using heavier plasterboard
- Route waste pipes away from bedrooms where possible; where unavoidable, wrap pipes with acoustic lagging
- Specify solid-core internal doors for bedrooms; they are significantly better at reducing noise than hollow-core doors
- If upper-storey hard flooring is desired, use a high-quality acoustic underlay to reduce impact noise to the room below
- Brief plumbers and heating engineers on the importance of acoustic isolation for pipes and equipment
- Consider the acoustic impact of open-plan layouts; sound travels freely through open spaces