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Part E - Resistance to Sound


Approved Document E of the Building Regulations (England and Wales) deals with ‘Resistance to the Passage of Sound’. The regulations cover all types of dwellings, including hotels, hostels, halls of residence and residential homes. Their purpose is to protect residents from the noise of neighbours in other parts of the building or in attached buildings.

Section 5 (Scotland)
The majority of the measures adopted in Section 5 (Scotland) mirror those stated in Part E Building Regulations (England and Wales). Variations in the legislation are:
1. Minimum values of airborne sound transmission for walls and floors vary.
2. Maximum values of impact sound transmission for floors vary.
3. Low frequency sound values (Ctr frequency correction factor) do not apply in Scotland.  
4. Robust Details do not apply in Scotland. However, the Technical Standards in Scotland state that specific constructions must be adhered to where Pre-Completion Testing is not carried out.
5. Section 5 Technical Standards require adequate levels of insulation to prevent sound transmission from adjoining buildings and between parts of the same building.


When approaching a noise control problem, the difference between sound absorption and sound insulation should be appreciated.

Sound absorption
Sound absorption refers to the depletion of reverberant noise within the same room or area as the noise source. This normally involves lining all or part of the room surfaces with a material which absorbs sound.

Sound insulation
Sound insulation, otherwise known as sound reduction, is the prevention of noise being transmitted from one part of a building to another, for example by erecting a partition or wall. When considering sound insulation in existing buildings, there are three methods of sound transmission which need to be considered:

- Airborne sound
- Impact sound
- Flanking sound

Airborne sound
Airborne sound sources produce noise by vibrating the air immediately around them. Typical sources include the human voice, musical instruments, home entertainment systems and noisy dogs.

Impact sound
Impact sound sources produce noise by direct physical contact with part of a building. Examples include slamming doors, stamping on the floor and vibrating washing machines.

Flanking sound
Flanking sound transmission usually refers to sound that travels through two structural elements that meet such as the external wall that joins a separating wall between two dwellings. Flanking sound can also include sound that travels along unintended air paths, such as unsealed gaps in the structure and around service penetrations.

Performance standards
This table sets out the performance standards for England, Wales and Scotland. 


Built to Robust Detail (RD) [England, Wales & Scotland]

 New-Build Only
Airborne Sound (Walls & Floors)   ≥47 dB (DnT,w+Ctr)
 Impact Sound (Floors) ≤60 dB (LnT,w)

Built Using Pre-Completion Testing (PCT) [England & Wales]

 New-BuildChange of Use
Airborne Sound (Walls & Floors)  ≥45 dB (DnT,w+Ctr) ≥43 dB (DnT,w+Ctr)
Impact Sound (Floors)≤62 dB (LnT,w)≤64 dB (LnT,w)

Built Using Pre-Completion Testing (PCT) [Scotland] 

 New-Build & ConversionsTraditional Buildings
Airborne Sound (Walls & Floors) >56 dB (DnT,w+Ctr)>48 dB (DnT,w+Ctr)
Impact Sound (Floors)<56 dB (LnT,w)<58 dB (LnT,w)



dB (decibel)
Unit of measure in acoustics that indicates the loudness of sound

Weighted sound reduction index. Laboratory measure of airborne sound transmission

DnT,w + Ctr
Site measure of airborne sound with low frequency correction applied (higher figure = better performance)

Laboratory measure of the impact sound level (lower figure = better performance)

Site measure of the impact sound level (lower figure = better performance)



Buildings must be tested for sound transmission before completion to check that they meet or exceed Part E standards.

The Regulations require that one in ten of each construction type should be tested. Tests are at the Building Inspector’s discretion. If a building fails its test, the sound insulation will have to be improved and followed up with a fresh test for that construction type.

The only exceptions are for constructions that conform to a Robust Detail document (RD). These are constructions that are built to a pre-approved construction detail and therefore do not require on-site testing.



A Robust Detail, for Part E of the Building Regulations, is a separating wall or floor construction which has been assessed and approved by Robust Details Limited.

In order to be approved, each Robust Detail must:
• Be capable of consistently exceeding the performance standards given in Approved Document E to the Building Regulations for England and Wales
• Be practical to construct on-site
• Be reasonably tolerant to workmanship
If you build to Robust Detail, you don’t have to carry out Pre-Completion Testing. Each Robust Detail has its own site work checklist. These are designed to help builders, building control bodies, new home warranty providers and others to ensure that building work is carried out exactly in accordance with the Robust Detail specifications.

Approved Document E Ways to comply

  • Robust Details (RDs): RD Approval Constructions: New-build houses and apartments only
  • Pre-Completion Testing (PCT): Guidance & Proprietary Systems: All houses, apartments and all buildings with rooms for residential purposes. New-build or conversion.


What is tested?
Walls are tested for airborne sound, how much noise they insulate from one side of the wall to the other, i.e. sound insulation. Floors are tested for airborne noise in a similar way to party walls. They are also tested for impact which is designed to simulate footfall.

Why is acoustic testing needed?
Approved document E in England and Wales sets out the levels of acceptable noise in different buildings. Pre-completion site testing or Robust Detail licensing is therefore required for party walls and floors in new-build dwellings and conversions buildings to demonstrate their performance. The test requirements vary depending on the construction.

Which acoustic testing and how many tests are needed?

1 in 10 houses of the total number of attached houses on a site require a set of tests. A set includes airborne wall tests.

1 in 10 flats of the total number of flats on a site require a set of tests. A set includes 2 airborne wall tests, 2 airborne floor tests and 2 impact floor tests.

Rooms for residential use (hotels, care homes, student accommodation):
Require a set of tests for 1 in 10 of the total number of rooms on the site. This includes 1 airborne wall test, 1 airborne floor test and 1 impact floor test.

How is testing done?

Airborne sound
Specialist equipment is used to measure sound insulation of party walls and floors. This is done by taking a series of readings in rooms on both sides of the wall (as well as background noise levels and reverberation times) to calculate the reduction in sound levels.

Impact floor test
This simulates footfall, using a tapping machine impacting the floor and measuring the noise levels below the floor. This test is performed on the structural floor before any soft covering is installed.