An Overview of Approved Document E

Approved Document E (Resistance to the Passage of Sound) details the soundproofing standards required to pass building regulations for new homes, refurbishments and conversions whereby a building with a previously different use is becoming a dwelling (England and Wales).

Part E applies to all dwellings including attached houses, flats and rooms for residential use such as student and nursing accommodation, as well as any common areas, for example, in apartment buildings or schools.

In this article we’ll be outlining what Part E is, why it is important and how soundproofing can help you pass Part E building regulations.

‘Dwelling House’ or ‘Rooms For Residential Purposes’?

A dwelling house is, according to the government’s planning portal:

“A self-contained building or part of a building used as a residential accommodation, and usually housing a single household. A dwelling may be a house, bungalow, flat, maisonette or converted farm building.”

A room for residential purposes is:

“[A] room, or a suite of rooms, which is not a dwelling house or flat and which is used by one or more persons to live and sleep and includes a room in a hostel, a hotel, a boarding house, a hall of residence or a residential home, but does not include a room in a hospital, or other similar establishment, used for patient accommodation.”

What is Part E?

Part E aims to reduce noise transmission between neighbouring homes as well as between internal spaces. Regulations protect residents from the noise of activities in other rooms or adjoining properties in order to avoid tension.

There are also provisions outlined in Approved Document E that apply to common areas of residential buildings. These include corridors and stairwells, for example, in hotels and apartment buildings. It is imperative that there are sound absorptive treatments implemented, as noise reverberation needs to be controlled in order to pass Part E regulations.

Approved Document E is divided into four main sections:

  • E1 Protection against sound from other parts of the building and adjoining buildings
  • E2 Protection against sound within a dwelling house, etc
  • E3 Reverberation in the common internal parts of buildings containing flats or rooms for residential purposes
  • E4 Acoustic conditions in schools

It is E1, E2 and E3 we’ll be looking at.

How is sound assessed?

There are two types of noise transmission that Part E refers to. These are Airborne Sound and Impact Sound.

Airborne Sound – this applies to sounds transmitted through the air. Examples include talking, television and appliance noise.

Impact Sound – this applies to sounds that are structurally borne. Examples include footsteps and moving furniture.

In order to pass building regulations, completed buildings and conversions need to be able to provide proof of meeting Part E building regulations.

What are the acoustic performance regulations?

For purpose built dwelling houses, Part E demands 45dB (decibels) of airborne sound insulation for walls, floors and stairs; and 62dB of impact sound insulation for floors and stairs.

If the dwelling is not purpose built but has undergone ‘a material change of use’ (i.e. it used to be a warehouse, school, church, prison, factory, office, etc), Part E demands 43dB (decibels) of airborne sound insulation for walls, floors and stairs; and 63dB of impact sound insulation for floors and stairs.

For rooms with a residential purpose, the same performance is required, with the exception of walls, which must have an airborne sound insulation performance of 43dB.

What is reverberation?

‘Reverberation’ is, essentially, another word for ‘echo’, the reflection of sound from a hard surface. The simplest way to describe the difference is that with an echo, there is no overlap with the original sound, whereas with reverberation there is. As such, reverberation is a more disorienting effect than an echo.

In the common areas of residential properties, such as corridors and stairwells, the ‘reverberation time should be less than 1.5 seconds’. This is considerably less arduous than the requirement for schools, which ranges from 0.6 to 0.8 of a second.

The reverberation time of a room or space is defined as the time it takes for sound to decay by 60dB. For example, if the sound in a room took 10 seconds to decay from 100dB to 40dB, the reverberation time would be 10 seconds. This can also be written as the T60 time.

How does the decibel system work?

The lowest sound on the decibel scale is 0dB, which equates to near silence. A sound that is 10 times greater in intensity will be measured as 10dB. A sound 100 times more intense than 0dB is measured as 20dB, and a sound that is 1000 times more intense than 0dB is 30dB.

Even though the intensity is being increased by 10 times as much, the decibels are only increased by a factor of 10.

Here are the basic rules of how to work with the decibel scale;

Change in dB Change in sound intensity/energy
An increase of 3 dB Doubled
A decrease of 3 dB Halved
An increase of 10 dB Increased by a factor of 10
A decrease of 10 dB Decreased by a factor of 10
An increase of 20 dB Increased by a factor of 100
A decrease of 20 dB Decreased by a factor of 100

How are Part E tests carried out?

There are two means of establishing whether or not a dwelling house or room for residential purposes is compliant with Part E.

The main method is ‘pre-completion testing’ (PCT). The testing times are negotiated between building control bodies and the developers, and testing is carried out once the dwellings on either side of a separating element are essentially complete.

The testing must be carried out by a third party with appropriate accreditation (e.g. UKAS). They measure the decibels of airborne and impact sound that can be heard from one room to the next.

The other approved method of achieving compliance is ‘robust detail’. Robust Details Ltd was formed due to the housebuilding industry’s request for an alternative to PCT.

The scheme is used for new adjoined dwellings but is not applicable for conversions, home extensions or building refurbishments. This involves following a pre-approved build-up in order to achieve the necessary sound insulation levels.

Robust Details are high performance separating wall and floor constructions that are capable of consistently exceeding the relevant regulatory performance standards and expected to be sufficiently reliable not to need the check provided by PCT.

The responsibility lies with the builders of the constructions. It is their duty to demonstrate that the required levels of sound insulation have been achieved through executing pre-completion testing of the built construction on site.

Approved Document E requires 1 in 10 constructions be tested.

How do you pass Part E Building Regulations?

Different materials offer different capabilities when it comes to soundproofing, which means it can be beneficial to use a combination of materials in order to block airborne sound.

Adding insulation to walls is essentially adding mass to them, which works to block any unwanted noise. If you are unsure which materials and insulation to use, we always recommend speaking to a specialist.

When it comes to flooring, the most effective soundproofing comes from the addition of high-density soundproofing mats. The most common floor types to use are concrete and wooden timber beams when soundproofing to meet Part E regulations.

In order to meet Part E regulations you need to increase the mass of the floor with soundproofing mats as these improve the absorption of vibrations to combat impact noise whilst still controlling airborne noise.

It is rare that you would need soundproofing for ceilings. Their soundproofing usually comes from the floors above as absorbing impact noise from the source is much more effective.

There are some circumstances where the ceilings need to be soundproofed, for example, if a shop below a flat is being converted into a dwelling. This conversion would have to pass Part E regulations.

How could you fail Part E regulations?

The most common cause of failure to meet Part E building regulations comes down to a poor system.

Sound will always look for the weakest point in order to make its escape. If a soundproofing system has been successfully installed and the building still doesn’t pass building regulations, then this can be due to flanking sound transmission.

What is flanking?

Approved Document E defines ‘flanking transmission’ as, ‘Sound transmitted between rooms via flanking elements instead of through separating elements or along any path other than the direct path’. A flanking element is ‘Any building element that contributes to sound transmission between rooms in a building that is not a separating floor or separating wall’.

Sound will always try to seek an alternative path. This could be along materials shared by adjacent structures, through air pockets in joist cavities, or along other rigid surfaces such as pipes and glass.

How do you stop flanking transmissions?

One of the most effective methods to stop flanking sound is to use isolation strips around the perimeter of the partitions at the edges of floors and walls. Structurally borne flanking noise is the most common cause of failure, so isolation strips are a great way to avoid flanking transmissions.

Making use of floating floors is another great way to prevent flanking sound. A floating floor incorporates a layer of materials such as rubber or fibreglass and helps to absorb vibrations.

Another effective way to help seal perimeter gaps is to use soundproof acoustic sealant which is a type of caulking. Sealing the gaps, cracks and crevices in the perimeter reduces flanking vibrations.

When it comes to soundproofing, there are a number of products that can help you pass Part E building regulations. Consulting a specialist is the best way to learn what will work best for your project.


In summary, Part E building regulations apply to all dwellings (including temporary) with the exception of hospital rooms or similar. The regulations aim to reduce the transmission of sound between adjoining rooms in order to decrease tension between residents.

Part E regulations look at sound insulation performance for both airborne and impact sound. Airborne and impact sound are sounds transmitted through the air, and those that are structurally borne. You can read the full Part E building regulations here.

Testing of Part E can be done pre-completion by a UKAS-approved (or similar) third party. However, new buildings can use Robust Details separating walls and floors as they are designed to exceed relevant regulatory performance standards.

The main cause of failure to pass Part E is flanking transmissions. This can be avoided with the proper soundproofing and insulation measures.

Speak to one of our specialists to find out which methods of soundproofing are most appropriate and effective for your project.