Sound Insulation Testing and Acoustic Design Detailing

Part E of Building Regulations for new build and converted developments require sound insulation standards to be achieved. APT Sound Testing can provide acoustic advice and guidance on how best to achieve these standards and pass the Pre-completion sound insulation testing, either by assessing the current acoustic design detailing and specifications or undertaking a site visit to advise on how to achieve the sound insulation design criteria.  We can then provide pre-completion sound testing and a Building Control compliant report at the end of the project to achieve project signoff.

Sound insulation acoustic design detailing

In our experience, specifying acoustic details for party walls, floors, construction junctions and service penetrations can be quite difficult and if not done correctly can be difficult and expensive to put right. APT Sound Testing can help you design your project so that it meets the requirements of Approved Document E without sound testing failure and the subsequent need for expensive and time-consuming remediation work. We have experience of the acoustic design of all types of wall and floor constructions and are able to advise on standard specifications to help reduce buildability issues and cost; however, where required we are also to able to develop bespoke details for wall, floor and ceilings where a ceiling and floor upgrade is not possible. Please visit our acoustic design page for more information. 

Why Choose APT to undertake your Part E Sound testing?

APT Sound Testing is a UKAS accredited sound testing laboratory, employing our own testing engineers – we do not use subcontractors. As we directly employ a large number of our own engineers, it allows us continue to provide the highest quality sound testing and quickly provide sound insulation testing suitable for Building Control approval.  If you are unsure about sound insulation testing and how many tests you think you need, give 

What is sound insulation testing for Part E?

Sound insulation testing for Part E, or Pre-completion sound testing as it is also called, is a method of testing a party floor or party wall (also known as separating floors/walls) to show that their acoustic properties meet the minimum acoustic standards set out in Approved Document E. These tests have to be carried out in accordance with certain standards and testers should be UKAS accredited. Download our brief guide to what happens during a sound insulation test. Please download our sound testing checklist for more information.  

What is Airborne Sound Testing? 

Airborne sound insulation testing to BS EN ISO 140-4 is carried out using the following testing methodology and is carried out between two rooms using virtually the same way, whether the test takes place vertically (across a party floor) or horizontally (across a party wall). Basically, a dodecahedron loudspeaker and power amplifier are used to generate high levels of ‘pink’ noise in the source room which is measured using a UKAS defined test method in both the source room and the receiver room. The loudspeaker speaker is then moved to a second position in the source room and the measurements repeated. The background noise level is measured in the receiver room and the reverberation time undertaken in the receiver room, using bursts of pink noise. This process provides all the measurement data necessary to calculate DnTw + Ctr in line with Approved Document E.

What is Impact Sound Testing? 

Impact sound insulation testing to BS EN ISO 140-7 is carried out using the following testing methodology to floors. Firstly, a tapping machine is used to generate impact sound to the floor, and the measurements taken in the room directly below. The impact test is different to the airborne test which measures the sound level difference (i.e., the noise level in the source room minus the noise level in the receiver room) The impact sound test measures the absolute noise level in the receiver room generated by the tapping machine hammers hitting the floor, which is why a lower value is better. The background noise levels and reverberation times are measured in the receiver room (the same as airborne testing) to allow the L’nTw to be calculated in line with Approved Document E.

What sound insulation performance does my development have to achieve?

Approved Document E stipulates the performance you need to achieve for each type of dwelling. The requirements usually depend on whether the dwelling is a new-build or formed by a material change of use e.g., a conversion project. There is also a slight variance if you have a project containing rooms for residential purposes e.g., student accommodation or hotel rooms and HMO. student accommodation etc) rather than dwellings such as houses or flats. 

Usually, the minimum airborne sound insulation performance for new-build party walls and floors is 45 dB DnTw + Ctr and for conversions is 43 dB DnTw + Ctr. The requirement for impact sound insulation on new-build floors is a maximum L’nTw of 62 dB; and for conversions the maximum value is 64 dB L’nTw. It’s worth noting that for airborne sound insulation, the performance requirement is a minimum value i.e. your result needs to 45 dB DnTw + Ctr or above and for impact sound insulation the performance requirement is a maximum value i.e. L’nTw of 62 dB or lower to pass. 

How many Sound tests are needed on your project?

The number of sound tests you will need for your project, depends on the number of units /adjacent dwellings and the different types of construction used. Approved Document E recommends as a minimum that one set of tests (1 x 6 pack) is undertaken for every ten dwellings of the same type and same construction – this usually allows for 2 airborne wall, 2 airborne floor and 2 impact floor tests. The number of individual tests in a set of tests varies but is usually no more than six sound tests per set in total. 

For a block of flats containing up to 10 dwellings the sound testing schedule should look similar to this: 

• Two airborne tests on party walls (one bedroom to bedroom & one lounge to lounge)

• Two airborne tests on party floors (one bedroom to bedroom & one lounge to lounge)

• Two impact tests on party floors (one bedroom to bedroom & one lounge to lounge)

For a pair of semi-detached houses, the sound testing schedule should look similar to this: 

• Two airborne tests on party walls (one bedroom to bedroom & one lounge to lounge)

At what stage is the sound testing carried out?

To give your-self the best chance of passing the sound testing, all the dwellings need to fully complete, in terms of walls, floors, ceilings, windows, doors must be installed. Also, secondary items such as trickle vents, door seals, electrical sockets and switches must also be installed. It is worth noting that tests on floors must be conducted without soft coverings such as carpet and/or foam backed vinyl etc. installed. For more information on correct site conditions needed to complete a sound insulation test, please read our sound test checklist guide for more information.

What happens if the property fails the sound testing?

If a party wall or floor does not meet the minimum performance requirements of Approved Document E, Building Control will usually ask for remedial work to upgrade the acoustic construction of the party wall/floor and after the works are completed, another set of sound test/s to facilitate a pass to attain Building Control sign off. 

Using our acoustic design experience, we can usually identify the reasons for the acoustic test failure. By analysing the test results and carefully listening for the noise paths transmitted through the dwellings, we can normally provide basic advice on the day of testing; however, on rare occasions the reasons for acoustic failure can be less obvious, and further investigative work may be required using non-destructive methods such as acoustic cameras that can accurately identify the problem with a high degree of precision.

What other services do you provide? 

Our Pre-completion testing services include:

• Acoustic design advice for party walls and floors

• Sound insulation pre-completion testing

• Air tightness testing

• Approved Document F Extract Ventilation Testing

• Thermal imaging inspections

We can also provide a wide range of energy assessment services including SAP Calculations, SBEM Calculations, EPCs. We can help with your acoustic design and sound testing.

If you are unsure about how many sound insulation tests you require, or which walls or floors require acoustic improvements to meet the requirements of Approved Document E.Contact APT Sound Testing by visiting their website or email [email protected] 

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