Building Control and Acoustic Testing

For those brave people who decide to build or renovate their own properties, policy adds yet another layer of complexity to the process. Approved Document E of building regulations stipulates that all domestic buildings built without robust details are sound tested. In this article, we discuss the deal between building control and acoustic testing.

If you have questions like “how do I pass a sound test?”, “what exactly does Approve Document E stipulate?”, or “where can I book a sound test?”, then we have got the answers you’re looking for.

Approved Document E

Approved Document E of Building Regulations dictates the levels of sound reduction for all domestic developments. Approved Document E was introduce in 2003 in England, Wales and Northern Ireland. You can read the full document here. These stipulations are designed to protect residents from noise between dwellings. The regulations apply to all new-build constructions with residences next to one another, and for conversions from a single dwelling to multiple. Only under certain circumstances, these may not apply such as those around Grade Listed Buildings (these are best discussed with your Building Control Officer).

Approved Document E requires residential developments to demonstrate levels of noise attenuation performance that comply with Building Regulations. Acoustic testing assesses if your development provides insulation to adequately resist the passage of sound. This includes both airborne (noise transmitted through the air) and impact noise (noise resulting from an impact on the structure).

The two types of sound test

There are two different sound tests that could be carried out on your property: airborne and impact sound tests. A new build property without robust details will either require an airborne sound test or an airborne and impact sound test. This will depend on the type of build and its location. Get in touch with us to find out more.

Airborne tests are carried out on all separating walls between habitable rooms of flats and houses. For example, airborne sound across a lightweight floor would pass through the plasterboard ceiling, into the floor void, through the floorboards and into the room.  Its noise sources are things such as speech, music, television sound – any noise source that radiates into the air, rather than directly into the structure.

Whereas impact noise is generated by impact on the structure itself. Impact tests are typically only assessed for intermediate floors to consider noise from sources such as footsteps or chair scrapes.

What happens during an airborne test

When our acoustic engineer arrives on site, they will begin the airborne test by placing the loudspeaker in the source room.

While wearing high tech hearing protection, our engineer plays white or pink noise at a very high amplitude, to tune of 95-110 dB(A). It is imperative that no one, other than the engineer, is near the plot while testing takes place. This is because hearing protection must be worn at all times.

After taking a series of measurements with their sound level meter, our engineer will then move to the room adjacent – known as the ‘receiver room’. With the loudspeaker still on in the source room, they take another series of measurements in here.

After turning the loudspeaker off, our engineer will carry out a further two tests: one to measure the reverberation time (nT), and the other to measure background noise.

Putting these all together: the measurements of level difference, reverberation time, and background noise, enables us to calculate the DnT,w + Ctr result.

What happens during an impact test

To conduct an impact test, our acoustic engineer uses a tapping machine. The L’nT,w is determined from measuring sound levels within a room where the floor above is being excited by an impact. Our engineer uses the tapping machine to do this, which drops a series of weights/hammers on the floor in regular succession at a fixed force.

Our engineer places the tapping machine on the floor of the source room and then move down to the receiver room.

Here, the engineer takes similar measurements to those taken in an airborne test. This includes a reverberation time and background noise measurement.

Putting all these together gives us the L’nT,W result.

What Sound Insulation targets do I need to achieve?

Below we have outlined the relevant requirements in Approved Document E. The criteria for refurbishments are slightly more lenient than for new builds because it is often more difficult to soundproof an existing structure. Your Local Planning Authority will have more input when it comes suitable targets for internal noise levels. This is because standards for noise ingress (from the outside, like traffic) are not covered by Building Regulations or Approved Document E.


Am I ready for a sound test?

Building Regulations asks that dwellings built without robust details are sound tested before completion. Such buildings need to be registered with a valid certificate to be exempt from sound testing. There are certain minimum requirements in the progress of development that will impact our ability to perform acoustic testing and the likelihood of your development passing. We have compiled a checklist of items you will need to complete before you acoustic appointment.

All of our sound tests are carried out in accordance with ISO 140-4 and ISO 140-7.


Get in touch to find out more and book your sound test today.