Sound Insulation Testing Explained

One of the many Building Regulations requirements when developing residential properties is to achieve a certain standard of sound insulation performance between dwellings.

The specific performance requirements for new builds and conversions are set within Approved Document E (2003 Edition) and are summarised in the following tables.

New Builds
Airborne Sound Insulation (DnT,w + Ctr)

≥ 45 dB

Impact Sound Insulation (L’nT,W) for floors only

≤ 62 dB

Conversions

Airborne Sound Insulation (DnT,w + Ctr)

≥ 43 dB

Impact Sound Insulation (L’nT,W) for floors only

≤ 64 dB

What does all this mean?

The first step is to understand what these figures mean. First of all, these apply only to party elements, i.e. walls and floors between dwellings, not within the same flat or house.

The whole purpose of this regulation is to provide adequate sound insulation between neighbours. As shown in the tables above, the criteria for conversions is slightly more lenient than for new builds, as it is assumed that it is more difficult to implement sound proofing to existing structures as opposed to constructing from scratch.

Airborne sound insulation

Let’s now look at the airborne performance requirement, which applies both to party walls and floors. This level is, simply put, the difference between the source level and the receiver level during sound insulation tests. For example, if the source level in one flat is 100dB and the receiver level in the neighbouring flat is 45dB, the level difference (or sound reduction performance) is 55dB. This difference is then corrected for several factors such as background noise, room characteristics and frequency weighting (which we will not dwell on), giving the final sound insulation performance value of the tested element. So, the higher this number, the better the performance.

Impact sound insulation

Now, the impact insulation performance values shown only apply to party floors and related to the effectiveness of the floor construction in absorbing shock, hence not transmitting footfall noise. The measurement is done by using a tapping machine (as pictured on the top right corner of this article) which has 5 weights tapping in regular succession on the tested floor. The noise levels in the room below are then measured and averaged for different tapper positions, giving the sound reduction rating of the floor. So, in this case, the lower the figure, the better the performance.

Implications

Unfortunately for developers, both the impact and airborne insulation performance of floors are (or should be) assessed against these minimum performance requirements for new and converted developments. Tackling these two aspects involves different construction techniques and care in detailing.

If you are developing or converting a house into flats, be sure to read how to pass sound tests for floors.

These revised regulations are good news for future residents as an adequate level of soundproofing between dwellings should be demonstrated by sound testing before developments are signed off.

Posted in Building Regulations, Sound Insulation
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