Sound Testing also known as Sound Insulation Testing is separated into Airborne Sound Transmission and Impact Sound Transmission. Approved Document E of the Building regulations references ISO 140:1998 Standards (Parts 4 and 7) as the methodology for conducting a Sound Test. Approved Document E has been adopted for England and Wales. Approved Document E requires random sampling of each floor and wall type.

Separating walls between new homes and purpose-built rooms for residential purposes must meet a minimum airborne sound insulation level of 45 dB DnT,w + Ctr (or 56 dB DnT,w in Scotland). This refers to on-site test results rather than laboratory and is quite different to internal walls. The maximum impact sound transmission level is LnT,w 62 dB (LnT,w 56 dB In Scotland) for separating floors between new homes and purpose-built rooms for residential purposes. Typically, it is accepted that in a

building comprising 1-10 units, one full set of six tests is required, 2-20 units two full sets, 3-30 units three full sets and so on. However, your building control officer might stipulate a different percentage. If there are more than 1 construction type and/or differing wall or floor types, then it is likely that a greater number of tests will be required.

Using the procedures of BS EN ISO717-1: 2013 Acoustics. Rating of sound insulation in buildings and building elements. Airborne sound insulation, the measurements is compared to a reference curve. The reference curve is shifted in 1 dB steps to determine a single figure number at 500 Hz. The single figure number at 500 Hz is then be used to Table 0.1a of Approved Document E to determine whether the wall meets the criteria for airborne sound in a new build property. Methodology was taken from BS EN ISO 3382-2:2008 section 5.2 (Interruption Noise Method) T20 rev times for the receiver room.

Using the procedures of BS EN ISO717-2: 2013 Acoustics. Rating of sound insulation in buildings and building elements. Impact sound insulation, the measurements is compared to a reference curve. The reference curve is shifted in 1 dB steps to determine a single figure number at 500 Hz. The single figure number at 500 Hz is then be used to Table 0.1a of Approved Document E to determine whether the floor meets the criteria for impact sound in a new build property.

From a developer’s perspective a new build property requires a party floor or wall to attain higher standards than a conversion. In comparison to Europe the levels required by Approved Document E remain lower than most other countries. The importance of attaining high standards of sound insulation are noted from research showing that the main causes of noise nuisance reports to local authorities in England and Wales are in relation to poor sound insulation between properties. When a noise nuisance is reported it is not uncommon for sound insulation to be retested and the quality of the build put under the microscope with potential action against the developer.

As a practice which undertakes acoustic design specifications and sound testing, we have been instructed on numerous cases when buildings have failed sound testing. It is not uncommon for new build houses and new build flats to fail sound testing. When this happens, it can be catastrophic for a developer as under Approved Document E (paragraphs 1.30 to 1.40 on page 18 of the standard) the entire building requires upgrade for the wall or floor with the same structure. Failures can occur for many reasons as shown in the following table:

The process of analysing a failed sound test is often highly technical and requires expert Building Acoustic training from an Acoustic Consultant to resolve the issue. We have noted in the past developer’s spending time and money in adding layers of expensive material with little to no improvement. Further sound tests are also being conducted without an Acoustic Consultant reviewing the plans and specification which again add further expense to the developer with little positive results.

A common response received from developers when a sound test has failed is that they the walls and floors have been constructed using an acoustic specification from an internet site. In certain cases, a specification may meet the requirements of Approved Document E when built however in several cases when combined with alternative materials or wall specifications the performance reduces significantly. The use of Robust Details is often a better route for developers who wish to use standard construction specifications however understanding of connections to walls and floors is paramount in these situations. We always suggest the inclusion of an Acoustic Consultant with a specialist interest in Building Acoustics at the planning stages in tandem with an architect.

As a case example we noted several issues on a block of New Build Flats in London which led to failures in meeting the requirements of Approved Document E. When investigated the development, despite 6 sound tests with a separate company and multiple remedial solutions including installing resilient layers, failed to influence the sound testing result significantly. On inspection it was noted that internal pillars and the construction of the walls created a significant flanking path. The development required significant structural alteration to meet the requirements of Approved Document E. This was a significant setback to the developer who had already sold the new apartments and was awaiting release of funding and certification to complete on the sale. Although this situation is not a common occurrence it identifies that when planning a new development adequate planning resource needs to be attributed to the acoustic specifications to avoid future issues and a significant impact on timeframes and finances.

Compliance 4 Buildings are available to discuss new developments of houses and flats at all stages. Our ethos at Compliance 4 Buildings is always to attain the required levels as dictated by Approved Document E in an efficient manner to reduce the chances of failure for a developer. To contact Compliance 4 Building for advice, instruction and sound testing please call 0203 556 2407 or email info@compliance4buildings.co.uk