Sound Testing | Building Regulations Approved Document E

Sound Insulation Testing (or Sound Testing, as it’s often referred), is normally required as part of Pre-Completion Testing (PCT) when a building has been constructed or converted to create attached dwellings, flats or rooms-for-residential use.

In England and Wales, the Building Regulations Approved Document E (ADE 2003, as amended) requires that separating walls and floors must achieve minimum performance standards for airborne and impact sound insulation.

Section 5 of the Scottish Building Standards sets the performance standards and the requirements for post-completion testing in Scotland.

In England and Wales, buildings that have been purpose built have a higher performance standard when compared to those formed by material change of use (See Table 1a below). Rooms for residential purposes (e.g. hostels, hotels and student halls of residence) are also covered by the Regulations where different values may apply (see Table 1b below).

Your building control body will normally specify the units and forms of construction to be tested.

The easiest method of determining how many tests is required for your development is to start from a “set” of six tests (two airborne wall tests, two airborne and two impact floor tests) per 10 dwellings that are a “group” of the same construction.  If different constructions are used, then more tests should be undertaken.  If there are no floors in the development, then only walls can be tested.

• count the total amount of residential dwellings / flats / rooms that are separated by a common construction method
• round the amount of rooms UP to the nearest 10
• a “set” of six tests (two airborne wall tests, two airborne and two impact floor tests) are required per 10 dwellings

For other building types (e.g. schools) there will be a requirement to consider a different number of constructions and sound insulation tests across the development, where specialist advice should be sought unless a testing schedule has been pre-defined for the project.

This can be undertaken in exceptional circumstances and in agreement with your Building Control Body.  The normal requirement is to test between rooms of residential uses (e.g. bedroom to bedroom, living room to living room) and not common areas.

A minimum room volume of 25 m3 is recommended under Approved Document E.

As there is a practical lower limit that can be applied to complete a sound test in accordance with the required standards, which in turn can alter the uncertainty or reproducibility of the test.  Testing in very small rooms (such as corridors) is not recommended as it is often not possible to undertake a valid test.

Enhanced sound insulation performance standards can apply where a residential room is separated from another room of non-residential use (e.g. commercial office, bar or shop below a flat).  The minimum performance standards of the Regulations must be exceeded in England and Wales, and specialist advice should be sought on the level of sound insulation that is required.  Enhanced sound insulation requirements can also appear as part of planning conditions or project requirements (e.g. BREEAM).

It is normally the case that an additional pair of airborne sound insulation tests will be required, per construction group, where commercial units adjoin residential dwellings.

Airborne sound (sometimes termed airborne noise) is sound that is transmitted through the air; which in a residential scenario can include speech, television and radio, or dogs barking.

Airborne sound insulation tests determine the level of airborne sound insulation of a separating wall or floor.  The term used is the weighted standardised level difference D_{nT, w} and for Approved Document E this is corrected using the low-frequency C_tr weighting where the result is equal to D_{nT, w} + C_tr and expressed in decibels.

An airborne sound insulation test requires a sound source to generate high pressure levels in a source room, which is measured in the source and receiver room directly adjacent, above or below; to determine the level difference across the separating wall or floor.  The background level and reverberation time are also equated in the receive room to calculate the standardised level difference.  The test standard requires the receiver sound level to be 10 dB (i.e. subjectively twice as loud) as the background level at all frequencies under test.  This means that either very high source levels and/or low background levels are required to generate valid results.

Impact sound (sometimes termed impact noise) is mainly structure-borne sound that occurs when an object impacts on a structure; which in a residential scenario corresponds to footsteps on a floor.

Impact sound insulation tests determine the level of impact sound insulation of a separating floor.  The term used is the weighted standardised impact sound pressure level L’_{nT, w} where the result is expressed in decibels.

An impact sound insulation test requires a calibrated impact source (i.e. a tapping machine) to generate standard tapping sounds in a source room, which is measured in the receiver room directly below.  The background level and reverberation time are also equated in the receive room to calculate the standardised impact sound pressure level.  The test standard requires the receiver sound level to be 10 dB (i.e. subjectively twice as loud) as the background level at all frequencies under test.  This means that very low background levels are required to generate valid results, particularly where the impact sound insulation performance of the floor is high.

Before a sound test is completed it is vital to ensure that a space is properly prepared, as the state of the building can have a substantial impact on the results.  Here is our checklist of things to consider before the test takes place:

• Access shall be provided to all the rooms to be tested
• All site-based noise sources (radios, alarms, building work) to cease for the duration of the tests where properties will need to be vacated.
• Doors and windows (including any trickle vents) must be fitted and working correctly.
• Second-fix electrical fittings must be completely in-place and fully functional.
• 240-volt power should be provided in every room to be tested.
• Floor finishes such as carpets, laminated flooring and tiles should not be fitted on the upper floor levels for rooms to be tested for impact sound.
• Skirting boards should not touch any floating floor installed.
• All gaps in the walls and floors should be sealed.

The above points are all essential if we are to achieve reliable sound test results.  If unsuitable testing conditions are provided which cannot be easily rectified, our quoted terms of testing dictate that abortive fees can apply.

Sound testing can also apply to a range of commercial and education buildings which can be covered by our scope of accreditation.

• Offices (BS EN ISO 140-4 and BS EN ISO 140-7)
• BB93 Acoustics of Schools (BS EN ISO 16283-1* and BS EN ISO 140-7)
• DoE HTM-08-01 Acoustics (BS EN ISO 140-4 and BS EN ISO 140-7)
• BREEAM (ADE Annex B, BS EN ISO 140-4 and BS EN ISO 140-7)

*SSC is seeking to include both BB93 and ISO 16283 Parts 1 and 2 within it’s UKAS scope by July 2019.  This does not exclude SSC providing accredited measurements of schools for indoor ambient noise level, reverberation time or sound insulation under its current scope.

In the event of a failure to meet the project’s acoustic criteria, consultancy advice can be provided to achieve a suitable design standard.

Sound Solution Consultants Ltd qualify under Clause 1 of a BREEAM complaint test body, when considering relevant building acoustics measurements under our UKAS accreditation.  This typically covers measurements of sound insulation, reverberation time or ambient noise level under the standards listed for health and wellbeing (HEA credits) acoustic performance.

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The Code for Sustainable Homes was an environmental assessment method for rating and certifying the performance of new homes in the UK; encouraging sustainable home building.  It was withdrawn by Government in 2015.

Regarding health and wellbeing credits, superior levels of sound insulation were built into the Code, requiring enhanced performance standards to be met within the built development by pre-completion testing, or via Robust Details Ltd certification scheme.