Sound Testing | Building Regulations Approved Document E

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).

These values are proven in the field, following Building Regulations sound testing procedures (Annex B).

Your building control body will normally confirm the forms of construction to be tested, under pre-completion sound testing.

The easiest method of determining how many soujd insulation tests are 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 sound tests should be undertaken.  If there are no floors in the development, then only walls can be sound 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
• Repeat for each construction variation used

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

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

A minimum room volume of 25 m3 is recommended in the sound testing procedure, from Annex B of Building Regulation Approved Document E.

There is a practical lower room volume limit to any room, that can be applied to complete a valid sound test in accordance with the required acoustic testing standards. In turn, a small room size can alter the uncertainty or reproducibility of the test.  Sound testing in very small rooms (such as corridors) is not recommended as it is often not possible to undertake a valid test within the constraints of the space and is otherwise not advocated under Building Regulations Part E.

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 Building Regulations Approved Document E 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 where commercial units adjoin residential dwellings.  Additional Building Regulations sound testing is likely to be required if different construction groups exist to commercial areas (e.g. walls and floors, or two types of floor).

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. This is commonly referred to as how “soundproof” a residential wall or floor is, where Building Regulations Approved Document E provides a method for “sound proof testing” these structures, using high noise levels.  These “noise tests” provide airborne sound insulation values that are compared against Building Regulations sound testing performance standards.

The term used for airborne acoustic tests is the weighted standardised level difference D_{nT, w} and in Building Regulations sound testing 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. The exacting method is described within pre-completion sound testing, under Annex B of Building Regulations Approved Document E.

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.  This is commonly referred to as how “soundproof” a residential floor is from footsteps, where Building Regulations Approved Document E provides a method for “sound proof testing” these structures, using a tapping machine.  These “noise tests” provide impact sound insulation values that are compared against Building Regulations sound testing performance standards.

The term used is the weighted standardised impact sound pressure level L’_{nT, w} where the result is expressed in decibels. The exacting method is described within pre-completion sound testing, under Annex B of Building Regulations Approved Document E.

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 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:

• Safe access and keys will be provided to all rooms to be tested, on all levels of the building. Note that our staff are not permitted to use temporary stairs, ladders or scaffolding to move between test rooms whilst carrying associated testing equipment
• All properties will be fully vacated during the entire duration of the test. The visiting engineer will notify the site manager if anyone needs to be removed from test rooms
• The type of room to be tested should be a living room or bedroom
• Volumes ≥ 25 m³ on both sides of the separating element to be tested
• All floor and ceiling surfaces are complete and free of debris or furniture
• All cornices and skirting boards should be in place
• 240 V (mains) electrical outlets available in all rooms to be tested
• All electrical and other sockets on the separating element shall be fitted
• All doors and windows of the rooms under test shall be fitted and working correctly; to permit them fully closed and sealed, as appropriate
• Window trickle vents to be fitted and closed (or the openings temporarily blocked up) for all rooms to be tested
• All site staff shall be made aware of the requirement to limit background noise during the sound tests, as this can affect the quality or validity of the results obtained
• Any ‘noisy’ building work in the vicinity of the test rooms will be stopped during the entire duration of the test. This includes noise sources (e.g. radios) turned off and external ground works, painting or cleaning activities halted about the test rooms
• Noisy (i.e. beeping) smoke alarms must be de-activated prior to testing
• Noisy ventilation systems in rooms must be turned off prior to testing
• Floor finishes (such as carpets, vinyl, ceramic tiling or timber laminates) have not been fitted in rooms if separating floors are to be tested

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.