Sound Insulation Testing | Building Regulations Approved Document E

Your building control body will normally confirm the forms of construction to be tested.

When determining the number of tests that are required for your development. The easiest method is to start from a “set” of six tests (two airborne wall tests, two airborne and two impact floor tests). This would be 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.
• Repeat for each construction variation used

For other building types such as schools. The number of tests will differ from the above. As you will need to consider the whole development. Specialist advice should be sought. Unless a testing schedule has been pre-defined for the project by an 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 tests between rooms of residential uses. For example, bedroom to bedroom, living room to living room. Not to-or-from common areas.

A minimum room volume of 25 m3 is recommended. See Annex B of Building Regulation Approved Document E.

There is a practical lower room volume limit to any room. Which can be applied to complete a valid sound test in accordance with the standards. In turn, a small room size 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 within the constraints of the space.  It is also not advocated under Building Regulations Part E.

Airborne sound is sound that is transmitted through the air. So, in a residential scenario can include speech, television and radio, or dogs barking.

To determine how airborne sound insulated a wall or floor is (or how soundproof they are). Building Regulations Approved Document E provides a method for testing these structures, using high noise levels.  These tests provide airborne sound insulation values. That are used to compared against Building Regulations performance standards.

The 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. This will determine the level difference across the separating wall or floor.  The background level and reverberation time are also equated in the receive room. We do this 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.

The term used for airborne sound tests is the weighted standardised level difference D_{nT, w} . In Building Regulations, 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 exact method is described under Annex B of Building Regulations Approved Document E.

Impact sound is mainly structure-borne sound that occurs when an object impacts on a structure. So, in a residential scenario this corresponds to footsteps on a floor.

To determine how impact sound insulated a separating floor is (or how soundproof a floor is). Building Regulations Approved Document E provides a method for testing these structures, using a tapping machine.  These tests provide impact sound insulation values. That are used to compared against Building Regulations performance standards.

The test requires a calibrated impact source, such as a tapping machine. To generate standard tapping sounds in a source room. This is then measured in the receiver room directly below.  The background level and reverberation time are also equated in the receiver room. We use this 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.

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 under Annex B of Building Regulations Approved Document E.

Before a sound test is completed it is vital to ensure that space is properly prepared. 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 m³on 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, working correctly (fully closable) and sealed.
• Window trickle vents to be fitted and closed (or the openings temporarily blocked up). This is required for all rooms that are being tested.
• All site staff shall be made aware of the requirement to limit background noise during the test. 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.

The Code for Sustainable Homes was an environmental assessment method for rating and certifying the performance of new homes in the UK. It encourages 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. These require enhanced performance standards to be met within the built development by pre-completion testing. Or via Robust Details Ltd certification scheme.