Frequently Asked Questions

It is important to be clear as to the precise acoustic compliance criteria for your project, both when designing as well as assessing at pre-completion stage.

This depends on the type of development. Below is a list of typical standards:

Residential: Approved Document E, Code for Sustainable Homes.

Schools: BB93, BREEAM Education 2008 / 2011

Colleges & University: BREEAM Education 2008 / 2011

Hospitals: HTM 08-01, BREEAM Healthcare 2008 / 2011

Offices: BS 8233:1999, BREEAM Offices 2008 / 2011

In addition to the above, there may also be employer’s requirements or acoustic related planning conditions applicable to the project.

Again, this would depend on the type of development. For new build residential developments, or those formed by material change of use, pre-completion sound insulation testing is mandatory for compliance with Approved Document E, unless the scheme is registered with Robust details. For school, hospital and office developments, testing may not be mandatory, however, it is likely to form part of the employer’s requirements, particularly where the project is BREEAM registered.

This depends on the type of development. Typically, acoustic testing could include the following:

• Measurements of sound insulation, e.g. between dwellings or between classrooms – both airborne and impact.
• Internal ambient noise monitoring.
• Measurements of mechanical services noise – both internal and external.
• Reverberation time measurements.

Sound insulation testing is an assessment of the amount of noise reduction between adjacent dwellings / classrooms / hotel rooms etc. There are two types of test which can be carried out, those which measure airborne sound insulation & those which measure impact sound insulation (floors only).

Airborne sound insulation testing involves placing a loudspeaker to one side of the separating wall or floor and measuring the sound level in the room the other side of the separating wall or floor to determine the level of noise reduction. Impact sound insulation testing involves placing a standardised tapping machine onto the floor of the source (upper) room and measuring the sound level in the receiving room below.

This involves generating short bursts of sound, either from a loudspeaker, or, for example, by popping a balloon, and then measuring the time taken for the sound level to decay by a specified amount.

Testing is normally undertaken when properties are finished but unfurnished. This normally equates to all windows and doors fitted and sealed, all sockets fitted, ceilings installed etc. It may be necessary to carry out impact testing before carpets are fitted.

This depends on the type of testing being carried out. For sound insulation testing, 240V power within the rooms to be tested is preferable for accuracy of testing, although 110V power can also be used. Due to the high noise levels generated during sound insulation testing, no other site personnel are allowed in the rooms in which the testing is taking place. Any particularly noisy activities may need to be suspended.

For internal ambient noise monitoring or mechanical services noise measurements, all site activities may need to be stopped for the duration of the measurements so that the accuracy of the measurements is not compromised by construction activity noise not normally present.

If unsure contact HRS to confirm requirements.

DnT,w is an on-site measured performance parameter. It is the actual level of sound insulation achieved between two adjacent spaces. Rw describes the sound transmitted through a single element, such as a wall, door or window. It is measured in a laboratory. The DnT,w of a separating wall or floor will typically be around 5 to 7 dB lower than the specified Rw for the single element, due to flanking sound transmission around the element.

When a noisy activity, such an industrial or commercial development, is introduced into a noise sensitive area, it will often be necessary to carry out a noise impact assessment, e.g. for BREEAM credits or for compliance with a planning condition.

A noise impact assessment is most commonly required for noise from mechanical services equipment, such as condensers, chillers and air handling unit. BS 4142:1997 is typically used to assess whether noise from such sources is likely to give rise to complaints from people residing in nearby noise sensitive premises, e.g. dwellings, schools, hospitals, churches etc.

The assessment process first requires that the existing background noise levels outside the nearby noise sensitive properties be established. Using manufacturer’s data the noise level due to the new plant items outside the noise sensitive properties is calculated and compared to the existing background noise levels to determine the likelihood of complaints. It may be necessary to take measurements of the new plant items once they become operational to confirm noise levels.

Noise impact assessments may also be required, for example, for delivery noise associated with a new retail development or noise resulting from a new entertainment venue.