Sound Testing and Noise Flanking
Part E of Building regulations require that buildings are to be sound tested prior to completion in order to confirm they meet or exceed the ISO 140-4 & 140-7 standards. The person carrying out the building work should arrange for sound insulation testing to be carried out by a test body with approved qualifications and affiliations such as a UKAS accredited company.
The test organisation should be able to schedule the tests; however this will need to be confirmed by the relevant Building Inspector. If the building fails the sound test the sound insulation will need improving and the partition re-tested. Should the building fail the sound test we can undertake a design review of the partition and make recommendations to help you pass part E.
APT Sound Testing are UKAS accredited to carry out the required sound insulation testing on new build or conversion projects and we can a very competitive price. All our engineers carry out the sound test measurements in compliance with the current British Standard: The airborne and impact sound insulation tests carried out in full accordance with the measurement procedures of BS EN ISO 140-4.
The field measurements are with a single figure DnTw and LnTw in accordance with BS EN ISO 717, the Spectrum Adaptation Ctr – which is a correction factor calculated from the measured DnT.w and the corresponding third octave band DnT values are also included within the measurement. This is applied to airborne test results and is measured in dB.
The Sound testing procedure is quite simple and our engineer will be happy to explain this on site. There are three types of sound insulation tests. For party walls there is one type of sound insulation test which is airborne sound test and for floor partitions there are two types of sound insulation tests which are airborne and impact sound insulation tests.
The airborne sound insulation test is carried out by means of a dodecahedron loudspeaker emitting a steady noise source on one side of the wall or floor partition. The corresponding sound levels are then measured on the other side of the partition. Impact sound insulation tests are carried out by means of a tapping machine placed on the floor sample to be measured and the noise measured in the room or space below.
Calculations are undertaken based on these measurements and parameters and are compared to the Building Regulations Part E sound insulation requirements for the given type of the building, i.e. a refurbished or new build project.
Flanking Noise Transmission
When attempting to make any sort of construction compliant to the Part E Regulations, it is important to note that sound does not always go straight through the building element.
To reduce the risk of this is extremely important that measures to minimise flanking sound transmission are employed at the design stage and the builder installs the specified products correctly as to manufacturer’s guidelines. If the wall or floor concerned has good sound reducing capabilities but the floor wall junctions are weak then the sound will simply escape at this weak junction.
Flanking Transmission often occurs when sound travels along elements shared by adjacent structures. If measures to tackle Flanking are not correctly specified or constructed, Flanking Transmission can often exceed the direct noise transmission through the test partition resulting in a failure even if the actual partition is capable of passing Part E.
One way of dealing with sound flanking issue is to use isolation strips around the perimeter of the partitions at the edges of floors and walls. Acoustic sealant should also be incorporated wherever possible. One of the main reasons for sound test failures due to noise flanking failures is when the inner leaf of the perimeter wall is built with light weight blocks.
This acts like a large snare drum and the sound simple travels straight up the wall from one flat to the flat above and/or below. If you have used lightweight blocks in your onsite construction and the building fails the sound test you may need to construction an independent internal plasterboard lining throughout the inner perimeter wall, this should isolate the lightweight blocks and ensure the flanking path is minimized.
If you would like more information in regards to sound testing please follow our blog at: http://soundtestinguk.blogspot.co.uk/, or visit our website at: www.aptsoundtesting.co.uk