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Pre-Completion Testing

Pre-Completion Testing

Pre-Completion Testing

With higher density developments and changing population demographics, sound transmission between buildings is an increasing problem. The revised Sound Resistance Regulations (Pre-Completion Testing Regs) have been designed to counter the rising level of complaints received about noise transmission and improve the welfare and convenience of building users.

What types of tests need to be done?

There are two types of sound test – airborne and impact. Airborne tests are carried out on walls and floors separating dwellings, impact tests are carried out on floors separating dwellings.

How many pre-completion tests do I need to have?

For every 10 dwellings within a property 1 complete dwelling will need to be tested. The number of tests within that dwelling will depend on the number of walls or floors between adjoining dwellings. If multiple wall or floor constructions are used – tests will need to be carried out on each type of construction. A typical flat in a large block will require 6 separate tests – 2 impact tests (1 in the bedroom and 1 in the living room), 2 vertical airborne tests across the separating floor and 2 horizontal airborne tests across the separating walls. A terraced house will only require 2 airborne tests across the separating wall.

But what if I’m developing only two attached dwellings?

The number of dwellings that require testing is obtained by dividing the number of adjacent dwellings by 10 then rounding up to the nearest 1, so for 2 dwellings – 2/10 = 0.2 = 1. Therefore 1 dwelling would require testing. Which rooms within each dwelling will be tested?

Pre-completion testing is conducted between key living spaces where possible. Key living spaces are bedrooms and living rooms. Testing is not carried out between living spaces and corridors/stairwells. Generally, the Building Control Officer will nominate the partitions that he/she wants to be tested. How are the pre-completion tests performed?

  1. Airborne tests are conducted using loudspeakers and a sound level meter. The loudspeakers are used to produce noise in one room (source) which is then measured in the room on the other side of any separating partition between dwellings (receiver). Using additional acoustic measurements inside the receiver room, the difference between the noise levels in each room can then be calculated to give the sound reduction of the separating partition.
  2. Impact tests are only performed on floors between adjoining dwellings. The test is performed using a standard “tapping” machine and a sound level meter. The tapping machine is a device that ‘taps’ on the floor emulating the sound of people walking around or other objects ‘impacting’ with the floor. The machine is turned on in the source room and measurements are taken in the receiver room. Using additional acoustic measurements inside the receiver room, a value for the impact sound can then be calculated.

What are the requirements of Pre-completion testing?

See the tables below.

What does DnT,w+Ctr mean?
DnT,w+Ctr is a expression of the acoustic insulation of a partition. The higher the value, the better the partition performs. The expression takes into account background noise levels and reverberation times in the receiver room and is the current standard for measuring sound reduction between walls.
What does LnT,w mean?
LnT,w is the weighted standardised impact sound pressure level and is used to express the amount of noise present in the receiver room. A high LnT,w value represents poor performance of the separating partition. LnT,w incorporates receiver room acoustics into its calculation and is the current standard measurement for impact noise.
What happens if a partition within my development does not meet the requirements?
In the event of a test not meeting the requirements of Part E, the developer will be required to perform remedial works to the relevant construction and all similar constructions. Further pre-completion testing of the treated constructions will then be required to demonstrate that Part E requirements have ultimately been met. Normally, Building Control will require an increased percentage of dwellings to be tested following a failed test.
I have used Robust details, do I need pre-completion testing?
If you have registered the constructions with Robust Details Ltd then pre-completion testing is not required. If you have followed the robust detail guidance but have not registered the constructions then pre-completion testing will be required.
What are Robust Details?
Robust details are wall and floor constructions that are expected to achieve part E requirements and therefore do not require testing. As mentioned above these need to be registered to avoid pre-completion testing.
When should pre-completion testing be carried out?
Pre-completion testing should be carried out when the building is complete but not furnished. All floors and walls should be finished and sealed but second fixings are not essential. Carpets should not be laid with the exception of those floors where the carpet is an integral part of the floor (i.e. Floor type 1 in Approved Document E – “Concrete base with ceiling and soft floor covering”).
What conditions are needed on site?
  1. Quiet conditions are preferred so that tests can be carried out efficiently. However with the appropriate testing equipment and procedures, a degree of noise on site can be worked around, thus minimising site downtime.
  2. A 240V supply should ideally be available, either within the property or via an extension. Otherwise a silenced generator is required
  3. Access to the rooms both side of a partition is required.

Part ‘E’ Performance Requirements – England & Wales

Table 3.1 Dwelling Houses and Flats – Performance Standards for separating walls, floors and stairs that have a separating function
Value in dB
Purpose Built Dwellings Dwellings formed by material change of use
Walls DnT,w + Ctr (airborne) 45 dB 43 dB
Floors DnT,w + Ctr (airborne) 45 dB 43 dB
Floors DnT,w + Ctr (airborne) 62 dB 64 dB
Table 3.2 Rooms for Residential Purposes – Performance Standards for separating walls, floors and stairs that have a separating function.
Value in dB
Purpose Built Dwellings Dwellings formed by material change of use
Walls DnT,w + Ctr (airborne) 45 dB 43 dB
Floors DnT,w + Ctr (airborne) 45 dB 43 dB
L’nT,w (impact) 62 dB 64 dB
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