Approved Document E (ADE) of the Building Regulations was revised in 2003. The new document requires pre-completion tests (PCTs) in all developments including new build and converted houses, flats, hotels and hostels.

The only alternative to PCT is to register and build a ‘Robust Detail'. This is a form of construction which has been ‘site-proofed' by targeting a higher performance standard, and allowing only well controlled construction methods and materials.

For all development with party walls or floors which are not part of the Robust Details scheme, a sample of 10% of the properties in each development should be tested, but this is to be sub-grouped according to construction type. 10% of each type of dwelling on each site should be tested to demonstrate compliance, or otherwise, to Building Control.

The exact requirements for testing on each site will be at the discretion of Building Control, who will be expected to select which plots are to be tested. In reality this is likely to result in more than 10% testing, as many sites comprise less than 10 houses.

The new ADE states that tests should be carried out by independently accredited organisations. There are two forms of accreditation available for these tests via the UK accreditation service (UKAS) and the Association of Noise Consultants (ANC) registration scheme.

ASA has been extensively involved in the ANC Registration scheme, which is intended to provide the required level of confidence in tests carried out by suitably qualified and experienced staff, which accord with the appropriate standards and are properly traceable and audited. The tests will include a clear PASS/FAIL statement for each partition, and a certificate which is easily recognised for approval by building control.

Frequently Asked Questions

Q How are the tests done ?

A In very simplistic terms, a known steady source of noise is generated on one side of the wall or floor, and the amount transmitted to the neighbouring room is measured to determine how much noise the wall or floor is cutting out. For impact tests, a special ‘tapping machine' is set running on the upstairs floor, which applies a known force to excite the structure. The noise level in the room below is then measured and rated to determine how effective the floor would be at reducing footfall noise transmission.

To go into a little more detail, the less patient may wish to skip this bit;

A pseudo-random pink noise source is used, with suitable amplification equipment, to generate high levels of noise as a reverberant field in the ‘source' room. Source and receive room measurements are carried out, generally with a type 1 real time analyser, in 1/3 octave bands, with background levels and impact receive room levels measured in the same way. Reverberation times are also measured in the receive room. Level differences (or just levels for impact) are corrected for background noise and standarised for the reverberant conditions of the receive room. These corrected level differences are rated against a standard curve, fitted using summed adverse deviations to establish D nTw . Spectral adaptation terms are then applied to provide greater low frequency emphasis, and the result published as a D nTw +C tr single figure value. Well, you did ask….

Q What is a ‘set' of tests ?

A This depends on the type of dwelling. If there are both party walls and floors, a ‘set' would involve six separate tests to establish the airborne wall performance between two pairs of rooms and both airborne and impact performance of the floors between two pairs of rooms. Again, the selection of rooms to test would be at the discretion of Building Control.

Q How much will the tests cost ?

A Each testing contractor will agree a fee with their client (the builder) which will depend on the specifics of the site in question, and the number of tests they are able to carry out in one visit. The regulatory impact assessment of the revised document contained an estimated range of £200-£650 for each pair of walls and £550-£1500 for each pair of floors.

At ASA we have set a pricing structure which includes a fixed fee for the first test, and then a greatly reduced fee for every subsequent test we carry out during the same visit. Generally two engineers would be involved, and they would be instructed to test as many of the requested adjacencies as they can. For specific quotations please contact us directly.

Further details of the Robust Details scheme can be found at www.robustdetails.com .