Fraunhofer IBP reports
Most soil and waste pipes will have been tested to provide noise data in impartial test laboratories and in many cases, this will be the Fraunhofer IBP Institute in Germany.
A Fraunhofer IBP report will provide noise test results for both structure-borne and airborne sounds and will also test different flow rates in the pipes. The figures normally used are for a noise measurement taken at a flow rate of two litres, which is the amount of water passing through the pipe from a standard toilet flush. A Fraunhofer IBP report also shows the test construction in detail. For instance, it states which pipe supports and wall thicknesses are used, and describes the standards the test conforms to. Soil and waste pipes are installed in the Fraunhofer IBP test environment on a 115mm plastered concrete wall with a density of 220kg/m2, and a floor or reinforced concrete with a density of 440kg/m2. The rooms are empty and closed.
When choosing low noise and soil and waste pipes, it is important to ensure the correct data is being used. Whilst many will just use the lowest value which will be for the structure-borne result, this doesn’t represent the structure-borne sound in any building and may differ depending on the choice of materials. In particular, the following will influence how much noise from the pipe is reduced:
- The pipe supports, wall brackets and wall materials. Structure-borne sound can only be used in those rooms where it permeates through the building construction, and not on the actual installation side of the pipes.
- The materials that the pipes are installed in. Unless they are the same as the materials in Fraunhofer IBP’s test facility, then the data will not be representative.
Airborne is a much more reliable figure and so can be used on the installation site. The noise that the pipe emits itself will be the same, regardless of how it is installed. But you can only use airborne sound on the installation site if the pipe runs in a shaft, or is enclosed in some other way. However, if it is not, you can calculate how and with what you can encapsulate it to meet the building rule requirements.
The risk of simply accepting test results is that a test performed at an inspection may result in you being required to replace the pipes or provide additional noise insulation around them – which takes time and money. Using airborne sound from the pipe as a benchmark means that the reduction value for the building materials is deducted if, for instance, the pipe is installed behind plasterboard, a wall or a ceiling. The result is the level of noise the pipe will emit in a room on the installation site.