Noise reduction for soil and waste systems

In this post, we look at the issue of noise in soil and waste systems including what causes it, how to use Fraunhofer IBP reports and how to reduce noise.

The issue of noise

The World Health Organisation, describes noise pollution as noise is one of the top environmental hazards to both physical and mental health and well-being in the European Region stating that excessive noise can seriously harms human health and interferes with people’s daily activities at school, at work, at home and during leisure time. It can disturb sleep, cause cardiovascular and psychophysiological effects, reduce performance and provoke annoyance responses and changes in social behaviour. The effect of noise is subjective so can vary for different individuals but for some a persistent drip of a tap for example can have a greater impact than very loud music. Noisy pipework can be irritating for occupants of building especially as it can occur at any time of day or night. Part E of the Building Regulations (2010) aims to minimise this by stating that sanitary noise in new and refurbished residential properties should not exceed 45 dB as a daytime average.

What causes noisy pipework?

Noise in pipe work is created by water and air passing each other, waste water changing direction at branch pipes and in bends, or passing a reduction , water falling through a vertical soil and waste pipe and hitting a solid surface such as the bend at the bottom.  It can then travel through water and pipe walls or radiate from soil and waste pipes. It can also travel via pipe support to building constructions.

  • soil pipe noise
    Example of noise radiation from flanking building constructions
noise in pipework
Examples of where noise can occur

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 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 a 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 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.

Fraunhofer IBP test environment
Fraunhofer IBP test environment

Use the sound check tool

sound check tool

 

Use our free tool to calculate noise reduction of Wavin AS+ for your building project. Find the Wavin SoundCheckTool here.

Reducing noise

Noise reduction can be achieved by careful planning and installation as well as choice of product.

  • Reduce the water flow rate if possible
  • Reduce water speed as much as possible
  • Use soft direction changes, e.g. 2 x 45° bends, instead of 1 x 88.5° bend
  • A 250mm pipe should be installed between two 45° bends when space permits in buildings with more than three storeys
  • Use pipe supports with rubber inlays (reduce noise by up to 3dB(A)) • Mount pipe supports on the heaviest wall, which is most resistant to vibration
  • Use the lowest possible number of pipe supports to limit transfer of noise to the wall. However, the max. distance between supports must be observed
  • Avoid fixed connections between pipe and floor slabs as much as possible
  • Separate pipes from building elements, e.g. by wrapping two or three layers of needle felt or fibre sheeting around the pipe.
  • Noise in shafts increases by 10dB(A) due to reflection from the shaft. By insulating two of the shaft sides with 30 mm mineral wool, improved absorption will prevent this.

IMPORTANT! Noise and insulation are a complex affair. If in doubt whether reduction is sufficient, contact our Technical Support Department for advice. You can also talk to a consulting engineer, or acoustics expert.

shaft insulation
Shaft insulation

Wavin AS+

Wavin AS+ low-noise soil and waste pipe system

No need to worry about adhering to noise regulations with Wavin AS+. Our premium low-noise soil and waste pipe system ticks all the boxes of noise reduction, fire safety and cost-effectiveness. Download the Wavin AS+ BIM package and start designing now!