Pipe down
Pipes carrying waste water should neither be seen nor heard. Des Dolan of Durapipe looks at the issue of noise attenuation and how it can be achieved effectively.
As the design and construction of modern buildings has become more sophisticated, acoustic performance has become an increasingly important issue. For example, the noise generated from floors is much more noticeable in contemporary buildings, as the traditional sound absorbing carpet is often being replaced by the more ‘fashionable’ hard floorings of laminate, tile and marble.
However, it is not just noise from floors and stairs that disturbs consumers. The sound of a flushing toilet or running water can cause just as much noise pollution for visitors or occupiers of a public building and needs to be carefully considered at the outset of a project.
Minimising the sound emitted by sanitary installations is crucial within modern buildings and particularly multi-occupancy developments such as apartments, hotels and leisure venues.
Noise control in buildings in England and Wales is regulated using Building Regulations Approved Document E. The aim of this regulation is to protect residents and users of a building from the noise of activities in other rooms or adjoining properties.
The guidelines in this document apply to any building used as a dwelling — including houses and apartments and rooms for residential purposes, such as student and nurse accommodation, nursing homes and hotels.
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Designed for low-noise performance — Durapipe’s acoustic drainage system.
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Building Regulations, Part E, provides a minimum sound-level requirement for the noise generated from floors, walls and stairs, which covers both airborne sound and impact sound. Unfortunately, Approved Document E does not give a performance standard for drainage systems. However, while there are no minimum sound levels stipulated, the regulations do state that pipework used within plumbing and drainage systems should be enclosed and recommends it is lagged with 25 mm of unfaced mineral fibre.
Traditionally, plastic pipework is lagged with mineral wool and installed within a duct wall to achieve the guidelines set out in Building Regulations, Part E. However, this can be a timely and costly exercise for contractors, who often do not realise there are more cost-effective options available.
New independent research conducted by the Fraunhofer Institute of Building Physics (IBP) in Stuttgart has measured the noise generated from both lagged and unlagged plastic pipework systems used for sanitary drainage systems. The findings reveal that it is possible to meet the Building Regulations without the need to lag pipework, providing contractors with a solution that offers improved performance, while significantly reducing labour time and costs.
The system tested was Friaphon — a purpose-designed sound-reducing drainage system that offers outstanding sound insulation properties compared with traditional cast-iron or lagged single-wall plastic drainage systems.
The IBP undertook ‘laboratory measurement of noise generated from waste water installations’ in accordance with BSEN14366. The Friaphon sound-attenuated drainage system and a lagged single-wall PVC pipework system were tested following the same process.
A Friaphon downpipe was installed leading from the top floor of a 3-storey building to the sub-basement and fastened to the installation wall using Friaphon rubber-lined support clips. In the basement, two 45° bends changed the pipe run from vertical to horizontal. A water inlet pipe was connected on the top floor level and water introduced according to the standard BS EN 14366.
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| Table 1. Independent tests of Durapipe’s sound-attenuated drainage system show a better acoustic performance than lagged PVC, and at a lower installed cost. |
As the noise generated in a waste-water system depends on the flow rate, noise measurements were performed four typical flow rates (0.5, 1.0, 2.0 and 4.0 l/s). A flow rate of 2 l/s roughly corresponds to the average required for flushing a toilet. Noise measurements were then taken in the room behind the installation wall.
The above procedure was then repeated for a single-wall PVC soil pipe, fastened to the wall using standard pipe clips and lagged with 25 mm of unfaced mineral wool, as recommended in Building Regulations, Part E.
The test results demonstrated that Friaphon generated less noise than the PVC pipe lagged with traditional mineral wool, and therefore better performance capability (Table 1). Sound levels below 10 dB(A) in the table are subject to increased measurement uncertainty and, moreover, are not noticeable in a normal living environment.
With acoustic performance becoming ever more important to contractors, consultants and end clients, continued technical advancements have meant that various pipework systems are now promoted as being specifically engineered to meet and address acoustic requirements.
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| Not only does Durapipe’s Friaphon acoustic drainage system have competitive materials costs, but it also has lower installed costs than other drainage systems. Lagging costs of other systems, where required, are based on £15 per metre. |
Our advice, however, is that not all products will perform to the standards set out in the Building Regulations, so contractors need to be asking to see performance testing data to be certain of the product claims.
Cost is always a major consideration when looking at specific sound-attenuating products. With high-performance plastic brands it is possible to install a cost-effective solution with outstanding sound-insulation properties. In addition to its excellent acoustic performance, compared with traditional cast-iron or lagged single-wall plastic drainage systems, Friaphon also offers significant installed-cost savings as it does not need to be lagged, cutting out the labour time and cost associated with this process.
With budgets becoming ever stricter and project timelines shrinking, contractors need to be demonstrating that they can deliver the most cost-effective solution for sound insulation. Those that can show a way to achieve the same, if not better, acoustic performance as traditional materials, while reducing installed and life-cycle costs, will win tenders over their competitors.
Des Dolan is building-services brand manager for Durapipe UK.
