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Building Products January 2018

INSULATION AND ACOUSTICS JANUARY 2018 | BUILDING PRODUCTS 47 measurement of noise from waste water installations, is designed to provide standardised installation by comparing different pipe systems. It specifies methods for the measurement of airborne and structure-borne sound produced in waste water and rainwater installations under laboratory conditions and defines the expression of the results. The results it produces can be used to compare different products and materials. However, although it may serve to estimate the behaviour of waste water systems in a building under certain conditions, it doesn’t provide a normalised procedure for calculating the acoustic properties of such installations in a building. On top of this, it is applicable to waste water piping systems, but crucially, not to the actual sources of the waste water (such as WCs, basins and bathtubs). A holistic approach to the entire system is needed to limit pipe noise. That’s why effective pipe system design is one of the best ways to minimise water noise. So, for example the design should: • Avoid significant changes in direction in pipes where possible – the force of water at each bend or offset creates a potential source of noise and that’s why shallow bends should be used wherever possible. • Employ sound reducing measures – these might include brackets with a rubber inlay; low-noise pipe branches, spigots, couplers or reducers; or insulated pipe clamps. • Use specialist pipework such as the TriPlus lownoise push-fit waste pipe that we supply in various sizes. • Select quiet sanitary ware with appropriate wastes and traps. It might, for example, make sense to eliminate the pedestal for a wash hand basin and instead use a wall-hung option to stop vibration through the floor. Ideally, bathrooms should produce no more than 40dB, but poor design or positioning can lead to bathrooms generating more than 50dB, too loud for most people. Bathroom noise is caused by a number of factors, including water flow through pipes and in the soil stack, as well as bathroom fittings such as showers, cisterns and basins. This noise can be transmitted through walls to neighbouring rooms or flats. That makes it the responsibility of different building trades, so a multi-disciplinary approach makes sense. Of course, this is all very well, but the way construction contracts are managed has a significant bearing on how successful noise mitigation efforts in high rise buildings will be. There is a chronic disconnection between the different parties involved in a construction project – from those that commission it, to designers and trades responsible for construction. That’s why it is imperative to pay special attention to the procurement and management practices in any multi-storey building contract. Projects always work best if the design is agreed upfront, so that costly changes during construction are avoided. While it’s critical to keep the client happy, it is also important to ‘manage upwards’ to militate against unrealistic client demands. Under pressure from their sales and marketing departments, many developers ask for layout flexibility so that, for example, bathrooms can be relocated to suit buyer preferences. This can have a dramatic impact on design and negatively affect the acoustic performance of the construction as a whole, unless it is managed well. So, to conclude, I believe the top priority to guard against excessive noise in drainage and plumbing systems is to ensure the correct pipework and installation, from mains through to appliance and vice versa. If you are unsure what to do next, talk to a supplier of equipment and pipework that can deal with the acoustics of drainage and plumbing systems. www.brymec.com • Prevent vibrations to reduce noise transmitted by the structure. This can be helped by adopting allinclusive design – considering the system as a whole – and using ‘quiet’ appliances and pipework. • Wall-mounted sanitary ware – including toilets and washbasins – tend to be quieter than floorstanding versions. A ‘close-coupled’ WC, for example, can produce around 56dB compared with just 30dB for a wall-hung WC. Noise-reducing studs can also help limit noise transmission. • Drainage pipes inevitably penetrate floors and noise can be transmitted as water is discharged from a lavatory, basin or bath, or when there is heavy rainfall. This is why pipes dropping through floors must be enclosed for their full height in each flat. • Consider the pipe material. Although cast iron pipes are excellent at reducing airborne noise, they tend to be more expensive than pipes made of other materials. However, special noise-reducing pipes are available that give effective acoustic attenuation in all directions. Consult your supplier for more information on this. • Multi-layer water supply and drainage systems are lighter, making manual handling easier and quicker, and offloading on site simpler. • Vertical stacks are best. However, where these are impractical, the designer needs to reduce pipe offset angles (which amplify noise) to a minimum. • For water supply, pipework can be manipulated on site to form bends and crossovers, giving a smoother flow and greatly reducing the number of fittings with their corresponding restrictions, giving inherently quieter supply. • Smooth internal bore of pipework does not support scale buildup or corrosion, giving better flow characteristics than traditional systems and reducing maintenance . • Attend to transitions in high-rise buildings. It’s problematic to change stack locations from one floor to another, and the transition becomes an acoustic pinch point. • Rubber-buffering and rubber-lined bracketry on pipes help minimise vibration transmission. • For drainage, specially designed stack branches allow a significant reduction in pipework for ventilation and are customisable for multipoint branch connections at each floor level. Excess noise can have a dramatic impact on wellbeing Sound advice for quieter plumbing:


Building Products January 2018
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