Silence is Golden: Designing in Acoustic Comfort

Internal noise in residential buildings can be a real pain point for residents and homeowners alike. Here, we take a look at why closed cell acoustic insulation could be the answer.

There are many reasons why noise is now one of the most common causes of aggravation is residential buildings. For a start, we’re all getting noisier through the use of entertainment devices such as tablets, smart phones and portable music players. Add to this lightweight construction techniques, more open plan living and hard flooring and you have the perfect ingredients for a disturbed night’s sleep.

The simple fact is that unless modern homes are fitted with sound proofing measures, and that includes plumbing pipework and rainwater systems, they will become a source of noise irritation for occupants.

Although lightweight partition walls and ceilings are now commonly used in new builds, they are not very effective at blocking noise because they can act like a drum. By that, we mean the drywall creates a membrane on the two outward surfaces of the structural framework, with the void in between filled with air. As the sound waves from plumbing or rainwater pipes strike one surface it is carried through the air to the outer surface where it manifests as audible noise in the adjacent rooms.

Soil pipes and other plumbing installations are commonly routed through this void, meaning any noise created by rushing water or expansion and contraction of pipework is clearly audible in adjacent rooms. With the ability of soundwaves to travel some distance and the two sides of the partition wall acting like a drum, this noise can soon become a major irritant, especially in multi occupancy residential buildings.

Soil pipes are also notorious for causing disturbance where water impacts the sides as it changes direction through a bend or junction. It’s not helped, either, by the flow rate varying from zero to several litres per second when a toilet is flushed or a bath is emptied, whilst the volume of water travelling through a straight section of pipe generates noise in itself. It’s made worse by drainage pipes in three-storey town houses or multi-occupancy buildings travelling long distances over many floors. This can cause the pipe to vibrate and make screeching, whining or rattling noises, although this can occur in traditional two-storey properties. All pipes in a building will tend to vibrate at least slightly whenever water passes through them, again another source of noise.

Rainwater systems are another common source of noise and this has become more noticeable over recent years because of the popularity of lightweight gutter and downpipe materials that are often routed inside the building envelope.

The answer

In all these situations an effective approach is to use a material that absorbs the sound waves, which means that it has to be ‘soft’. These kinds of materials are now routinely used for acoustic ceilings and padded carpets, although, until relatively recently, plumbing systems, one of the single largest contributors to noise disturbance, was overlooked.

Latest flexible technical insulation materials are designed specifically to tackle noise from plumbing and rainwater systems. They are manufactured from a 2mm thick foil faced acoustic EPDM-EVA barrier with 4kg/m2 weight and a 9mm thick elastomeric foam layer for decoupling and reducing airborne sound, like that on ArmaFlex, which makes it more effective compared to traditional acoustic insulation products. Independent tests showed that flexible insulation foams like this achieve a much greater reduction in sound level and with a thinner wall thickness. Independent tests were carried out by CSTB (Centre Scientifique et Technique du Bâtiment) and confirmed that our acoustic foams are able to reduce airborne sound pressure level of a Geberit roof drainage system by 16 dB (A) at 2 l/s water flow.  Similar tests on a PVC pipe, where the vibrations caused by flowing water are stronger because of the lighter weight PVC, achieved a noise reduction of 12 dB (A). The human ear perceives a reduction of 10 dB (A) as halving the volume.  By choosing the correct flexible acoustic foam it is possible to achieve a weighted sound reduction index (Rw) up to 28 dB when pipe and elbows are insulated.

These new flexible technical insulation materials have very good acoustic damping and acoustic isolation properties across the frequency range relevant for building acoustics – irrespective of whether it is installed on cast iron or PVC pipes. They also display very good fire behaviour, achieving the best fire class for organic products in the European SBI test. Developers will find that the thinner thicknesses required to achieve the required decibel reduction is an advantage because it makes installation in tight spaces much easier.

Where insulation is specified to tackle noise nuisance it should be of the waterproof, closed-cell type, such as nitrile rubber foam. This will prevent it absorbing water, allowing it to be used internally, where condensation on pipework could be an issue, and externally for rainwater systems.

A good night’s sleep

In the past, building acoustics wasn’t factored in at design stage. That is now changing and more designers and their clients are taking account of all noise sources. Admittedly, the area of acoustics can leave people baffled, yet, by taking a few simple steps such as specifying closed insulation, it can be relatively straightforward to design out, but much more difficult to tackle after handover.

So, if the sound of rushing water from the toilet or rainwater system is causing disruption in your multi occupancy buildings, multi-layered, closed cell insulation provides an easy solution. Noise has become a by-product of modern living, where it has the ability to disturb sleep and generally compromise our quality of life. Your clients may not yet know it, but they no longer have to put up with it.

The new ArmaComfort AB Plus and ArmaComfort AB Alu Plus acoustic insulation materials are available from SIS.

If you have a project that requires an effective noise solution, speak to the team here at SIS and we’ll be able to help you select the right product for your project needs. See our full range of acoustic products here, or call us on 01279 871159.