Posts Tagged ‘Acoustics’

Newcastle Sixth Form College building tour

24/07/2013

Newcastle Sixth Form College moves into the only purpose-built sixth form college in the city this month, providing a world-class learning environment for its students. Below is the college’s 3D building tour – it was designed by RMJM.

The 11,000m2 inspirational building will provide 16 to 18 year olds across the region with specialised facilities in classrooms, performance studios and laboratories. Each room has been fitted to the highest standards and is well equipped to allow the delivery of high quality teaching that will stimulate student learning. Each floor will also have open access IT areas to allow for private study.

In the college’s fine arts studio, Hunter Douglas met the challenge of the sloping ceiling details in the design with bespoke systems that also conceal services and provide acoustic control, as well as offering aesthetic value and long-term solution.

acoustic sloping ceiling

Hunter Douglas on ESI.info

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Why aren’t we all enjoying a quiet night’s sleep?

31/07/2012

The introduction of Building Regulations Part E in July 2003 represented a big step by which all residential developments in England and Wales had to undergo pre-completion acoustic tests and meet certain airborne and impact sound performance figures. In 2004, building to Robust Details was added to this, providing an alternative method to pre-completion testing to show compliance with the Part E of the Building Regulations. So – nine years on, is everything as quiet as a mouse?

Patrick Dent, AMIOA MEng and Technical Director of Total Vibration Solutions Ltd, explores the issue of noise.

Image by Romana Klee on Flickr

Have these regulations meant that all new build dwellings and those formed from a material change of use are being constructed in a way that provides no noise issues and leaves each and every resident as happy as the proverbial Larry? Well, the simple answer is no. My weeks rarely go by without speaking to an individual who is having noise issues within their newly constructed apartment or house, yet when we investigate their complaint we find that the development met the requirements of Approved Document Part E of the Building Regulations.

So what’s going wrong? Do we need to revise Part E of the building regs? Are we overlooking certain things in the testing? Or do the regulations simply not give a result that the end client deems acceptable?

In truth, there are a wide variety of reasons why we are still encountering noise problems. One factor that caused a great deal of issues originally – although a lot of developers and specifiers are now aware of this trait of certain materials – was the problem of creep. Acoustic underlays and under-screed materials, which offered good acoustic performance initially, would continue to deflect under load over time and not recover to their original thickness. This would result in the resilience in the floor being lost, floors dropping, and floors that met the pre-completion testing initially, suddenly failing six months later.

This is quite an easily rectified problem that can be overcome by developers and specifiers ensuring that they do not use materials that are susceptible to creep. Foams are particularly prone to creep, so any foams used in this capacity should be closed-cell and cross-linked, however any reputable manufacturer or supplier should have test data available on the creep performance of their materials.

The more complex problems come when we investigate noise complaints where there clearly is a noise problem, and yet the development still passes the impact and airborne tests required to comply with Part E of the Building Regulations.

One such example I was made aware of recently involved some luxury apartments where the occupants had got together and complained that the sound insulation in the floors of their apartments were not good enough. An acoustic consultant was called in to independently test the floors. The results gave on average an airborne DnT,w+Ctr of 50dB (Part E requires a minimum of 45dB for new builds and 43dB for dwellings formed by material change of use, which the apartments actually were in this case) and an impact figure LnT,w of 52dB (Part E requires a maximum of 62dB for new builds and 64dB for material change of use). In other words, figures that any developers would be very happy with, and that were comfortably within the requirements of the building regulations.

However, what the acoustician did notice was the incredibly low background noise level. So although the noise levels caused by people walking above wouldn’t be noticed within a building with a more “normal” level of background noise, in these luxury flats, such dramatic but inconstant changes in noise level makes the sound very audible and quite disturbing.

A lack of background noise makes occasional sounds all the more noticeable

This brings us to the fact that an individual’s threshold of hearing and their perception of noise will change depending upon the environment that they are in. Part E of the Building Regulations doesn’t take the background noise level into account – so in this case, the occupants of these luxury flats are left feeling aggrieved at what they perceive as poor sound insulation in their building, whilst the builders would point to the testing that shows they have more than exceeded the requirements. So who is at fault?

Problems with background noise levels aren’t the only issues that we see on a regular basis. There is a widely accepted agreement that the tapping machine used in ISO 140 does not provide an accurate reproduction of the noise produced by footfall. Similarly, the test does not consider the low frequency performance and given that what you are hearing – particularly in dwellings formed by material change of use with timber floors – is caused by the deflection of the joists induced by the footfall, which produces sound at much lower frequencies than 100Hz, the ISO 140 calculation methods ignore it.

AcoustiCORK™ agglomerated cork underlay for impact noise and thermal insulation

So does this mean that the tests are useless and we should completely overturn them? Well, the simple answer is no. In the majority of cases, Part E provides a very good standard to ensure that the end occupant is not disturbed by noise. But here is where we need to be careful. It is a standard. It is the minimum requirements that a building needs to achieve. Certain circumstances, such as a low background noise level, a higher degree of luxury etc., will dictate that the builder needs to achieve a far greater level of sound insulation.

You wouldn’t fit out the furniture of a student hall of residence in the same way you would million pound apartments. Neither should you treat the sound insulation in the same way.

Case study: soundproofing a music room using folding sliding doors

09/07/2012

Doors, by nature, will allow a certain amount of noise to escape. However, there are specialist designs and techniques available to help alleviate the level of audible sound. Here is how Baca Architects and Sunfold Systems solved a musical soundproofing dilemma.

The clients wanted the music room to have an open, airy feel

A client approached Baca Architects, requesting that as part of their home they wanted a music room. This room was to form an important element of their living and leisure time.

A central point of the house was perfect for their requirements for entertaining guests and a key part of the family’s time together, but when it came to the times where privacy was required, they needed to be able to close the doors for recording purposes.

To create the open feel the clients required whilst also having the option to shut off the music area, lead architect Robert Barker wanted to incorporate interior folding sliding doors as an effective and visually appealing solution to the overall project. “Noise transfers so easily through most doors, so it was important for the internal folding sliding doors we used to be flawless, to create a balanced sound level,” he commented.

The music room had to be soundproofed for recording purposes

Robert chose to use Sunfold Systems’ timber range of folding sliding doors, the SFK69 painted in white. This is the highest specification timber system available, and is manufactured from triple laminated solid timber sections. As noise control was key, it was vital that the joints, tracks, frame construction and head detail connectors had no air gaps, to make sure that there was no flanking sound either side.

By using slim-width panels and through the natural slim sightlines of the SFK69, both the structure and the appearance of the internal sliding door system worked well together to achieve the desired effect.

Soundproofing sliding folding doors