Sound Testing Rating Methods

Sound Testing Rating Methods

Sound tests are broken down into various sound testing rating methods. The sound insulation definition and terms are as follows:

Rating Method – RW

This single figure rating method is the rating used for laboratory airborne sound insulation tests. The figure indicates the amount of sound energy being stopped by a separating building element when tested in isolation in the absence of any flanking paths.

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Rating Method – DnTw

The single figure rating method that gives the airborne sound insulation performance between two adjacent rooms within a building as measured within site conditions. The result achieved is affected not only by the separating element also by the surrounding structure and junction details.

Rating Method – Ctr

The Ctr adaptation term is a correction that can be added to either the RW (laboratory) or DnTw (site) airborne rating. The Ctr term is used because it targets the low frequency performance of a building element and in particular the performance achieved in the 100 – 315 Hz frequency range. This term was originally developed to describe how a building element would perform if subject to excessive low frequency sound sources, such as traffic and railway noise. This rating is expressed as RW + Ctr and allows the acoustic designer to critically compare performances. The rating method has not been universally welcomed. Some acoustician believe that the method is too crude as it only considers the low frequency performance, and because site measurements at low frequencies are prone to difficulties, which can lead to a lack of confidence in the results achieved.

Rating Method – Lnw

This single figure rating method is the rating used for laboratory impact sound insulation tests on separating floors. The figure indicates the amount of sound energy being transmitted through the floor tested in isolation, in the absence of any flanking paths. With impact sound insulation, the lower the figure the better the performance.

Rating Method – LnTw

The single figure rating method that is used for impact sound insulation tests for floors. The figure indicates the sound insulation performance between two adjacent rooms within a building as measured on site. The result achieved is affected not only by the separating floor but also by the surrounding structure, e.g. flanking walls and associated junction details.

Rating Method – Dncw

This is a single figure laboratory rating method, which is used for evaluating the airborne sound insulation performance of suspended ceilings. Laboratory tests simulate the room-to-room performance of the suspended ceiling when a partition is built up to the underside of the ceiling with sound transmitted via the plenum.

If you have a project that’s needs acoustic design advice or sound insulation testing, then please contact us at: info@aptsoundtesting.co.uk or phone me (Darren) directly on 07775623464.

Sound Test Procedure

Sound Test Procedure 

The Sound Testing procedure is fairly simple and our engineer will be happy to explain this on site. Essentially, for party walls there is one type of sound insulation test which is airborne sound test and for compartment floors there are two types of sound insulation tests which are airborne and impact sound insulation tests. The airborne sound insulation test is carried out by means of a loudspeaker emitting a steady source of noise on one side of the partition (wall or floor) to be measured. The corresponding sound level is measured on the other side of the partition. Impact sound insulation tests are carried out by means of a tapping machine placed on the floor sample to be measured and the noise measured in the room or space below.

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All our engineers carry out the sound test measurements in full accordance with the measurement procedures of BS EN ISO 140-4:1998[3] for field measurements with a single figure DnTw and LnTw in accordance with BS EN ISO 717.

Ongoing problems with airborne and structure borne sound are often associated with direct noise flanking transmission through floors and supporting walls and other associated structures. One common cause of noise flanking is often associated with the inclusion of lightweight blocks within the construction of the building envelope and/or blocked cavities. It all cases it is essential to establish if your problem is due to direct transmission, flanking transmission or a combination of both so that the most cost effective remedial treatment can be chosen.

We offer both pre-construction acoustic design advice and  we can also help if your building has failed the Part E sound test. We also offer onsite inspection services to ensure that the sound insulation elements are being installed as per manufactures guild-lines.

If your require sound insulation testing and/or you would like acoustic design advice on your project, please contact us now at info@aptsoundtesting.co.uk.

Sound Intrusion Though Windows

Sound Intrusion Though Windows

Sound intrusion though windows can also be a source of great annoyance if the sound is excessive, and in some cases developments have failed the sound insulation testing due to poorly specified and installed windows. Sound intrusion may be down to a variety of factors. If the windows are operable types, the first thing to check is to see if the widows close properly against their seals and any weather stripping is continuous and in good order. If the window leaks air, then more often than not it will usually leak sound. If the window closes to form a tight seal and the weather-stripping seems adequate the next thing to check is the window frame. Windows are frequently installed in to the wall opening with plastic shims to insure the unit is plumb and level. In high traffic areas you will normally require a double glazed unit as a minimum and in some cases a triple glazed unit will be required.

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The space between the frame and the wall should be insulated and sealed before the window casings are installed. If this was not done correctly you can probably detect the sound leakage by placing your ear close to the frame and listening. The sound may be able to run along the cavity and back into the adjacent property, It is case of letting your ears do the walking and listening. If you detect distinguishable differences in sound you may have found the problem; the solution will be to remove the casing and insulate and caulk all leaks. In some cases the thickness of the glass maybe the problem in which case it may be necessary to install another layer of glass on the inside of the existing frame making sure that the additional pane of glass is well sealed into the opening.

In some instances you may be able to lower excessive sound by installing a heavy curtain – especially if the house is in a conservation area and as a result the local authority will not let you change or upgrade the windows.

If you require more advice on your project and/or you require precompletion sound testing, please contact us at: info@aptsoundtesting.co.uk  or phone me directly on 07775623464.

Remedial action following a sound insulation test failure

Remedial action following a sound insulation test failure

If a partition fails a sound insulation test, it can be difficult to provide definitive guidance on resolving specific problems that have occurred in individual buildings as the building is usually complete at the time of testing. However, using our knowledge of acoustic construction and detailing APT Sound Testing are usually able to identify and resolve any problems with the acoustic partitions.

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If the sound testing failure is attributed to the construction of the separating and/or associated flanking elements, other rooms that have not been tested as part of the testing schedule may also fail to meet the test performance levels. Additional tests may be needed, over and above the number recommended under Building Regulations Part E.

Extra sound testing will assist in identifying, at an early stage, where the failures have been caused by intermittent poor workmanship and/or design. Sound Testing may then be required for all plots to identify the ones that require remedial treatment. Where failure is due to a design fault, additional testing may not be required, as all plots with the same design are likely to require remedial treatment and so a generic acoustic upgrade can be undertaken to the failed partitions and then retested thereafter.

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To try and negate potential problems with the sound insulation testing we offer the following 4 step acoustic design advice package:

  1. Site Survey Visits – to let us view the existing site construction. This allows us to check for potential problematic construction detailing and also lets us check that the installation teams are installing the acoustic materials as per manufacturer’s guidelines.
  2. Sample Sound Testing – of the existing construction. This offers an accurate overview of the acoustic performance of the existing partitions.
  3. Design Review – a full design review of the proposed developments party walls and floors.
  4. Pre-completion Sound Testing to satisfy Approved Document E.

APT Sound Testing can supply a ‘one stop’ solution for all your acoustic requirements. If you would like more information in regards to sound insulation testing or acoustic design please contact us at: info@aptsoundtesting.co.uk  or call Darren direct on 07775623464.

Preparing for your site for Sound Testing

Preparing for your site for Sound Testing

To record accurate test measurements, we need to ensure that the correct site conditions are achieved prior to the precompletion sound testing. Relatively quiet conditions are required on site throughout the testing. Any site operatives working in the testing area will have to leave temporarily and any noisy works in the vicinity of the test areas including external site activity such as groundworks, drilling and banging will need to be halted, otherwise it may result in a sound test failure.  We always provide a full sound testing checklist within our quotation which identifies what actions need to be undertaken prior to the sound test.

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The condition the buildings/dwelling is very important, as they can influence the results of the test. The following stages for sound testing will help preparation and also assess the point at which completed buildings can be tested. Generally before the test the parts of the building/rooms either side of the separating wall or separating floor should be complete. Particular attention should be paid to the following:

  1. All separating floors and walls and all flanking walls and floors should be complete.
  2. All wall and floor junctions should be complete – to include flanking strips etc.
  3. All wall finishes should be complete, this should include skirting’s being in place. This does not include decorative finishes such as paint.
  4. Floors must be bare and no carpets should be laid – where a concrete floor with bonded resilient cover is to be fitted with wood based flooring. In this case, the test sample resilient floor cover should be tested with a wood based floor covering laid over the test sample area.
  5. Windows should be installed with all glass fitted.
  6. Trickle vents should be in place and closed.
  7. All doors should be fully fitted and closed. This includes internal doors and external doors fully fitted with doors seals.
  8. Services should be complete and any voids around ducts finished.
  9. Electrical sockets should be fitted.
  10. A 240V electricity supply should be available to all the test plots.
  11. There should be no noise during the test other than from the testing equipment.
  12. The test plots and adjacent areas within the building should be quiet for the duration of the test.
  13. No work should be carried out or noise made in the building at the time of the test.
  14. Site workers should not enter the building or be in the parts of the building undergoing a test.

We try to offer a ‘one stop acoustic solution’ visa our acoustic design service, sample sound testing and site visits.

If you would like APT Sound Testing to review your sites acoustic construction, then please speak to us about our acoustic design service, alternatively if you just require sound insulation testing please contact us at: info@aptsoundtesting.co.uk

Simple Acoustic Upgrades

Simple Acoustic Upgrades

There are many simple acoustic upgrades you can undertake to improve the sound insulation values of your dwelling. Plate A below shows one cost effective ceiling upgrade that can be undertaken on conversion projects. Firstly retain the existing floor joists – check them for general wear and tare) then above the joists install 22mm chipboard. Above the floor board install an acoustic resilient membrane and above this install the 22mm engineered floor. Within the joist cavity install 100mm AW IsoWool. To the underside of the joists fix a resilient hanger system and below this install two layers of 12.5mm sound boards ensuring that boards have adequate laps. It is worth noting that although the above system should work, it is essential that you contact us before going ahead with any works as each project is different and may require extra acoustic design input.

Plate A – Acoustic Floor Upgrade

Good Conversion Diagram - 15-01-16Also, to try and help our clients achieve compliance with Approved Document E at the first attempt we offer the following 4 step acoustic design package:

  1. Site Survey Visits – to let us view the existing site construction. This allows us to check for potential problematic construction such as inclusion of lightweight blocks in the existing construction. It also lets us check that the installation teams are installing the acoustic materials as per manufacturer’s guidelines.
  2. Sample Sound Testing – of the existing construction. This offers an accurate overview of the acoustic performance of the existing partitions which enables us to offer a targeted acoustic design using the sound insulation performance of the existing construction.
  3. Acoustic Design Review – a full design review of the proposed developments party walls and floors.
  4. Pre-completion Sound Testing to satisfy Approved Document E.

APT Sound Testing can advise on all types of acoustic design, whether it’s accomplished during initial construction or during a refurbishment/renovation project. We also undertake UKAS accredited sound insulation testing providing a ‘one stop’ solution for all your acoustic requirements.

If you would like more information in regards to sound testing please follow our blog at: http://soundtestinguk.blogspot.co.uk or contact us at: info@aptsoundtesting.co.uk and 07775623464 or visit our website at: www.aptsoundtesting.co.uk

Noise Damping to Improve Sound Testing

Noise Damping to Improve Sound Testing 

Noise damping is the most efficient and effective ways to control vibration and noise radiation at the source. Damping materials lessen this noise by turning the vibration into a low-grade heat. By using viscoelastic materials, it changes the resonant frequency of a substrate. By combining vibration damping materials and sound absorbers a composite acoustic construction can be achieved, that can control both airborne and structure borne noise – the final element for good soundproofing.

acoustic_wall_upgrade

It is worth noting that a  large number of manufacturers now produce a wide range of systems designed to improve sound insulation in homes and commercial buildings. In all instances, the effectiveness of these materials will vary depending on the situation in which they are installed. When choosing the acoustic product/s, detailed information on the likely sound insulation performance should be requested from the supplier. If you have an existing property you should check the existing construction of the dividing wall/floor partitions and work back from there. You are advised to give careful consideration to the data supplied by a manufacturer before using a proprietary product. it is also worth noting that the sound insulation value/s given for each product will be ‘best case’ as they have been tested in laboratory conditions and not on site – this is usually worse result by up to 3-5 dB) which may be the difference between a sound test pass or failure.

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Also when undertaking remedial work to improve the sound insulation, the acoustic materials are often quite heavy which may result in considerable weight being added to the structure of a property. Thus it is essential to check that the ceiling or floor joists can carry the increased loads satisfactorily.

So in a nutshell if you allow for the following four main elements of sound insulation on your acoustic partition design; Decoupling, Absorption, Mass and Damping, your development should pass the sound insulation test at the first attempt.

If you would like more information in regards to acoustic design and sound insulation testing, please contact us now at info@aptsoundtesting.co.uk or call Darren direct on 07775623464.

Noise Absorption

Noise Absorption

It is usual for air cavities to resonate, such as the cavity within a timber wall. For instance if you blow across the top of a bottle and heard the sound, it sounds much louder; this is the trapped air resonating. In a similar way a hollow wall will also trap air that will resonate. When the wall is vibrated by loud sound such as a neighbour’s loud music of TV, the air in the wall cavity will vibrate just like a drum. Unfortunately this air cavity is another means for sound vibration to travel from one side of the acoustic partition wall to the other. So even though the wall framing may be decoupled, the vibrating air cavity may still transmit some sound through the wall between the wall studs. Acoustic fiberglass insulation will absorb some of this (absorption).

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In all instances acoustic Insulation should help the overall sound insulation test result, and should always be installed if possible. Although the vibration reduction is smaller than the other 3 elements it is still very important.  The key is to keep the density low, so don’t try to compress or pack the insulation as the vibration may use this to bridge the construction.

So to summarise we have now managed to de-couple and insulated the acoustic wall framing, which has helped to stop much of the vibration, but unfortunately not all of it. So what else can we do? – add mass of course. A full explanation of how mass can help your sound test results can be found in the next blog.

If you require any information on our acoustic design and/or sound test services, please contact us at info@aptsoundtesting.co.uk or call Darren on 07775623464.

Noise Problems in Refurbished Industrial Buildings

Noise Problems in Refurbished Industrial Buildings

We often get asked to undertake a series of sound test measurements to establish the acoustic performance of the wall of floors construction in existing buildings where the dwelling owners are concerned about excess noise.

In recent years the refurbishment of old industrial buildings into residential dwellings has become a very popular. Frequently the existing finishes of existing concrete, brick or wood Noise Problems in Refurbished Industrial Buildingsare left as the interior finish, supposedly to provide the “loft” type of décor. Such designs require even more acoustic design attention if sound privacy is to be achieved. Potential noise problems in refurbished industrial buildings can be quite challenging so buyers should insist that actual on-site sound insulation testing is undertaken to check the building has complied with the sound design performance criteria of Building Regulations Part E.

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If you think you have a sound problem in your dwelling and are seeking help to resolve the problem, be sure to contact us and describe the problem in as much detail as possible. Describe the nature of the sounds, when and where you can hear it. Is it impact noise or airborne noise or a combination of both? If the unit is of recent construction you may need to procure a set of architectural drawings and mark-up which partitions noisiest. The more information you can provide us, the quicker we can try to determine the nature of the problem and subsequently find an acoustic solution for the partition/s.

We can also visit site and undertake sample testing on the dividing partitions. If the partitions fail the tests we can identify the main reasons for the sound test failures so targeted remedial treatments can be undertaken.

If you have a project that requires acoustic design advice or sound insulation testing, then please contact us at: info@aptsoundtesting.co.uk or phone me directly on 07775623464.

 

Ceiling and Wall Assemblies for Part E

Ceiling and Wall Assemblies for Part E 

In our experience ceiling and wall assemblies, can be the main pathways for the two main types of sound transmission. The first type is the airborne sound –  such as loud music) and the second is impact sound, such as footfalls on the floor above.

If the ceiling and wall assemblies have been designed and constructed to provide adequate airborne isolation, impact noise can still be a problem. If the finished floor surface has been designed to accommodate carpeting, the carpeting and under pad will normally provide a good degree of impact sound isolation. On the other hand, if the finished floor is floor is constructed in hardwood, stone or ceramic tile. Achieving good impact sound isolation requires much more attention at the design stage to prevent potential sound test failures.

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One of the main misconceptions is sound simply passes through materials, this is not the case. Sound waves are form of energy that energises any material that the sound waves come in contact with. Thus sound energy that impacts on a wall for floor/ceiling assembly will cause the material to vibrate like a radio speaker; the energised material then becomes the transmitter of the sound energy.

Thinner, more lightweight building materials often hold the key to effective noise control, by using materials with different acoustical characteristics that will dissipate and diffuse the sound energy. Insulation in the cavity converts some of the energy in to heat while a resilient channel will help minimise the direct connection of the gypsum board from one side of the assembly to the other. Each material and its relationship to one another, produces small increases in sound isolation that in turn reduces the transmission of sound through the whole system and subsequently improves the sound insulation characteristics of the acoustic partitions.

I hope the above article helps to explain the importance material selection within acoustic design.  If you would like more information or some acoustic design advice on your project, please don’t hesitate to contact me on info@aptsoundtesting.net or call me on 07775623464.