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).

installing_acoustic_wool

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.

Decoupling of Materials

Decoupling of Materials

There are many things to consider with your acoustic design and construction, one of the first – and most important) is the decoupling of materials or also know as isolation of materials. Sound travels easily along direct construction pathways, i.e. if the construction is made up of a wooden wall frame with a layer of plasterboard fixed to either side, with this type of construction the sound has a solid mass of materials to travel across. If we “decouple the materials” it reduces the pathway for vibration and the sound levels drop accordingly.

When we design for acoustic partition construction we obviously want less sound vibration to travel from one side of the wall to the other. It is therefore hugely beneficial if we can decouple the partition framing in our walls and ceilings. Decoupling is a simple, inexpensive and highly effective way to improve the sound insulation results for Building Regulations Part E.  .

There are many types of decoupled construction that in turn offer varying degrees of separation of the drywall on one side from the drywall on the other side. For instance the image below shows a twin wall construction which is far superior to a single stud wall. if you require good sound test results, this is one of the best types of construction.

decoupled_wall_construction

By decoupling the wall studs limits by providing a cavity or break between the two walls reduces the vibration trying to conduct through the wall. although this will improves the airborne results, other improvements will still be required.  So although our decoupled framing system reduces a good deal of vibration, we need to continue to the other 3 elements, absorption, mass, and to damping to reduce the noise more effectively.

Our next blog will consider absorption and how it can make a  large difference to sound test results. If you would like more information to acoustic design and/or sound insulation testing please contact us at: info@aptsoundtesting.co.uk or call Darren on 07775623464.

The Main Sound Proofing Elements

The main Sound Proofing Elements

Coupled Wall Construction

We often get asked ‘how can we improve our soundproofing on our development. The first thing to understand is the basic of soundproofing design and construction. If you understand the basics, you’ll have a more educated view point in regards to the way sound and vibration behaves within your new dwellings. Basically, we want to stop sound and vibration through the walls and floors of your development and one of the best ways of doing this is avoiding coupled wall construction. In general, we are trying to stop vibrations from getting to “your” side of the wall or ceiling.

The plate below shows a typical wall and noise problems associated with it. With this type of construction noise transference is a big problem. If there is even moderate levels of noise on one side of the wall the chances are you will hear it.

coupled_wall_construction

If you look at the red arrows in the above diagram it clearly shows how sound is conducted from one side of the wall to the other. As the wall elements are firmly fixed against each other, i.e. the plasterboard is rigidly connected to the timber, the vibration conducts straight through the whole wall construction.

If you look at the blue waves this indicates airborne transmission. The plasterboard is vibrating back and forth which produces a sound wave in the wall cavity. This, in turn, vibrates the plasterboard on the opposite side of the wall. the whole construction acts like a  huge diaphragm or like a large speaker with both sides of the wall vibrating in unison, which is not ideal.

Our next blog will explain how we can reduce noise transmission by decoupling the wall construction. if you would like more information on our sound testing or acoustic design services please contact us now at: info@aptsoundtesting.co.uk or call Darren direct on 07775623464.

Reducing Noise in Residential Buildings

Reducing Noise in Residential Buildings

We often get asked how noise can be reduced in residential buildings such as apartments or terrace houses. One of the most common problems is noise transmission through the floor and ceiling assemblies in flats and through the wall partitions in houses. The usual noise problems range from airborne noise transmission from voices TVs and music to footfall impact noise caused by high heels on wooden/tiled floors.

Noise_Problems_Failed_Sound_Testing

In most cases for newer residential units many of the problems could have been prevented in the first place, if more attention had been paid to noise control during the design and construction process.   If the acoustic design has not been taken into account from the off-set of the project, then it becomes far more problematic and costly if noise problems are discovered and the partitions fail the sound insulation testing during the per-completion testing.

If you are contemplating the purchase of a unit, do not be afraid to question the contractor and the real estate agents about the sound insulation results for the unit. Ask if any of the units failed during the precompletion testing. In some cases just because a sample of the units had been tested during prior to handover doesn’t mean unit has been sound tested.

If you are not happy with the sound insulation properties of your unit then you may have a case to demand corrective action at the expense of others. If you have a noise problem that is not resolved and you go to sell your unit, you may be compelled to reveal the deficiency to a prospective buyer which may have an impact on the selling price.

If you need acoustic advice on your project, please don’t hesitate to contact us no at: info@aptsoundtesting.co.uk or call me direct on 07775623464.

Airborne and Impact Sound Tests

Airborne and Impact Sound Tests

You are required to undertake two types of sound testing to comply with Building Regulations Part E, they are Airborne and Impact sound tests. Airborne sound tests are undertake on wall and floors and impact tests are undertaken on floor only.

To test the sound insulation properties of a floor or wall via airborne sound testing, you need to provide a sound source which consists of an amplifier and loud speaker is set up on one side of the wall or floor partition that is to be tested. We then turn the setting to turn on Pink noise. Pink noise sounds like the static that can be heard on a radio that is off station. Pink noise is used  because it is made up of a wall of sound that has a wide spectrum of frequencies. This provides an indication of sound insulation performance for a wide range of sounds that may be experienced within a dwelling from musical instruments to loud TV noise sources.

sound testing

The pink noise is measured in the room which contains the speaker or sound source using a Class 1 Norsonic sound level meter; thereafter the noise is measured on the other side of the wall or floor partition that is being tested. In layman’s terms the difference between these two levels is the amount of sound that is stopped by the sound insulating qualities if the wall or floor partition/s. The result is then corrected and adjusted depending on the echo or reverberation time within the receiving room, and any background noise such as builders work noise etc.

To test the impact sound insulation performance of a floor, a Norsonic tapping machine which consists of five small hammers that are dropped onto the floor to simulate foot fall, is placed on the floor. The resultant noise in the room below is measured with a Norsonic Class 1 sound level meter and the amount of noise that passes through the floor is the impact sound transmission level and is expressed as a single number. This result is then corrected and adjusted depending on the reverberation time of the rooms as well as any background noise to give the impact sound transmission result (LnT,w).

Impact Sound Testing

Both types of sound tests results are then compared to the performance criteria of Approved Document E, which stipulates that airborne sound needs to achieve 45dB for new build & 43dB for conversion projects. To achieve a pass for impact sound testing you need to achieve 62dB for new build & 64dB conversions.

If you have a project that’s needs acoustic design advice or needs precompletion sound testing then please contact us at: info@aptsoundtesting.co.uk or call us directly on 07775623464.

Sound Testing Services for New Dwellings

Sound Testing Services  for new dwellings

Sound Testing Services became mandatory in England & Wales in 2003, when Approved Document E was updated. Approved Document E requires new and converted to achieve a reasonable level of sound insulation between dwellings. The easiest way simplest way to comply with the requirements of Approved Document E; is to have on-site pre-completion sound insulation testing carried out on your project.

Many of our clients are clients are apprehensive prior to having to undertake pre-completion sound insulation tests.  This is often down to the fear of failure; however if the the acoustic design specification has been undertaken from the offset of the project and is closely followed during the construction phase then he chance of potential failure is greatly reduced.

sound testing equipment

Approved Document E requires a minimum of one ‘set’ of tests for every ten units in each group and/or sub group.  This is usually broken down to two airborne wall, two airborne floor and two impact sound tests. If you have a development of 25 houses, with five different sub-groups (5 units in each) then you would usually conduct 5 ‘sets’ of tests.  If no separating floors are available, i.e. in semi-detached or terraced houses, one set of tests would consist of two airborne tests of separating walls only.

If the precompletion test results do not satisfy the performance criteria of Approved Document E, then our test engineer will attempt to determine the possible causes of failure. This may be to do with construction detailing around services or at junctions, or simply, poor acoustic design. Once a specific reason for failure has been determined, we can then advise the client on remedial actions that can be undertaken.

If you have a project that’s needs acoustic design advice or needs precompletion sound testing then please contact us at: info@aptsoundtesting.co.uk or call us directly on 07775623464.

Successful Sound Testing in London

Successful Sound Testing in London 

From the offset careful consideration should be shown to the acoustic design detailing for both conversion and new build projects if you are to achieve a successful sound testing in London at the first attempt.

For instance many of the dwellings in London consist of flats converted from large Victorian houses. At the time of the original build some 100 years ago, designing for sound insulation was not a consideration and so many of the dwellings suffer from adverse noise transference between the floor and wall partitions. This can be extremely stressful to the occupant’s well-being is a major cause for concern.

ACOUSTIC_DESIGN

There are ways to improve the airborne and impact performance by improving the wall/floor partitions ability to reduce the amount of sound transmission from one side of a construction element to the other and subsequently  from dwelling to dwelling. By adding isolation and  mass to the floors and wall construction compliance with Part E for conversion projects can be achieved.

To help our clients achieve successful sound testing we offer the following ‘3 step package’:

  1. Sample Sound Testing of the existing building. 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.
  2. Acoustic Design Review of the proposed developments party walls and floors to ensure acoustic details with be sufficient to pass Building Regulations Part E
  3. Site Survey Visits to check that the onsite construction is being undertaken in-line with manufacturer’s guidelines.

In our experience if the acoustic design is taken into consideration from the offset of the project, then it usually results in compliance with Building Regulations Part E.  In many cases sound test failure is down to poor acoustic design and poor workmanship, that is why we offer the 3 step process to achieve successful sound testing on your London project.

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 us directly on 07775623464.

Sound Testing Terminology (2 of 3)

Sound Testing Terminology (2 of 3)

Often confusion can arise from the large amount of ‘terms’ used in conjunction with acoustic design and sound insulation testing. To help with this we have made a list of the following terms for clarity – this is the second of three blogs:

Façade Testing  – This Standard – ISO 140-5:1998) specifies the testing methods to evaluate the sound insulation in buildings and building elements for facades. Three rounds of a proficiency testing scheme for airborne sound insulation measurements have been performed according to the methods specified in the standard for a whole facade by using an external loudspeaker as the noise source.

sound testing equipment

Flanking element (flanking wall) – This is any building element that contributes to the airborne sound or impact transmission between rooms in a building which is not the direct separating element (i.e. not the separating wall or separating floor).

Flanking strip or edge strip – This is a resilient strip using foamed polyethylene normally 5 mm thick, which is located at the perimeter of a floor to isolate the floor boards from the walls and skirting.

Flanking transmission  – This is airborne or impact transmission between rooms that is transmitted via flanking elements and/or flanking elements in conjunction with the main separating elements. An example of a flanking element is the inner leaf of an external wall that connects to the separating ‘core’ of a wall or floor.

Flexible closer – This is a flexible cavity stop or cavity barrier which seals the air path in cavities linking adjoining dwellings.

Floating floor treatment (FFT) – This is a timber floating floor system which may use battens, cradles or platform base, all of which use a resilient layer to provide isolation from the base floor and adjacent wall elements.

Gypsum based plasterboard  – This is a dry lining board applied to walls, ceilings and within floating floor treatments which has gypsum content. It may also have fibre reinforcement within the board.

Impact sound – This is sound which is propagated from a noise source through a direct medium. An example of this is footfall on a floor.

Impact sound transmission – This is sound which is spread from an impact noise source in direct contact with a building element.

We hope the above information in regards to Sound Testing Terminology has been helpful. If you would like more information in regards to acoustic design and sound testing services, please contact us at info@aptsoundtesting.co.uk or visit our website at: www.aptsoundtesting.co.uk

Broken Down Rating Methods for Sound Testing

Broken Down Rating Methods for Sound Testing 

The sound insulation rating methods that follow are defined in:

Sound insulation testing is usually undertaken near the end of a project to show that the party wall and floor partitions meet the standards shown in Building Regulations Approved Document E.  The method for testing for airborne and impact sound insulation is in full accordance with: the suggested methods presented in BS EN ISO 140-parts 4 & 7: 1998. Sound tests are broken down into various rating methods.

sound testing equipment

The sound insulation rating methods that follow are defined in:

 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.

 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

acousticians 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 forclaboratory 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

The 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.

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 have the technical experience to help identify and rectify your soundproofing or noise control problem.

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 or visit our website at: www.aptsoundtesting.co.uk

The different types of Sound Testing

The different types of Sound Testing.

There are two distinct types of noise to consider through floors, they are:

  • Airborne Noise (for example speech and music) and
  • Impact Noise (for example footsteps directly on the floor above)

To take this into account there are two different types of Sound Testing required in compliance with Approved Document Part E. Even if both types of sound are emitting through the ceiling/floor then there are some easy installations that should reduce the sound levels and improve your sound test results.

sound testing equipment

To help our clients overcome this problem, we also offer our acoustic design service which helps clients to pass the sound testing upon completion of the acoustic upgrade. By advising on a simple cost effective wall and/or floor upgrade, we are able to forward simple to follow acoustic design reviews, utilising our extensive knowledge of different materials and construction methods. Using this philosophy, to date, we have had no sound test failures where our acoustic upgrades have been incorporated into the site construction, ensuring compliance with Part E of Building Regulations.

Pre-completion sound testing has been a mandatory requirement since July 2003 and all new build properties and conversions which were built after this date require 10% of each party wall/floor construction type to be tested. The Sound testing is to be carried out between pairs of rooms separated by party walls and/or floors. Part E stipulates that it sound testing should take place between dividing partitions between living rooms and bedrooms as these are classed as the two main habitable rooms; however, other rooms can be used if this is not possible such as dining rooms, kitchen and studies.

APT Sound Testing can undertake UKAS accredited Part E sound testing throughout England and Wales. Our sound test engineers carry all the latest class 1 acoustic equipment and we provide full UKAS accredited air and sound testing, so our clients can be sure that all testing is completed to the strictest  ISO quality controlled standards.

If you would like advice on your acoustic design or sound testing in London, please contact us now at info@aptsoundtesting.co.uk or call us on 07775623464