LABORATORY SOUND TESTING COMPARED TO ONSITE SOUND TESTING

LABORATORY SOUND TESTING COMPARED TO ONSITE SOUND TESTING

We at APT often get asked why a design that has passed easily in the laboratory has struggled – and sometimes failed to pass the sound testing for Part E

Despite site contractor’s best endeavours, it is extremely difficult to build to the stringent exacting standards of the test laboratory. When the construction assembly is undertaken in the lab, it has gone through an exacting installation technique prior to the sound test, which is the reason why better sound testing levels are achieved.

Throughout the acoustic installation the manufacturer’s guidance is followed to the letter by the lab technicians. Although, this should be replicated on site, it seldom is and so a design which can be robust and well in excess of Part E requirements can lose 10dB or more compared to the results achieved in the laboratory. Unfortunately there are many reasons why this occurs and it’s usually down poor quality operatives and other on-site other issues such as cost, time and programming constraints come into play.

We have undertaken many sound tests where the acoustic design details showed the partitions should achieve in excess of 50dB, only for it to fail with sound test results below the required 45dB.  This is why a 7-9dB tolerance should be allowed between the dB rating of the acoustic solution and the onsite construction. Unfortunately, if cost constraints come into play and subsequent allowances aren’t made for the onsite acoustic performance there is a high probability it will fail the sound testing, which may lead to expensive remedial works as well as delayed handover which will be far more expensive in the long run.

sound testing

There are many reasons why the onsite construction results are worse than the laboratory,   issues such as such as using the wrong fixings and not installing the insulation to name but two. Either of these can easily lead to a sound test failure.

It is very important that acoustic installation details are closely followed to ensure that the onsite results are as close as possible to the laboratory target. We offer an acoustic design service, to help you achieve Part E compliance at the first attempt.

The following list explains what should be done to achieve a successful sound tests and Part E compliance:

  1. Ensure that the construction team is fully briefed of the acoustic details.
  2. Ensure that the manufactures installation booklet is on site at all times.
  3. Ensure that the Acoustic floor is fitted with staggered joints.
  4. If you are installing floating screed ensure all isolation layer joints are overlapped and taped.
  5. Ensure all the Acoustic floor is sealed watertight even around heating pipes.
  6. Do not nail or screw through an Acoustic Floor.
  7. Do not screws plaster board into joists, when using a Resilient Bar system.
  8. Ensure the insulation fills the whole width of void
  9. Pack around pipe work and double board with staggered joints.
  10. Ensure that the plasterboard on any walls is complete right down to within 5-10mm of the subfloor and seal all gaps.
  11. Ensure you use the isolation tape around the wall of each room.
  12. Ensure plasterboard is fitted with staggered layers and all joints sealed.
  13. If using Resilient Bars ensure that they are fitted as per manufacturer’s recommendations.
  14. Ensure all Fireplaces are blocked up with brick or a twin lined plasterboard system and filled with acoustic insulation.
  15. Ensure that any RSJ’s or supporting steel work is insulated and isolated from plasterboard.
  16. Ensure all waste pipe service runs are boxed in with insulation and plasterboard.
  17. Ensure all doors and windows are installed before the test is carried out, to stop noise transference.

APT offer an acoustic design service to make sure the acoustic elements are being installed as per the manufacturer’s guidelines, if you are worried about passing your sound testing at the first attempt please don’t hesitate to contact us now at: info@aptsoundtesting.co.uk or visit our website at: www.aptsoundtesting.co.uk

 

Quantifying Sound levels for Sound Testing Failures

Quantifying Sound levels for Sound Testing Failures

APT Sound Testing often ask us about the parameters behind the sound testing under Part E. To try and clarify sound levels in more detail we have written a brief explanation.

What is sound or Noise?

Noise or sound  is often defined as unwanted sound. Sound is defined as any pressure variation heard by the human ear. The sound pressure level (SPL) is a measure of the air vibrations that make up sound. Because the human ear is sensitive to a wide range of pressure levels, the SPL is measured on a logarithmic scale with units of decibels (dB).

NoiseFlankingWall

How do we  perceive noise or sound?

Healthy human ears perceive pressure variations over a wide range of frequencies — from low as low as 20 Hz to frequencies as high as 20,000 Hz. The human ear’s range starts at the threshold of hearing (0 dB) and ends at the threshold of pain (around 140dB) which would be the same as standing next to a large jet engine.

The human ear is less sensitive to sounds in the low frequencies compared to the higher frequencies. For example, a 50 Hz tone must be at a level of 85 dB in order to be perceived by the human ear as being the same loudness as the higher frequency 1000-Hz tone at a level of 70dB

How do you quantify sound?

As mentioned above, sound levels are usually measured and expressed in decibels (dB). Most environmental noise does not consist of a single frequency, but rather a broad band of frequencies differing in sound level. The intensities of each frequency add to generate sound. The method commonly used to quantify environmental sounds involves evaluating all of the frequencies of a sound according to a weighting system which reflects that human hearing is less sensitive at low frequencies and extremely high frequencies than at the mid-range frequencies. This is called “A” weighting, and the decibel level measured is called the A-weighted sound level (dBA).

Quantifying sound testing failures

As a rule of thumb, a doubling in the loudness of the sound occurs with every increase of 10 dB in sound pressure. In other words, for most individuals a 60 dBA noise would sound twice as loud as a 50 dBA noise.

If a sound testing fails, the client often asks by how much. When we confirm it has failed by 5dB they usually say ‘if that’s the case I only need to improve the partition by 10%’, unfortunately that isn’t the case – the partition has actually failed by 50% subsequently the partition will need major upgrades to pass the sound testing under Part E of Building Regulations.

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

SOUND TESTING AND THE MAIN NOISE FLANKING PATHS

SOUND TESTING AND THE MAIN NOISE FLANKING PATHS

One of the most common reasons for partitions failing the sound testing is down to noise flanking between partitions.

Noise Flanking is a term used by acoustic engineers wherein the sound passes over the top or under the primary partition separating the two spaces under test. Flanking sound transmission can be especially bothersome in multi-family residential buildings do to the sheer number of dividing partitions.

One way to reduce the chance of to flanking transmission/s is at the design phase of the dwelling. Unfortunately, by Simply specifying high performance wall and floor partitions between dwelling is no guarantee to a sound isolation and subsequently a successful sound test. APT Sound Testing offer both preconstruction and post construction design solutions to achieve the required sound isolation requirements of Part E of Building Regulations.

This Plate Shows The Main Air Leakage Paths

NoiseFlankingWall

We also offer an acoustic onsite inspection service to ensure that the sound insulation elements are being installed as per manufactures guild lines and the quality of the workmanship is consistent with ‘best practice’ noise control procedures.

You can also undertake you own checks by asking the design consultant i.e. the architect or the builder what steps have been taken to insure your building will be sound adequately sound proofed from your neighbours and from noise intrusion through perimeter envelope from outside the building, after all there isn’t any point your dwelling having high spec acoustic insulation between the inner partitions if sound is transferring through the outer envelope.

 It is never safe to assume because the architect has specified high performance walls, windows and floor/ceiling assemblies that the materials and onsite workmanship will result in compliance with the anticipated results and ultimately a successful sound test. In all these instances successful sound isolation in your home depends on the workmanship during the sound insulation installation phase, the problem is the site installer may know little about noise control techniques unless he is give the right supervision and direction the construction phase.

Part E of Building Regulations stipulates the minimum standards for noise control between residential dwelling units. Upon completion of the building the Building inspection department will need the sound test certification prior to the issue a certificate of occupancy. This shows that the building meets minimum building code standards including sound isolation.

Typical Flanking Sound Transmission Pathways:

  • Dividing Floors – Through Floor and Floor Joist Space (if insulation has not been installed or direct fixing to joists without a drop ceiling below the partition under test)
  • Dividing Ceilings – Above and Through the Ceiling Space (where an adequate acoustic break has not been carried on through the ceiling void)
  • Through Structural Steel (structural steel beams are often a major cause of noise transmission as plasterboard is often fixed directly to the steel without sound breaks)
  • Shared Structural Building Components – Floor Boards, Floor Joists, Continuous Drywall Partitions, Continuous Concrete Floors, and Cement Block Walls.
  • Through Windows (if they are no double glazed or have secondary glazing as a minimum)
  • Fixtures & Outlets – Light Switches, Telephone Outlets, and Recessed Lighting Fixtures (if penetrations have been cut back to back with the opposite dwelling under test)
  • Structural Joints – Perimeter Joints at Wall & Floor, Through Wall & Ceiling Junctures (these should be filled with acoustic mastic)
  • Plumbing Chases – Junctures Between the Walls & Floor Slab Above or at the Exterior Wall Juncture (this should be filed with mortar etc. to add mass to this weakened area)
  • Around the End of the Partition Through the Adjacent Wall (acoustic mastic should be used to seal this junction)

Even if you your wall/floor has been designed so it should provide a high acoustic rating exceeding Part E requirements, this may not be enough. Unfortunately, sound will always find the weakest link, for instance construction workers will usually jack the plasterboard tight to the ceiling in order to achieve a nice tight joint at the ceiling. This often leaves a void or potential noise transference point at the floor/wall junction, which will eventually be covered with a piece of thin skirting board. Failure to fill the joint between the wall and the floor with acoustic mastic can reduce even a 50dB rated wall to under 40dB which will fail the minimum standard of 45dB for sound insulation testing as stipulated within the Building Regulations Part E.

This Video Clearly Shows Sound Flanking Through a Wall

http://www.youtube.com/watch?v=edhLno7LFzY

Often the sound insulation manufacture will provide test lab results for their material. However, you should usually reduce the acoustic target by 4-5dB due to onsite construction. When the construction assembly is tested in the lab it is also certified and the installation techniques are described in detail.  Unfortunately it is not always possible to replicate the exact conditions on the site compared to the ideal conditions within in a lab setting, which is a far more controlled and scrutinised environment. This is the reason why a 5 point difference is allowed between the construction design on paper and the actual on site performance.

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

ROBUST ACOUSTIC DESIGN FOR SUCCESSFUL SOUND TESTING

ROBUST ACOUSTIC DESIGN FOR SUCCESSFUL SOUND TESTING

The first stage of the any project is to undertake robust acoustic design for successful sound testing.  To start this process you need to send  through the design drawings for review, including elevations & sections etc. APT can then review the design detailing to check that the construction details proposed are capable of passing the sound tests. This usually takes place straight after planning has been approved as increased cost savings can be realised at the earliest stage.

ACOUSTIC_DESIGN

APT Sound Testing will evaluate the construction methods and materials specified to ensure that they are capable of meeting the acoustic requirements of Approved document E and subsequently pass the sound testing. The typical areas we check are:

  • The wall and floor design are acoustically robust, to comply with Building Regulations Part E.
  • Check there are no potential flanking points, where isolated partitions are wrongly mechanically fixed together to caused noise bridging.
  • The acoustic treatments for Soil Pipes, Stair Cases Steel Beams etc. to ensure they are acoustically fit for purpose, as these are some of the many areas that get missed that can lead to sound test failure.
  • The Lighting specification to, ensure they are acoustically complaint to the overall design i.e. down lighter design etc.
  • Acoustic floor treatments are compatible with the proposed floor finishes i.e. Carpets, Laminates, Floor Tiles and under floor heating systems.

 If you would like more information in regards to acoustic design and/or 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

 

 

NOISE FLANKING ON YOUR PROJECT

NOISE FLANKING ON YOUR PROJECT

If you fail your Sound Test, you first you need to understand how the sound is travelling into your home. It may be coming directly through the separating partition, i.e. wall or floor or it may be coming along another indirect route – called a flanking path. The most common such flanking path is the inner leaf of an external cavity wall.

http://www.youtube.com/watch?v=edhLno7LFzY

 Problems with airborne and structure borne sound are often associated with direct flanking transmissions through floors and supporting walls and other associated structures. It is essential to establish if your problem is due to direct transmission, flanking transmission or a combination of both so that the most effective remedial treatment can be chosen. If you are unsure where the sound is getting through, then contact us at info@aptsoundtesting.co.uk  as we should be able to identify the worst areas by undertaking sound testing on the problematic partitions.

NoiseFlankingWall

 Unwanted noise travelling along flanking paths makes the building structure vibrate and this causes the sound to radiate into your room. One solution is to build another wall or ceiling in front of the original, but not connected to it (often called an independent wall or ceiling). A basic description of this treatment is given below.

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) and

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.

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

SOUND TESTING – QUESTIONS AND ANSWERS

SOUND TESTING – QUESTIONS AND ANSWERS 

Please find our list of Sound Testing common questions and answers, to help you prepare for the sound testing:

Q. How do I know if my project is ready for a sound insulation test?

  1. A.    All plots should be at least at second fix stage – for further details please refer to our sound testing checklist

Q. Will the sound testing disrupt other site works?

  1. During the sound testing, high levels of noise are generated but in order to make accurate test measurements, relatively quiet conditions are needed. Anyone working in the testing area will have to leave temporarily and any noisy works in the vicinity of the test rooms will need to be halted. The time taken for sound testing varies with the site conditions, but generally a set of tests on houses and flats takes about one to two hours so it’s over fairly quickly.

Q. Do I need to inform my neighbours of the sound testing?

  1. If the building under test is attached in any way to occupied properties then you will need to inform the neighbours. To comply with Part E we need to gain access to the neighbouring properties to undertake the sound test. You will need to ensure that access is provided to the neighbouring properties throughout the sound testing.

Q. Will all internal and external doors and windows need to be fully installed?

A. Yes, all internal and external doors must be fitted and operable prior to the sound testing

Q. What if I only have 110 volt on site?

A. Unfortunately we cannot undertake the testing; we will need 240V to undertake the sound testing.

Q. Can you offer advice on how to pass the sound testing?

  1. Yes, we can offer an acoustic design advice service. If you send through the relevant drawings such as sections, plans etc. during the earlier stages of construction, we can look at your design to check if the design is robust enough to pass Part E and/or there are any junctions or details where ‘noise flanking’ may occur. You can then change your design to reduce the chance of a sound test failure.

Q. Do you have a check-list we can download to help us prepare for the sound test.

A. Yes we do, please click on our sound test checklist; this should help you prepare for the testing.

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

WHAT SOUND LEVELS DO I NEED TO PASS MY SOUND TESTING?

WHAT SOUND LEVELS DO I NEED TO PASS MY SOUND TESTING?

To help you better understand the sound level requirements of Part E of Building Regulations to pass your Sound Testing, we have collated an easy to follow table – shown below.

Table 1a: Dwelling-houses and flats – performance standards for separating walls, separating floors, and stairs that have a separating function.

Airborne sound insulation
DnT,w+Ctr dB
(Minimum Values)

Impact sound insulation
L’nT,w dB
(Maximum Values)

Purpose built
Walls
Floors and Stairs

45
45

N/A
62

Material change of use
Walls
Floors and Stairs


43
43


N/A
64

 

Table 1b: Rooms for residential purposes – performance standards for separating walls, separating floors, and stairs that have a separating function.

Airborne sound insulation
DnT,w+Ctr dB
(Minimum Values)

Impact sound insulation
L’nT,w dB
(Maximum Values)

Purpose built
Walls
Floors and Stairs

43
45


N/A
62

Material change of use
Walls
Floors and Stairs

43
43


N/A
64

Basically, for new build properties you need to achieve 45dB or higher for airborne wall and floor sound tests and 62dB for Impact sound tests. For Converted properties the levels are slightly easier to achieve with 43dB for airborne wall and floor sound testing and 64dB for impact sound testing.

A brief description of the types of sound testing are:

AIRBORNE SOUND TESTS

Airborne sound tests may be required between horizontally and vertically separated pairs of rooms. The sound tests are undertaken by using a sound source, amplifier and loudspeaker to generate a high noise level in one room (the source room). Noise measurements are then taken in both the source and receiver rooms using a prescribed number of source and microphone positions.

The background levels in the receiver room are measured and the reverberation time in the receiver room is also measured. From the results, the airborne sound insulation (DnT,w + Ctr) is calculated and compared to the requirements of Approved Document E.

IMPACT SOUND TESTS

For vertically separated rooms, an Impact sound test may also be required. This sound test is undertaken using a “tapping machine”, (as above) which drops a series of weights onto the floor of the upper room. The noise level in the lower (receiver) room is measured for a prescribed number of source and microphone locations. The background levels in the receiver room are measured and the reverberation time in the receiver room is also measured. From the results, the impact sound insulation (L’nT,w) is calculated and compared to the requirements of Approved Document E.

Impact Sound Testing

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

ACOUSTIC DESIGN CONSULTANCY

Acoustic Design Consultancy 

On all new construction projects its extremely  important that checks are undertaken on the acoustic design from the initial design stage through to completion.

Acoustic Design Advice

We at APT Sound Testing offer a no nonsense professional proactive approach to all aspects of the acoustic design with initial onsite surveys to check the acoustic detailing  is being  installed correctly along with the final sound testing. This ensures your company receives professional advice every step of the way, with an on-going continual consideration of cost.

Acoustic Design & Detailing

We have considerable experience in all matters related to architectural acoustic design and detailing. We can help develop the initial acoustic design of the project from the initial design scheme stage, in particular acoustic isolation, and interior acoustics. We also use the latest Norsonic equipment analysers and sound sources for conventional and binaural acoustic measurements.

Site Survey Visits

We offer site survey visits which allow you (the client) and your contractor to feel confident about the outcome of testing at the end of the build. The site visits let us check that the installation teams are installing the acoustic materials as per manufacturers avoiding crucial onsite mistakes. You can often have a compliant design which still fails due to poor workmanship; the site survey visits negate the risk of sound test failure.

http://www.youtube.com/watch?v=kjTzgxS8HvI

Simple Design Considerations

  • The use of suspended ceilings will help improve the performance of the floor partition.
  • Including a resilient acoustic layer or adopting an “acoustic” flooring system will improve the impact and airborne performance of a floor
  • Avoid using lightweight blocks in the inner envelope construction as sound will travel along these both vertically and horizontally from dwelling to dwelling.

Defect Diagnosis & Remedial Advice

Occasionally we get involved in construction projects that have failed the sound testing, even though we weren’t involved from the beginning. Often it is due to the inclusion of inadequate materials or the exclusion of the necessary materials.

ACOUSTIC_DESIGN

With over 30 years’ experience in building acoustics, we are able to diagnose the reasons for the sound test failure and recommend a cost-effective solution. Often, the reasons for the partition failure are obvious to the test engineer in which case the advice will be minimal and subsequently costs will be minimal. Sometimes, there are more technical issues which require detailed diagnosis and invasive investigation, such as a serious design fault, e.g. the use of lightweight blocks throughout the inner envelope wall on a block of flats.

Whatever the problem we can usually find an acoustic solution that will provide a sufficient acoustic design to satisfy Part E of Building Regulations. If you have a sound test failure then get in touch with us as soon as possible as we should be able to offer you an expedient solution helping you to achieve practical completion in the quickest time possible.

This why we at APT Sound Testing place such emphasis on the process of ‘expert intervention’.

If you would like more information in regards to sound testing or acoustic design, 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