Acoustic Design Considerations

Acoustic Design Considerations

In our experience you need to take into account the acoustic design from the offset of the project, failing to do so usually results in sound test failure; if you do, it usually results in successful pre-completion testing in compliance with Building Regulations Part E.

In many cases, sound test failure can also be down to the poor workmanship rather than the actual design, that is why we offer a full acoustic design package which includes for site survey visits; that way we have the acoustic design and ongoing onsite construction covered, reducing the chance of sound test failure.

ACOUSTIC_DESIGN

There are many Design Considerations, here are a few of the most important:

  • Avoid the use of lightweight blocks in the inner envelope construction as sound will travel both vertically and horizontally from dwelling to dwelling.
  • The use of resilient suspended ceilings will help improve the performance of the floor partition.
  • Ensure all support steels/timbers are carefully boxed out where they travel from flat to flat vertically and horizontally.
  • Use a high quality resilient acoustic membrane on top of the floor to improve the impact performance of a floor.
  • Ensure all penetrations are fully sealed where they terminate through floors and they are adequately boxed with acoustic quilt and two layers of plasterboard.

For peace of mind, many of our clients choose our complete acoustic design package, which contains the following elements:

  • Site Survey Visits – to let us view the existing site construction.
  • Sample Sound Testing – of the existing construction. This offers an accurate overview of the acoustic performance of the existing partitions.
  • Acoustic Design Review – a full design review of the proposed party floors and walls.

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

I Have Passed The Sound Testing So Why Do I Have Squeaking Floors

I Have Passed The Sound Testing So Why Do I Have Squeaking Floors

One potential problem with floors is that they can squeak after they have been installed. This is often down to the fact that Joists are often spaced too far apart which can result in a reduction in floor stiffness and complaints about footstep noise at low frequencies. Over-notching of joists can also lead to a reduction in floor stiffness and also potential squeaking. Although  the projects partitions may have passed impact sound tests, the annoying  squeaking sound may persist due to the extra loads imposed to the floor partition by people walking above.

Noise_Problems_Failed_Sound_Testing

To help with pass the impact sound test timber floors a resilient membrane is often incorporated into the overall floor design. This not only assists impact sound insulation (against footstep noise transference) but also reduces airborne sound transference.

Timber floating floors, must use a flanking strip to isolate the floorboards from the perimeter walls and skirting’s. If flanking strips are not fitted then footstep noise can easily enter the structure via walls etc. and subsequently flank into the adjacent dwellings. In the 1980s, mineral wool was used as a flanking strip but it was difficult to turn round at the floorboard edge. It was also prone to deterioration due to compression and movement under dynamic load. As a direct result of this, 5–10mm polyethylene flanking strips were incorporated into the acoustic design and construction, they are also easier to install and do not degrade over time to the same extent.

There are many reasons why floors may fail the sound testing, such as the use of incorrect mechanical fixing can reduce the insulation performance provided by floating floor treatments and resilient ceiling bars. Using very long screws will lead to bridging of the resilient layers and noise flanking. Inserting pipes or services within a platform floor can reduce the potential acoustic performance if they are not adequately boxed.  The placing pipes or cables under resilient battens can also bridge the resilient layer.

If you require more information about acoustic design and/or sound testing on your project,  please contact us now at info@aptsoundtesting.co.uk or call me direct 07775623464.

Careful Consideration to the Acoustic Design will help you pass your Sound Test

Careful Consideration to the Acoustic Design will help you pass your Sound Test

Careful consideration must be shown to the acoustic design from the start of every conversion project to avoid sound test failures. Most floor designs throughout the 1980s, encompassed the following construction details:

  • Floorboards (18–22mm thick)
  • Gypsum-based board
  • Mineral wool batt (80kg/m3)
  • Sub decking
  • 200-220mm joists
  • 100mm quilt insulation between the joists
  • One/Two layers of gypsum-based board for the ceiling

One the most common constructions used a combination of floorboard, gypsum board and mineral wool batt and was termed a “platform floor”. There is a wide range of batt densities. If the density is too low the floor surface is able to ‘bounce’ and deflect much more easily. If the density is too high then the floor may be too hard and impact sound is able to transmit more easily to the residential dwelling below resulting in sound test failure, so it was very difficult picking the correct materials.

ACOUSTIC_DESIGN

Often, even when resilient battens are used, continuous structural contact along the joist between the floor sub-deck and ceiling provides a strong path for sound transmission. If contact between the ceiling and the joists can be reduced, an increase in airborne and impact performance will be achieved.

One solution is to add another ceiling element to the overall construction. This can provide the extra isolation required to pass the sound testing in London.  This can be achieved by incorporate resilient metal bars which are connected to the underside of the joists and mounted perpendicular (90˚) to the joist direction. If plasterboard has already been tacked to the underside of the joists you can firstly add timber batten and then add the resilient bars, also mounted perpendicular (90˚ to the batten, thereafter 2 x 12.5mm layers of soundboard can be tacked to the underside of the resilient bar. Above the floor a resilient membrane can be used to reduce the chance of impact noise transmitting down to dwelling below.

If you require more information about acoustic design and/or sound testing on your project, please contact us now at info@aptsoundtesting.co.uk or call me direct on 07775623464.

The Different Types of Sound testing in London

This article explains the different types of Sound testing in London

There are two different types of sound testing you need to pass to comply with Building Regulations Part E. This article offers a brief description of both.

Airborne Sound Testing in London

The airborne performance requirements of Part E stipulate that new build properties ned to achieve 45dB and converted properties 43dB. This applies both to party walls and floors between properties. This level is the difference between the source level and the receiver level during London sound tests.

If the source level in one flat is 110dB and the receiver level in the neighbouring flat is 55dB, the level difference (or sound reduction performance) is 55dB. Thereafter the measurement is corrected for several factors such as background noise, room characteristics and frequency weighting, giving the final sound insulation performance value of the tested partition.

sound testing equipment

In this case the higher the number achieved the better the sound insulation performance, whereas Impact testing is the opposite, i.e. the lower the figure the better performance. The measurement is done by using a Norsonic Class 1 Analyser, Amplifier and Speaker (as shown below)

Impact Sound Testing In London

Impact sound testing only applies to party floors and related to the effectiveness of the floor construction in absorbing shock such as footfall noise. The measurement is done by using a Norsonic tapping machine (as shown below). The machine has 5 weights which tapping in regular succession on the tested floor which emulates footfall noise. The noise levels are taken in the receiving room below, which are then measured and averaged for different tapper positions, which then gives the sound reduction rating of the floor. In this case the lower the figure, the better the performance.

Impact Sound Testing

If you have a project that’s needs acoustic design advice or Sound Testing in London, then please contact us at: info@aptsoundtesting.co.uk or phone us directly on 07775623464.

Good Acoustic Design for Sound Testing In London

Good Acoustic Design to Help Pass your Sound Testing In London 

Careful acoustic design consideration should be used from the offset of the project to ensure your project passes the Sound Testing In London, whether it’s new built or a conversion project to meet the required requirements Building Regulations Part E. Tackling these two aspects involves different construction techniques and careful acoustic design detailing. This is good news for the new residents as it proves adequate levels of soundproofing have been incorporated into the buildings design and construction.

In many cases, sound test failure can also be down to the poor workmanship rather than the acoustic design, that is why we offer a full acoustic package which includes for site survey visits; that way we have the acoustic design and onsite construction covered, reducing the chance of sound test failure.

NoiseFlankingWall

We offer an acoustic design package, which contains the following elements:

  • 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.
  • 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.

Acoustic Design Considerations

  • Avoid the use of lightweight blocks in the inner envelope construction as sound will travel both vertically and horizontally from dwelling to dwelling.
  • The use of resilient suspended ceilings will help improve the performance of the floor partition.
  • Ensure all support steels/timbers are carefully boxed out where they travel from flat to flat vertically and horizontally.
  • Use a high quality resilient acoustic membrane on top of the floor to improve the impact performance of a floor.
  • Ensure all penetrations are fully sealed where they terminate through floors and they are adequately boxed with acoustic quilt and two layers of plasterboard.

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

Good Tips on How to Pass Your Sound Testing

Good Tips on How to Pass Your Sound Testing

We thought we would offer some good tips on how to pass your sound testing at the first attempt. The first stage is to ensure that you design the building correctly using the correct acoustic details and materials.

It is also essential that acoustic materials are installed in accordance with manufacturer’s guidelines. There are many potential poor acoustic scenarios that can increase the chance of sound test failure, they are:

  1. Ensure no noisy building work is taking place during the sound testing as excess background noise levels can have adverse effect on the results.
  2. You must fit doors and windows before the test is carried out, to stop noise transference.
  3. Ensure that all doors and windows are shutting properly and rubber seals are properly installed.
  4. Do not directly fix screw plaster board into joists, when using Resilient Bars; ensure that they are fitted in strict accordance with manufacturer’s recommendations.
  5. Do not directly nail or screw through an Acoustic Floor always follow manufactures guidelines and use the correct fixing method.
  6. Ensure you use acoustic insulation with the minimum required density and it fills at least 100mm of the joist void.
  7. Ensure all penetrations such as heating pipes are sealed where they terminate through the floors.
  8. Ensure that acoustic insulation is also packed around service pipe work.
  9. If installing floating screed ensure all isolation layer joints are overlapped and taped.
  10. Ensure that the Acoustic floor is fitted with staggered joints.
  11. Ensure all the Acoustic floor is sealed watertight even around heating pipes.
  12. Ensure that the plasterboard on any walls is complete right down to sub-floor, seal all gaps.
  13. Ensure you use the isolation tape around the wall of each room.
  14. Ensure plasterboard is fitted with staggered layers and all joints sealed.
  15. Ensure all Fireplaces are blocked up with brick or plasterboard.
  16. Ensure that any RSJ’s or supporting steel work is fully insulated and isolated from the main structure.
  17. Ensure all waste pipe service runs are boxed in with insulation and plasterboard.
  18. Do not fit carpets or laminated flooring before you have passed the test.

Acoustic Design Advice

If you need help with sound insulation testing on your project contact us at: info@aptsoundtesting.co.uk or phone us on 07775623464. We have the technical experience to help identify and rectify your soundproofing or noise control problems.

What Types of Sound Testing Do I Need

 

What Types of Sound Testing Do I Need 

Sound Testing needs to be carried out between pairs of rooms separated by party walls or floors. In most cases, the rooms to be sound tested will be the two main habitable rooms – living rooms and bedrooms. All new build dwellings and conversions which were built after this 2004 are required to have 10% of each party wall/floor construction type to be tested.

 

The sound test procedure involves setting up a noise source in a room on one side of the party wall or floor and measuring the noise on both sides of the partition. The three types of Sound Tests usually required – depending on the project configuration) are:

sound testing equipment 

Airborne Wall Tests

Airborne wall sound tests may be required between separate dwellings where a lounge and/or bedroom are positioned against the dividing wall partition. 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.

 

Airborne Floor Tests

For vertically separated dwellings, airborne floor sound testing may be required, where a lounge and/or bedroom sit’s against the dividing floor partition above and/or below a ‘habitable’ room. 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.

 

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.

 

Non-Residential Sound Testing

It is worth noting that sound insulation testing may also be required in non-residential buildings such as schools, hospitals, workplaces, whereas built performance needs to be demonstrated to ensure noise sensitive areas (e.g. classrooms, wards, meeting rooms) are suitably insulated from noisier areas or to comply with BB93 & BREEAM requirements.

 

Sample Sound Testing

If you have an existing building that you are about to convert info flats etc. and need to establish the acoustic performance of the existing partitions, we can undertake sample sound testing on walls and floors to check the sound insulation performance. Thereafter we can forward a targeted acoustic design to comply with Part E of Building Regulations, as well as undertaking the final pre-completion sound testing.

 

All APT’s test engineers carry the latest Norsonic equipment, which are class one rating all of our acoustic testing/sound testing is completed to a strict quality controlled standard. We provide full ISO & UKAS complaint sound testing.

If you would like more information in regards to your air and sound testing please contact us now at info@aptsoundtesting.co.uk or call us on 07775623464

 

controlled standard

Our Pathway to Successful Sound Testing

Our Pathway to Successful Sound Testing

Sound Insulation Site Audits

We can undertake acoustic site audits, to let us view the existing site construction. This allows us to check for potential problematic areas such as the inclusion of lightweight blocks within the existing wall construction. It also lets us check that the installation teams are installing the acoustic materials as per manufacturer’s guidelines, thus avoiding crucial onsite mistakes. In our experience a sound test failure is often due to the poor workmanship rather than the actual design. The site survey visits negate the risk of sound test failure.

We can also undertake sample sound insulation 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 which takes into account the performance of the existing construction.

 Acoustic Design Advice

Acoustic Defect Diagnosis & Remedial Advice

With many 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 the cost for acoustic design advice will be minimal. Sometimes, there are more technical issues which require more detailed diagnosis and invasive investigation, such as large amounts of noise flanking due to serious design faults, e.g. poor material isolation.

Precompletion Sound Testing

To help enforce good acoustic design principles pre-completion sound testing was introduced July 2003, this resulted in all new build properties and conversions which were built after this date are require 10% of each party wall/floor construction type to be tested.

Precompletion Sound Testing is carried out between pairs of rooms separated by party walls or floors. The two ‘habitable’ areas that usually require sound testing are living rooms and bedrooms, although other rooms can be tested if this is not possible, i.e. kitchen to bedroom.

sound testing equipment

If you need sound insulation testing and acoustic design, please don’t hesitate to contact us at info@aptsoundtesting.co.uk  or call me on 07775623464

IMPROVING SOUND INSULATION ON LONDON REFURBISHMENT PROJECTS

IMPROVING SOUND INSULATION ON  LONDON REFURBISHMENT PROJECTS

Many of our new clients ask ‘ how can we improve our sound insulation on our London Refurbishment projects’. One of the main problems is that a large number of the dwellings in London, consist of flats converted from large Victorian houses. Unfortunately at the time of the building conversion, designing for sound insulation was not a high priority 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.

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. By isolating the different materials may not be enough its own and you may need to improve the mass of the partition as well.

Video Showing Main Noise Transference Points Through Existing Partitions.

Improving Existing Floor Partitions

In our experience of undertaking hundreds of sound insulation tests in London, refurbishment projects usually achieve 30-35dB for airborne sound and 70dB for Impact Sound, if the existing construction has not been acoustically upgraded. These figures do not meet the required 43dB & 64dB as stipulated in Part E of Building Regulations. As sound double every 10dB this is a massive failure and acoustic improvements must be made. Many existing construction consist of a similar construction as shown in as detail 1 below.

Detail 1: Existing Floor Partitions Rated At Approx. 30dB

 Failed_sound_Testing_Due_to_existing_floor_Construction_

Acoustic Improvements to Existing Floor Partitions

To reduce airborne and impact sound transmission this usually means adding density and isolation to the floor construction. This can be as simple as adding a drop ceiling consisting of 125mm timber frame. The top of the frame must be a minimum of 25mm below the existing ceiling finish – such as lathe and plaster. Then, to the inside of the timber frame add 100mm of Acoustic Wool and two layers of sound-board tacked to the bottom of the timber frame – all boards to be lapped. This should improve your sound test results by approx. 10-15dB depending on the existing site conditions and quality of the installation. Detail 2 shows this in more detail.

Detail 2: Acoustic Flooring Partition Upgrade

Simple_floor_upgrade_to_Pass_Sound_Testing

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

The Method for Sound Insulation Testing

The Method for Sound Insulation Testing

The method for testing for airborne and impact sound insulation testing methods is clearly presented in BS EN ISO 140-parts 4 & 7: 1998. The sound insulation rating methods that follow are defined in:

 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.

 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 – 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.

sound testing equipment

APT Sound Testing is UKAS accredited to undertake both Sound Insulation Testing and is also accredited to ISO 17025:2005 ‘General requirements for the competence of testing and calibration laboratories’. If you would like more information in regards to sound insulation testing and/or acoustic design, please contact us now at: info@aptsoundtesting.co.uk or call us on 07775623464