Poor Acoustic Design

Poor Acoustic Design 

Sound test failure is often down to poor acoustic design detailing during the design and construction phase of a project.

Sound test failure are often associated with poor acoustic design which allows noise flanking transmission through dividing floor and wall partitions. Unwanted noise travelling along flanking paths can make the building structure vibrate which causes the sound to radiate into your room. One simple cost effective solution is to build another wall or ceiling in front of the original, to offer extra isolation. For this upgrade to work you need to make sure that the independent wall or ceiling is not directly connected to the existing failed partition; so it provides isolation between materials.


One of the main reasons for excessive noise flanking down to the use of lightweight blocks in the construction of the wall construction. Due to the lightweight mas of the inner wall it allows sound to transmit from dwelling to another, both vertically and horizontally. If a building has failed its sound testing, it is essential to establish if the problem is due to direct transmission, flanking transmission or a combination of both so that the most cost and time effective remedial treatment can be designed and applied to the failed partitions.

One way to reduce the chance of sound testing failures due to excessive noise flanking transmission is through a careful consideration to the acoustic design at the start of the project.  Unfortunately, by simply specifying high performance wall and floor partitions, it is no guarantee to adequate sound isolation and successful sound testing.

APT offer preconstruction design advice to help you achieve successful sound testing in London in-line with Building Regulations Part E. We also offer onsite inspection services to ensure that the sound insulation elements are being installed as per manufactures guild-lines, as its not use having a robust design if it not being installed properly on site.

If you require more information in regards to sound testing and/or acoustic design on your project please visit our site at www.aptsoundtesting.co.uk or contact us at info@aptsoundtesting.co.uk, or call me direct on 07775623464.

Noise Flanking Through Steel Columns

Noise Flanking Through Steel Columns.

Unless Steel Columns or beams are isolated from the surrounding wall/floor partition it can lead to noise flanking, particular hollow steel columns. Steel can also provide a strong path for structural impact transmission due to its dense nature.

Pre-conversion sample sound tests should be able to identify whether any columns act as a significant transmission path and whether any acoustic treatment is required to remedy the situation. It may not be necessary to treat the column in all dwellings if flanking is limited, however in many instances the columns will need to be acoustically boxed to prevent sound test failure.


One such acoustic treatment for steel columns or beams would be to construct a free standing metal or timber stud partition around the column, incorporating 50mm insulation quilt and sheeted with two layers of gypsum-based board. Where columns pass through separating floors, as in old bonded warehouses, the junction between column and floor should be well sealed not only for sound insulation but also for fire. The column linings should be double lined with gypsum-based board (minimum mass per unit area 10kg/m2).

Timber beams do not significantly affect the sound insulation performance of a separating floor. However, if a beam has been installed for strengthening, the boxing around the beam may be a single sheet of lightweight board and the board may be fixed directly to the beam resulting in a noise flanking path for airborne and impact sound. This can be resolved by stripping off the boxing, packing any voids with dense mineral wool batt and re-sheeting with two layers of dense gypsum-based sound board.

We hope the above information helps you to understand the potential problems with acoustic design and pre-completion sound testing on your development. If you have a project that’s requires acoustic design advice or sound testing in London, then please contact us at: info@aptsoundtesting.co.uk  or phone us directly on 07775623464.

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.


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.


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.


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 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.

How Many Sound Tests Do I Need On My Project

How Many Sound Tests Do I Need On My Project?

Our clients often ask ‘how many sound tests do I need on my project’. Part E stipulated that one set of sound tests needs to be undertaken for every ten flats or houses, provided the construction system is the same. A set means that the test should include two locations where the party element (wall or floor) is tested. This is equivalent to two individual tests when assessing the performance of a wall this means 2 airborne wall, 2 airborne floor and 2 impact sound tests as a minimum wherever possible. All tests must be undertaken between habitable spaces (e.g. bedrooms, living rooms) and not to or from common spaces such as stairwells and corridors.

Acoustic Design Advice

Approved Document E 2003 also states that a minimum of 10% of all party walls and floors is sound tested for every type of construction or sub-group, this means where there a variations in the construction of the floors and/or walls may occur then further testing may be required. The amount of sound tests required for each type of development is:


On houses two airborne sound insulation tests on a pair of separating walls would be required.


On flats a 6 Pack would normally be required, this would usually comprise of two airborne sound insulation tests on separating walls; two airborne sound insulation tests of separating floors and two impact sound transmission tests of separating floors

Rooms for Residential Purposes:

On student accommodation, hotel rooms & care homes a set of tests would usually comprise of one airborne sound insulation test of a separating wall; one airborne sound insulation test on a separating floor and one impact sound transmission test of a separating floor.

If you are unsure of the amount of sound tests required on your development, please contact us now at: info@aptsoundtesting.co.uk or call me direct on 07775623464.

Minimising Noise Flanking Transmission to Pass Sound Tests

Minimising Noise Flanking Transmission to Pass Sound Testing

One way to reduce the chance of noise flanking transmission/s to pass the sound testing for Part E of Building Regulations is to carefully look at the acoustic details at the design phase of the project, as well as good planning and workmanship thereafter. Unfortunately, by simply specifying high performance wall and floor partitions between dwellings is no guarantee to a sound isolation and subsequently successful sound testing.

Sound travels along the path of least resistance between rooms, usually through any penetrations/air leaks or through rigid and poorly isolated connections in the structure itself, these routes are called noise flanking paths.

  • Wide gaps below doors provide a flanking noise pathway.
  • Air leakage around partition walls at the wall/ceilings junction.
  • Sound leaking through ‘lightweight’ hollow-core doors.
  • Through ductwork penetrations between two rooms or boiler cupboards placed back to back.
  • Fixtures & Outlets – Light Switches, Telephone Outlets, and Recessed Lighting Fixtures (if penetrations have been cut back to back with the opposite dwelling under test)
  • Poor sound isolation between floors, if subfloor wooden planking extend beneath the dividing floor partition and into an  adjoining dwelling this will form a sound flanking pathway.
  • Framing connections that include solid framing members passing between building areas such as oak beams where large old houses have ben subdivided.
  • Poor isolation to partition abutments to adjoining walls, ceilings, floors
  • Service penetrations behind back to back kitchens, such as soil stacks, waste and recessed pipework.
  • 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)
  • 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)
  • 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).
  • Recessed light fixtures that pass through the plasterboard and acoustic insulation.
  • The wrong fixings used during the installation of resilient channel systems, i.e. drywall screws that are too long that penetrate into the ceiling joists.
  • Window noise transmission due to poor performance glass etc.
  • Door noise transmission due to the inclusion of lightweight hollow core doors, with large gaps to the bottom of the door threshold.
  • On bathroom partitions, install drywall all the way to the floor before installing the bath and seal all plumbing penetrations through walls with a flexible sealant.


If the wall/floor partitions have poor isolation and can greatly reduce the effectiveness of soundproofing efforts and can lead to sound test failures. Even if your construction allows for ‘robust’ sound insulation ratings, it will be rendered useless, if sound can pass easily through service penetrations in the walls and floors or through lightweight doors.

APT Sound Testing offers both pre & post construction design solutions to achieve the required sound isolation requirements of Part E of Building Regulations.

We offer an acoustic onsite inspection service to ensure that the sound insulation elements are being installed as per manufactures guide lines and the quality of the workmanship is consistent with ‘best practice’ noise control procedures and we have the technical experience to help identify and rectify your soundproofing or noise flanking problem/s.

If you would like more information in regards to sound testing, please contact us at: info@aptsoundtesting.co.uk or call us direct on 07775623464

Should I inform my Neighbours of the Sound Testing?

Should I inform my Neighbours of the Sound Testing?

Your neighbours will need to be contacted if access is required to their properties to complete the sound testing. Also as the sound levels produced during the test are very high it would be ‘neighbourly’ to inform the residents as they are likely to hear the test. If your project is a new build and/or a change of use and its built onto an existing property then chances are you will be required to undertake an airborne wall test. We recommend that you check this with your local building control officer prior to the testing so you can plan access to the neighbouring properties accordingly.
Can I Observe the Sound Testing?

sound testing equipment

APT Sound Testing will happily give you a brief demonstration and overview of the test, if so required; however, during the actual sound testing, we will need to follow stringent rules which restrict extra personnel within the test areas.
I want peace of mind that I’ll pass the sound testing

Poor Sound test results can occur for many reasons. The most common factor influencing acoustic performance is poor workmanship. Detailing is critical to maximising on site acoustic performance, especially in floor and wall isolation and appropriate party wall and floor construction. If inadequate provision for the isolation of materials is not undertaken

Should I inform my Neighbours of the Sound Testing?