Excessive Noise Flanking can lead to Sound Test Failure

Excessive Noise Flanking can lead to Sound Test Failure

Noise Flanking is a term used by acoustic engineers to describe where passes sound over the top or under the primary partition separating the two spaces under test. Noise flanking usually appears due to insufficient isolation of materials thus allowing sound to travel through the partition. Unfortunately excessive noise flanking can lead to a sound test failure.

Noise_flanking

One way to reduce the chance of noise flanking transmission is through a careful consideration to the acoustic design from 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, extra care must be shown to the mass, isolation and absorption values of the acoustic construction.

APT Sound Testing offer both preconstruction and post construction ‘remedial’ design solutions to achieve a successful sound insulation testing in-line with Part E of Building Regulations. We also offer onsite inspection services to ensure that the sound insulation elements are being installed as per manufactures guild-lines.

Acoustic_Design_Service

Also, in our experience 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. You should usually reduce the acoustic target by at least 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 and the construction is undertaken within Laboratory conditions, which is a far more controlled and scrutinised environment. Unfortunately, it is not always possible to replicate Laboratory conditions on site due to its more chaotic nature with multiple trades working next to each other. This is the reason why a 5 point difference is allowed between the construction design on paper and the actual on site sound testing performance.

We have undertaken hundreds of acoustic design reviews on all types of projects to help our client achieve compliance with Building regulations Part E, we provide a ‘one stop’ solution for all your acoustic requirements.

If you would like more information in regards to our acoustic design service and/or sound testing service, please follow our blog at: http://soundtestinguk.blogspot.co.uk or contact us at: info@aptsoundtesting.co.uk or call me ‘Darren’ direct on 07775623464.

 

Why Have I Failed my Sound Insulation Test?

Why Have I Failed my Sound Insulation Test?

This is one of the most common questions clients ask when their property has just failed the sound testing. One of the main reasons for acoustic partitions failing the Part E sound test is often down to poor isolation of material/s, which can lead to excessive noise flanking. Noise Flanking is a term used by acoustic engineers to describe where sound passes through an acoustic partition due to the abutment of materials. The noise simply hits the one side of the wall and then travels through the construction via a noise bridge. This can be areas such as the incorrect use of masonry wall ties i.e. solid fishtail ties, used in place of specified acoustic wall ties; if your building suffers from noise flanking it may result in a sound test failure.

Sound_Insulation_Testing_Equipment

Unwanted noise travelling along flanking paths can make the building structure vibrate, which can cause sound to radiate into your room – as shown in the plate below . 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.

Coupled_wall_construction

Noise flanking can also be down to the use of down to the use of lightweight blocks in the construction of the building envelope. 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.

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.

Noise Flanking Can Lead to Sound Test Failure

Noise Flanking Can Lead to Sound Test Failure

Noise flanking can be a huge problem and one of the main causes of excessive sound transmission. If your project fails the sound testing, more often than not noise flanking will be the culprit.

To get an understanding for why the acoustic partitions are performing poorly a detailed diagnosis and invasive investigation, such as the removal of some of the wall and floor partitions will usually need to take place. In many cases a large amount of noise flanking is due to serious design faults such as the use of lightweight blocks in the construction of the walls in an apartment development, this allows the sound to travel along the walls and floors from dwelling to dwelling. In many cases a wall and/or floor partition may have a very good acoustic design and construction; however the partition will still fail as the sound is travelling along a noise flanking path.

Sound_Insulation_Test_London

We often get asked what ate the main reasons noise flanking on new and existing dwellings, in our experience they are:

  1. Where lightweight blocks used in the inner envelope construction. This allows sound to travel along the lightweight blocks both vertically and horizontally from dwelling to dwelling.
  2. Through dividing floors if there is lack of mass or acoustic insulation has not been installed and/or or direct fixing of plasterboard and/or floorboards to joists without using a resilient ceiling construction and/or floating floor.
  3. Through Windows if they are no double glazed or have secondary glazing as a minimum
  4. Through Fixtures & fittings such as light switches, telephone outlets and TV cable ducts where they sit back to back against the adjoining property.
  5. Along structural joints along the perimeter wall and floor joint. These areas should be filled with acoustic mastic)
  6. Structural steels that run through one property to the other without material isolation, i.e. plasterboard is screwed directly to the steel offering little or no noise isolation.

There are many quick and simple solutions to improve the acoustic performance of dividing wall partitions. One of the easiest wall solutions is to install a met-sec partition in front of dividing partition.

If you have a project that’s needs acoustic design advice or needs sound insulation testing then please contact us at: info@aptsoundtesting.co.uk. We should be able to offer you an expedient acoustic solution to help you achieve practical completion.

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.

ACOUSTIC_DESIGN

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.

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.

NoiseFlankingWall

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

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

Dealing With Noise Flanking Issues

Dealing With Noise Flanking Issues 

One of the easiest ways of dealing with noise flanking issues is to use isolation strips around the perimeter of the partitions at the edges of floors and walls. Acoustic sealant should also be incorporated wherever possible. One of the main reasons for flanking sound test failures is when the inner leaf of the perimeter wall is built with light weight blocks. This acts like a large snare drum and the sound simple travels straight up the wall from one flat to the flat above and/or below. Even if you have used a acoustically robust wall and/or floor partition the sound insulation testing may still fail. If you have used lightweight blocks in your onsite construction and the building fails the sound testing you may need to construction independent internal plasterboard lining throughout the inner perimeter wall, this should isolate the lightweight blocks and ensure the flanking path is minimized.

This video shows noise flanking through a window reveal.

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

To reduce the chance of sound insulation test failures, it is imperative that flanking transmission is considered at the design stage and any construction detailing is specified to minimise any potential of noise flanking which will downgrade the acoustic performance. Good detailing at the design stage will minimise this effect and optimise the overall levels of acoustic privacy achieved. If designing for residential units, design advice on flanking details must be followed to maximise the possibility of achieving the specified acoustic performance. It is imperative that the design advice is followed, otherwise the site sound insulation values may not meet the performance criteria required and subsequent expensive remedial treatment may be required.

 If the onsite construction has gaps, cracks or holes it will conduct airborne sounds and can significantly reduce the sound insulation of a construction. For optimum sound insulation a construction must be airtight. Most small gaps can be sealed at the finishing stage using Gyproc jointing compounds. Small gaps or air paths around perimeter Gypframe framework can be sealed with sealant. At the base of the partition, gaps will occur which can be filled with acoustic mastic.

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