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Sound Testing Consultancy for New Build & Conversion Projects

Author: Apt Sound
by Apt Sound
Posted: Nov 07, 2015

The importance of undertaking acoustic design reviews and on site construction checks cannot be underestimated during the design and construction phase of new and conversion developments. If the project fails the sound testing and prevents the building handover, it can be extremely costly in terms of programme and in some instances can lead to claims by the client. By undertaking careful acoustic design from the initial design stage through to completion APT Sound Testing can help you achieve compliance with Part E of building regulations and reduce the chance of sound testing failure.

We offerseamless acousticpackage which encompasses acoustic design, onsite construction checks and pre-completion sound testing. Using our on-going, proactive approach we ensure clients receive professional acoustic advice every step of the way, with an on-going continual consideration of cost. We can also undertake ‘in house’ UKAS accredited air tightness testing and sound testing in one seamless package, lowering costs and negating potential coordination issues.

In some instances we undertake pre-conversion sample sound tests on existing buildings. In most instances it is best if construction work is delayed until the pre-conversion sound tests have been carried out and evaluated. After the sound tests results are realised we will have a more accurate overview of the existing sound insulation properties and can subsequently undertake a targeted and measured acoustic design, which should save time and money on the acoustic construction.

To enable accuratesample sound testingthe following items need to be in place:

a. All existing doors should be in place

b. All windows should be in place

c. All walls should be in place.

d. All existing floorboards should be left in place.

We then undertake a series of sample airborne sound insulation measurements of the existing walls and floors, as well as impact sound test measurements of the floors to establish the current levels of sound insulation being achieved by the existing dividing partitions.

If the existing wall or floor structures badly fail the sample sound tests, we can prepare an acoustic desktop assessment covering situations where:

a. the performance of the existing structure is below the required standards and the client requires an acoustic design to pass Part E.

b. no testing or working details have been prepared by the client and the acoustic consultant is asked to design and recommend all the separating walls and floors.

c. If the internal walls are constructed out lightweight materials so there is a high chance of noise flanking.

Also, to limit the risk of noise transmission, new build and conversion projects can be carefully planned to take into account the positioning of sensitive rooms in adjoining dwellings. It is important that potentially noisy areas such as kitchens and living rooms should, wherever possible not be located next to quieter areas in the neighbouring dwellings such as bedroom and studies.It is also best to ensure that similar room uses are aligned above and below one another, for example bedrooms should be situated above or below bedrooms and lounges next to lounges.

There are other simple considerations when designing for acoustics, the Cupboards and wardrobes that do not have silent closure mechanisms may lead to complaints about random and sudden noise. Sockets fixed back to back in separating walls may also lead to complaints about noise arising when plugs are inserted and switches are activated. The use of an additional sacrificial wall lining can reduce such noise complaints.

Note that aerial points on or adjacent to separating walls encourage people to place televisions and other entertainment systems against the separating wall and the resultant noise often leads to complaints, if the TV or stereo is simply moved to an internal/external partition this may lower the potential of noise complaints.

With the vast amount equipment and appliances used in today’s kitchens and utility rooms, it is often a cause of noise complaints due to the large amount of noise sources. Wherever possible, sockets for washing machines, dishwashers and fan extract ducts should be located away from the separating wall, especially if they are next to quiet rooms, e.g. studies and bedrooms in the adjoining dwelling. If this cannot be avoided, the separating wall should be designed to provide higher levels of sound insulation via extra wall linings and insulation etc. Plant rooms and lifts can also generate high levels of noise. If the lift has a track system the tracks should be fixed away from the separating wall from adjoining dwellings and extra acoustic upgrades used on the wall adjacent to the lift well.

It is also important to carefully consider floor surface finishes. Hard floor finishes such as wood laminates, tiles and floorboards can significantly increase the level of footstep noise (Impact) in the dwelling below.

The importance of undertaking acoustic design reviews and on site construction checks cannot be underestimated during the design and construction phase of new and conversion developments. If the project fails the sound testing and prevents the building handover, it can be extremely costly in terms of programme and in some instances can lead to claims by the client. By undertaking careful acoustic design from the initial design stage through to completion it greatly reduces the risk of sound testing failure.

Improving Existing Wall and Floor Partitions

Many existing dwellings consist of flats converted from large Victorian/Edwardian 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 wellbeing 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 it’s own and you may need to improve the mass of the partition as well.

Improving Existing Floor Partitions

In our experience - of undertaking thousands of sound tests), refurbishment projects usually achieve 30-35dB for airborne sound and 70dB for Impact Sound if no previous acoustic upgrades have been made to the existing construction. Unfortunately these figures fall far short of the required 43dB & 64dB as stipulated in Part E of Building Regulations. As sound levels double every 10dB, this is a massive failure and acoustic improvements must be made to avoid potential future complaints. A typical existing site construction is shown in as detail 1 below.

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

Acoustic Upgrade for 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. 15dB depending on the existing site conditions and quality of the installation - Detail 2 shows this in more detail.

Detail 2: A Simple Acoustic Flooring Partition Upgrade

Improving Existing Wall Partitions

The standard onsite construction for existing internal walls may be a mixture of 100mm masonry with render applied to either side; or, 100mm timber partition with lathe and plaster to either side. Unfortunately neither of these existing wall constructions will have the acoustic properties to pass Part E in their existing state due to lack of mass and poor isolation values.

Acoustic Upgrade for Wall Partitions

One way to quick and simple way improve the acoustic performance of a the dividing wall partition, is to install a 70mm met-sec partition in front of the existing wall – its usually best to install this in the largest room. Leave approx. 25mm gap between the back of the met-sec and the wall. Then install 50mm acoustic wool to the inside of the met-sec and add two layers of soundboard to the outside of the met-sec frame, ensuring all boards are properly lapped and the perimeter joints are filled with acoustic mastic - Detail 3 shows this in more detail.

Detail 3: A Simple Acoustic Wall Partition Upgrade

Our team of experienced sound test engineers are dedicated to giving our customers the best quality of service and offer acoustic design advice where possible, to help our clients achieve the required acoustic results to pass the sound testing and attain building completion. We can also undertake ‘in house’ UKAS accredited air tightness testing and sound testing in one seamless package, lowering costs and negating coordination issues.

We pride ourselves on offering:

  • UKAS Accredited – we are one of the few companies that is UKAS accredited for both air and sound testing, so you can rest assured our reports will be accepted by building control.
  • One Stop Solution - for Air Tightness & Sound Testing (Building Regulations Parts E & L) to lower costs and negate coordination issues.
  • Fast response - we can usually get to your project within one working week, sometimes faster if it’s an emergency.
  • Acoustic remedial advice - if your development fails any of the tests we can offer a remedial acoustic solution to help you achieve compliance.
  • Quick results - sound testing is arranged around your build schedule and you will receive an immediate indication of test performance on site.
  • Electronic reportage – all or reports are sent electronically so you can send it straight to building control for immediate sign off - no snail mail with us.

Noise Flanking Paths

One of the most common reasons for failed sound tests is due to noise flanking. 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 flanking transmission/s is careful acoustic design at the start of the project. Unfortunately, by simply specifying high performance wall and floor partitions between dwellings 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. 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 construction 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.

Typical Sound Flanking Pathways:

  • Dividing Floor Partitions - 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 Floor/Ceilings Partitions - 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)

If you would like more information in regards to acoustic design and sound testing on your for your development, please contact us at or phone us on: 07775623464.

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Author: Apt Sound

Apt Sound

Member since: Nov 02, 2015
Published articles: 4

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