Sound Test Terminology (1 of 3)

Sound Test Terminology (1 of 3)

Often confusion can arise from the large amount of ‘terms’ used in conjunction with acoustic design and sound insulation testing. To help with this we have made a list of the following terms for clarity – this is the first of three blogs:

Absorption – This is the conversion of sound energy into heat, often by the use of a porous material.

Absorbent Material – This is a material that absorbs sound energy, such as acoustic mineral wool.

Airborne sound – This is sound which is propagated from a noise source through the medium of air. Examples of these are speech and sound from a television

Airborne Sound Transmission – This is direct transmission of airborne sound through walls or floors. When sound energy is created in a room, for instance by conversation, some of the energy is reflected or absorbed by room surfaces but some may set up vibrations in the walls and floor. Depending on both the amount of energy and the type of construction, this can result in sound being transmitted to adjacent parts of the building.

Air Path – This is a void in construction elements, which adversely affects the performance of sound resisting construction. Examples of air paths include incomplete mortar joints, porous building materials, gaps around pipes and shrinkage cracks – this can also effect the air tightness results.

Bonded resilient cover – This is a thin resilient floor covering normally of minimum 3-5mm thickness, which is bonded to the isolated screed surface to reduce impact sound transmission such as footfall noise, however it has a lesser effect when it comes to airborne noise.

Cavity stop – This is a proprietary product or material such as mineral wool (fibre) used to close the gap in a cavity wall.

Composite Resilient Batten – This is composed of a timber batten with a pre-bonded resilient material to provide isolation between the flooring surface layers and floor base.

Cradle/Saddle – This is an intermediate support system (with a resilient layer base, either pre-bonded or already integral) using levelling packer pieces to support a timber batten, isolating it from the floor base.

Acoustic_Ceiling_Upgrade

Decibel (dB) – This is the unit used for different acoustic quantities to indicate the level with respect to a reference level.

Density (kg/m3) – This is the mass per unit volume, expressed in kilograms per cubic metre (kg/m3). Blockwork is commonly referred to by industry in terms of strength (in Newtons). However, it is the density that has the important role in terms of sound insulation.

Direct transmission refers to the path of either airborne or impact sound through elements of construction.

DnT,w – This is the weighted standardized level difference. A single-number quantity (weighted) which characterises the airborne sound insulation between two rooms, in accordance with BS EN ISO 717-1:1997

We hope the above information in regards to Sound Test Terminology has been helpful. If you would like more information in regards to our acoustic design or sound insulation testing services, please contact us at info@aptsoundtesting.co.uk or visit our website at: www.aptsoundtesting.co.uk

GOOD ACOUSTIC DESIGN AND CONSTRUCTION

GOOD ACOUSTIC DESIGN AND CONSTRUCTION

Unfortunately there are many misconceptions when it comes to acoustic design and construction. Unfortunately by simply constructing a good separating wall or floor this may not in itself provide sufficient sound insulation to pass the sound testing for Part E as the junctions of each separating wall and/or floor with other parts of the building are equally as important. There may be other potential issues such as flanking sound transmission that can occur via construction components such as:

  1. the internal partitions
  2. the inner leaf of the external wall
  3. the external wall cavities
  4. the external façade or outer leaf
  5. the roof structure
  6. the foundations.

The overall design and construction system should therefore be considered and not just the separating wall or floor partitions.  Flanking sound transmission may in some cases be the dominant pathway between adjoining dwellings, especially in existing buildings where you are planning to convert offices/large houses into flats where there are large existing penetrations through the floors.

NoiseFlankingWall

Also, 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 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 and undertaken in great 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 sound insulation 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

Broken Down Rating Methods for Sound Testing

Broken Down Rating Methods for Sound Testing 

The sound insulation rating methods that follow are defined in:

Sound insulation testing is usually undertaken near the end of a project to show that the party wall and floor partitions meet the standards shown in Building Regulations Approved Document E.  The method for testing for airborne and impact sound insulation is in full accordance with: the suggested methods presented in BS EN ISO 140-parts 4 & 7: 1998. Sound tests are broken down into various rating methods.

sound testing equipment

The sound insulation rating methods that follow are defined in:

 Rating Method – 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 – 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. Some

acousticians believe that the method is too crude as it only considers the low frequency performance, and because site measurements at low frequencies are prone to difficulties, which can lead to a lack of confidence in the results achieved.

 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.

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

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.

The two types of sound insulation testing through floors.

There are two distinct types of sound insulation testing through floors, they are:

  1. Airborne Noise (for example speech and music)
  2. Impact Noise (for example footsteps directly on the floor above)

In the event of  both types of sound – Airborne & Impact) are emitting excessive noise through the ceiling/floor, then there are some easy installations that should reduce the sound levels and improve your sound test results.

sound testing equipment

We also offer an acoustic design service which helps clients to pass the sound testing upon completion of the acoustic upgrade. By advising on a simple cost effective wall and/or floor upgrade, we are able to forward simple to follow acoustic design reviews, utilising our extensive knowledge of different materials and construction methods. Where our acoustic upgrades have been incorporated into the site construction, all the pre-completion sound tests have passed, ensuring compliance with Part E of Building Regulations.

Pre-completion sound testing has been a mandatory requirement since 2003 and all new build properties and conversions which were built after this date require 10% of each party wall/floor construction type to be tested. In is usual to test between living rooms and bedrooms as these are classed as the two main habitable rooms; however, other rooms can be used if this is not possible such as study’s, kitchens and dining rooms.

We also carry out a large amount of sound tests in council/housing association blocks, where the residents are experiencing excess noise between the dividing wall and floor partitions.

We provide full UKAS accredited air and sound testing in London, using the latest Class 1 equipment, so our clients can be sure that all testing is completed to a strict ISO quality controlled standard

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

Failed Sound Testing in London?

Failed Sound Testing in London?

When a building fails the Part E Sound Test in London it may be down to a problem with the acoustic construction, this may be down to issues such as noise flanking etc.

Ongoing problems with airborne and structure borne sound are often associated with direct noise flanking transmission through floors and supporting walls and other associated structures such as the external envelope. One common cause of noise flanking and failed sound testing is often associated with the inclusion of lightweight blocks within the construction of the building envelope and/or blocked cavities. It all cases it is essential to establish if your problem is due to direct transmission, flanking transmission or a combination of both so that the most cost effective remedial treatment can be chosen.

Sound Testing in London

Unwanted noise travelling along flanking paths will 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, but not connected to it (often called an independent wall or ceiling) so it provides isolation between materials.

One way to reduce the chance of flanking transmission is through careful consideration to the 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 insulation testing. APT Sound Testing offer both preconstruction and post construction design solutions to achieve a successful sound 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. 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. By advising on a simple cost effective wall and/or floor upgrade, we are able to forward simple to follow acoustic design reviews, utilising our extensive knowledge of different materials and construction methods

If you have failed a sound test and need acoustic advice on how to overcome the problem then please contact us at info@aptsoundtesting.co.uk or call me direct 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.

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.