London is a massive city containing over 5 million properties. In this overcrowded environment it is essential that noise transference between properties in kept to an absolute minimum for the occupant’s wellbeing.

We undertake UKAS accredited Part E sound throughout London. We have extensive knowledge regarding the way different materials and construction methods can influence the results of a sound test, to ensure your company achieves complies with Sound Testing Regulations Part E.

Sound Testing Services
Pre completion sound testing under part E has been a mandatory requirement since July 2003. All new build properties and conversions which were built after this date require 10% of each party wall/floor construction type to be tested. Sound Testing is to be carried out between pairs of rooms separated by party walls or floors. In usual circumstances, the room/s to be sound tested will be the living rooms and bedrooms, which are classed as the two main habitable rooms.

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.

Airborne sound tests may also be required between horizontally and vertically separated pairs of rooms. 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.

For vertically separated rooms, an Impact sound test may also be required. This sound test is undertaken using a tapping machine 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 (LnT,w) is calculated and compared to the requirements of Approved Document E.

Our sound test engineers carry all the latest Norsonic equipment, which are class one rating and all of our acoustic testing/sound testing, is completed to a strict quality controlled standard. We provide full UKAS Accredited sound testing.

Pre-completion sound testing is generally carried out at the request of the Building Control Officer. The guidance contained within Approved Document E gives detailed recommendations for the partitions to be tested and for the number of sound tests that should be carried out.

We recommend that the proposed sound testing is agreed in advance with the Building Control Officer prior to the London sound testing.

We can undertake both acoustic airborne sound testing to allow for speech, television etc, and impact sound testing to allow for footfall etc. This is in accordance with the requirements of Approved Document E of The Building Regulations and the relevant European and International standards.

The testing methods for airborne and impact sound insulation testing in London are in full accordance with: the suggested methods presented in BS EN ISO 140-parts 4 and 7: 1998.

If you are in the construction stage of a new project and are not sure if your design will pass the building regulations then contact us at info@airpressuretesting.net and we will check your acoustic design and offer advice (if required) for the wall or/and floor partitions. Alternatively if you require sound testing for your London project please contact APT Sound Testing services today on 01525 303 905.

An Electrical thermal imaging survey is a non-evasive and non-destructive procedure using infrared technology.
Thermographic inspections are the only technique of work that is able to identify any electrical issues like the ones above, in a quick non-disruptive manor or to more precise safety standards. Not only is the thermal imaging fast and safe, it is also a great way to minimise costs as it allows defects to be detected before the equipment fails meaning you don’t need to pay out as much to get it fixed.

As infrared electrical inspections can spot faults before they occur, they can help to extend the life cycle of electrical equipment and identify energy savings for your industry. To try and help clients understand the what involved in a thermal imaging survey, please see our article: A Technical Explanation of Thermal Imaging Surveys.

What’s Involved in an Electrical Thermal Imaging Survey?
Thermal imaging is commonly used for inspections of electrical systems and components in all shapes and sizes. The use of thermography in any electrical installation can help identify faults before they occur, thereby preventing breakdowns, the need for replacement and even fires within the systems and buildings.

An electrical thermal imaging survey using a thermal imaging camera can be used on different types of equipment including:

• Busbar systems
• Distribution boards and fuse boards
• High voltage systems
• Transformers
• Control panels
• Batteries
• UPS systems
• Switchgears and switchboards

Using infrared technology on electrical infrastructure is a renowned method of predictive maintenance and done correctly it can be effective at fault finding prior to equipment failure but it needs to be carried out correctly. Our strict protocols ensure that the faults we document are indeed items that require investigation and possibly remedial work and not simply loaded circuits manifesting temperature.

Thermal imaging can help identify many potential failures such as:

• Poor Connections – Thermal imaging can detect the problems of a poor electrical connection early, the same goes for instances where the electrical cabinets may be overloaded.
• Electrical Leakage – Thermal imaging Surveys are able to find any evidence of a leak happening, in time for you to undertake remedial to preventing possible harm to you and damage to your building/s.
• Insulator Defects – Using thermography you can be protected from the dangerous parts of electricity, ensuring insulators are working properly.
• Internal Fuse Damage – Helps to prevent the risk of a fuse blowing, from an extensive current flowing through it.
• Oxidation of High Voltage Switches – thermography helps highlight potential resistance between connectors, enabling you to finding the problem before it occurs

Our Electrical Inspections involve:

• All panels removed where acceptable, safe to do so and on the Permit to Work
• All electrical equipment/panels/cubicles etc inspected have their own individual trend page which includes a thermogram and digital image, ambient, measured and delta T trending of temperature
• Trending compares data automatically between inspections. Last four thermograms are included on each page and all trend data is captured and displayed in a table and also in graphical format for Measured, Ambient and Delta T (meas/Amb) to allow for condition monitoring of equipment.

Detailed thermal imaging Fault Reports
Our detailed thrmal imaging reports contain fault pages that include a load correction formula is utilised during the inspection. Using component rating, actual load, measured temp and ambient temp, the following values are produced:
• Load corr temp: estimate of component temp if operating at 100% load
• Fault severity based on load corr temp – ref temp (from BS7671)
• Estimation of maximum amps to apply whilst keeping temperature beneath reference temp (BS7671)
• Instant report generation which can be emailed to the client at the end of the inspection

Why use a Level 3 Thermography Engineer on your electrical survey
The importance of using one of our Level 3 trained thermographers cannot be understated as they are trained to be write predictive maintenance and inspection practices and to develop test procedures and ascertain severity criteria. To try and help clients prepare for the thermal imaging survey to their building, we have written the following article: How we carry our thermal Surveys on commercial buildings.

To try and help facility managers with their electrical and mechanical surveys, we have also written the following article: thermal imaging inspections for facilities management. Also, throughout the UK BREEAM projects are becoming more common place.

BREEAM provides extra points to projects that have a BREEAM Thermal survey undertaken, as not many clients are aware of this, we have included more information in our article ‘What is a BREEAM thermal Imaging Survey’. Also to try and help clients prepare for their survey please download our Thermal Imaging Checklist.

APT Sound Testing use the latest high resolution thermal imaging cameras to undertake our Thermographic Surveys throughout London and the Southeast. Thermal imaging is one the quickest and easiest ways to undertake fault diagnosis on your buildings, as thermography can quickly and accurately identify building faults and a easy to follow report, so the defects can be quickly indented and rectified by the contractors.

We pride ourselves on offering a proactive service from start to finish. We have extensive experience of assessing thermal performance on many electrical systems on all types of buildings from commercial launderettes, right through to large power stations.

If you would like more information in regards to Thermography Surveys in London, please contact us now at: info@aptthermography.net or call us direct at: 01525 303 905

Sound Insulation Testing Terminology
Developers and landlords may need to improve sound insulation over a wide range of houses and flats. This may be due to the fact they have just built a new development that requires sound insulation testing under Part E or as part of a general refurbishment program, i.e. changing houses into flats.

Describing Sound Insulation Testing

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:

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.

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

Façade Testing
This Standard – ISO 140-5:1998) specifies the testing methods to evaluate the sound insulation in buildings and building elements for facades. Three rounds of a proficiency testing scheme for airborne sound insulation measurements have been performed according to the methods specified in the standard for a whole facade by using an external loudspeaker as the noise source.

Flanking element (flanking wall)
This is any building element that contributes to the airborne sound or impact transmission between rooms in a building which is not the direct separating element (i.e. not the separating wall or separating floor).

Flanking strip or edge strip
This is a resilient strip using foamed polyethylene normally 5 mm thick, which is located at the perimeter of a floor to isolate the floor boards from the walls and skirtings.

Flanking transmission
This is airborne or impact transmission between rooms that is transmitted via flanking elements and/or flanking elements in conjunction with the main separating elements. An example of a flanking element is the inner leaf of an external wall that connects to the separating ‘core’ of a wall or floor.

Flexible closer
This is a flexible cavity stop or cavity barrier which seals the air path in cavities linking adjoining dwellings.

Floating floor treatment (FFT)
This is a timber floating floor system which may use battens, cradles or platform base, all of which use a resilient layer to provide isolation from the base floor and adjacent wall elements.

Gypsum based plasterboard
This is a dry lining board applied to walls, ceilings and within floating floor treatments which has gypsum content. It may also have fibre reinforcement within the board.

Impact sound
This is sound which is propagated from a noise source through a direct medium. An example of this is footfall on a floor.

Impact sound transmission
This is sound which is spread from an impact noise source in direct contact with a building element.

Isolation
This is a strategy to limit the number and type of rigid connections between elements of construction.

L’nT,w
This is the weighted standardized impact sound pressure level. A single-number quantity (weighted) to characterise the impact sound insulation of floors, in accordance with BS EN ISO 717-2: 1997.

Mass
This is a physical quantity that expresses the amount of matter in a body. Walls and floors may be described in terms of the surface density (mass per unit area, kg/m2) of the wall face or the floor surface, which is the sum of the surface densities of each component of the construction. The density of materials is expressed as mass per unit volume, kg/m3, which can be provided via the core structure and linings such as in-situ concrete or solid dense block walls.

Mass per unit area (or surface density)
This is is expressed in terms of kilograms per square metre (kg/m2). This is often used to describe boards, panels, flooring and dry linings (see gypsum based board).

Resilience
This can reduce structural vibration transmission and still maintain material performance and overall dimensions, examples include floating floor treatments such as resilient battens or cradles, or resilient ceiling bars.

Resilient ceiling bars
This acoustic solution is generally metal based and vary in thickness from 11 mm to 30 mm. They are mounted perpendicular to the joist span direction and can increase both airborne and impact sound insulation. Care should be taken to ensure that the ceiling board fixings into the resilient bar do not come into contact with the joists and reduce the potential performance.

Resilient noggin
This is a small section of resilient ceiling bar which is used to assist in bracing non load bearing partitions.

Rw
This is a single-number quantity (weighted) which characterises the airborne sound insulation of a building element from measurements undertaken in a laboratory, in accordance with BS EN ISO 717-1: 1997

Sound Insulation Testing
Sound Insulation Testing is required near the end of a development to show that the performance of the party wall and floor partitions meet the standards as stipulated in Building Regulations Approved Document E. The testing methods for airborne and impact sound insulation is in full accordance with the suggested methods presented in BS EN ISO 140-parts 4 & 7: 1998.

Stiffness
This is can improve low frequency sound insulation, for example in floors, by reducing the potential for deflection or movement of the primary structure, therefore the correct spacing and depth of joists is important. If you have a project that requires acoustic design and/or sound insulation testing please let us know. APT Sound Testing will ensure you will have direct contact with the allocated acoustician from the start of the process, through to the successful completion of the sound insulation testing. 

If you would like more information in regards to acoustic services, please contact us at info@aptsoundtesting.co.uk, call 01525 303905 or visit our website at: www.aptsoundtesting.co.uk    

Air tightness testing, also known as blower door testing, is the process of measuring the amount of air leakage from a building through the building envelope. To try and help our clients better understand and prepare for their air tightness testing, we have tried to explain and answer our customer’s most common questions. For more information on our air tightness testing services you can also visit our Services Page.

What is Air Tightness Testing for Building Regulations?

Air testing is mandatory in the United Kingdom and is governed by Part L of the Building Regulations, this split into two parts; for domestic properties Part L1A should be used and for commercial properties Part L2A should be referenced.

Building Regulations Part L states air tightness testing should be carried to check the air leakage that occurs through a buildings envelope. The air leakage test checks the amount of air that escapes through gaps or air leakage paths through the building fabric. If the building is more air tight, less energy will be being needlessly lost, thus lowering the carbon emissions of the building. Air testing also shows how efficient a building is at retaining conditioned air which will also put less straight on your mechanical and ventilation system. Failing to maintain adequate air tightness can lead to up to 50% of heat loss from within a building to the outside atmosphere.

What air leakage target do I need to achieve?

Most new dwellings and commercial buildings need to achieve an air leakage of 3m3/hr/m2 to 5m3/hm2, this rate would usually be acceptable by building control and your SAP assessor as an acceptable result, although you need to check each your designed SAP assessment as there may be items within your buildings design that that may affect this figure.

How long does the air test take?

Most air tightness tests can be completed in 1-2 hours if they pass straight away; however, tests can take much longer if they initially fail. It usually speeds up the process if customs prepare their buildings in-line with our air tightness checklist as its means we can start the testing as soon as we arrive on site instead of waiting for the client to tape up areas, or make upgrades to the building envelope.  We also offer a smoke testing service to locate the air leakage paths within a building envelope which can also take extra time; however this often allows our clients to seal and pass their building at the first attempt even if their building initially fails the air test.

How do you undertake an air tightness test?

The air tightness test is undertaken in-line with Building Regulations Part L1 & L2 and ATTMA TS1 & TS2. Basically we measure the pressure differential across the envelope of the building by means of the temporarily installation of a large fan inside a door panel. Thereafter, a range of static pressures and environmental readings are taken. The fan is switched on and the air pressure in the property is gradually increased or decreased and the differential pressure is recorded at each step, usually from 25 Pa to 70 Pa. The total air flow required to achieve a pressure differential of 50 Pa is calculated and divided by the total building envelope area to provide the leakage rate in m3/h.m2@50Pa.

How do I prepare my building for the air test?

The more complete you’re building the more chance you have of passing the air tightness test at the first attempt. We send our and air test checklist with every quotation to help our client prepare for the testing. It is our aim to help clients pass their air test at the first attempt.

Basically you prepare the building in-line with our checklists and the items below, you will generally have a much better chance of passing the testing at the first attempt.

1. The building envelope should be fully complete; this includes walls, floors and ceilings.
2. All doors and windows must be fully fitted and able to shut tightly against their seals.
3. All electric fittings must be installed and functional.
4. All mechanical fittings must be installed and functional.
5. Gaps within walls and floors must be sealed.
6. All service penetrations must be fully sealed through the building envelope. 
7. Bathrooms and kitchens must be fully fitted and all service penetrations sealed.
8. All mechanical ventilation turned off with grilles sealed.
9. All trickle vents to windows and doors must be sealed.
10. All fireplaces must be sealed.
11. Ensure water is present in soil pipes.
12. 240v power must be available on site.

Whether you need air tightness test please contact us on 01525 303 905 or email us at info@aptsoundtesting.co.uk  to obtain a no obligation quote. If you need more information on how to prepare your building for the air test please download our air tightness testing checklist. 

Alternately, please call visit our website at www.aptsoundtesting.co.uk, for more information on our precompletion testing services

Volatile organic compounds (VOCs) are gases that are given off by many indoor sources. Concentrations of most volatile organic compounds are higher in indoor air than outdoor air and can lead to health concerns. That’s why indoor air quality testing for AOVs is very important.

What are VOCs and where do they come from?
Formaldehyde, is a very common VOC, it is a colourless gas with an acrid (sharp and bitter) smell. It is most common in building materials such as plywood, particleboard, and construction glues. Formaldehyde can also be found in curtains, drapes, and fabrics and in certain types of foam insulation, your lounge settees are one of the most common culprits.

Other sources of VOCs include the burning of fuels such as gas, oil, wood, coal, kerosene and tobacco products. Interestingly, VOCs can also come from personal care products such as hairspray, perfumes, cleaning agents, paints, lacquers, and varnishes.

VOCs can be much higher when a product is new and will usually be released from products during use and even in storage, that’s why indoor air quality testing is usually carried out to new and newly refurbished buildings prior to handover, which can also lead to extra BREEAM credits. However, the number of VOCs emitted from products tends to decrease as the product ages.

What health concerns are associated with VOCs?
Volatile organic compounds (VOCs) include many chemicals that can cause shortness of breath, fatigue, headaches, nausea, dizziness and skin problems as well as eye, nose and throat irritation. Higher concentrations may be even more problematic causing irritation of the lungs, as well as damage to the liver, kidney, or central nervous system. Long-term exposure may also cause permanent damage to the liver, kidneys and/or central nervous system.

Some Volatile organic compounds are suspected of causing cancer to humans. The health effects caused by VOCs depend on the concentration and length of exposure to the chemicals, so minimising the VOC levels is critical in new and refurbished buildings. By undertaking VOC air quality testing, we can quickly establish the levels in your building and let you know if they are higher than what’s recommended.

The Indoor Air Quality Testing Experts
APT Sound Testing has a large amount of experience in the provision of BREEAM Indoor Air Quality Testing services. This ensures we are able to address all elements of Hea 02 ‘Indoor Air Quality. We have supported a wide range of BREEAM projects within the commercial and industrial sectors. These have included hospitals, health centres, laboratories.

Please get in touch with a member of our engineering team today at info@aptsoundtesting.co.uk or 01525 303905 to find out more about how we can help with the indoor air quality testing aspect of your BREEAM development or visit our case studies to review recently completed projects such as The Annexe (Imperial War Museum) and The Heals Building in Central London.

If you fail the Part E sound testing, you will be required to carry out remedial works to ensure the development meets the relevant performance requirements of Approved Document E.

If you fail the sound test there is no reason to panic as APT Sound Testing can advise you on a cost effective solution to pass the testing. The original fees associated with the preliminary sound testing; do not cover the work involved in providing acoustic remedial design advice or repeat compliance sound testing.

Building Control may also request you test further examples of the construction elsewhere on the development, in order to restore confidence and/or highlight the extent of the problem; this is so they ascertain if the failure is an isolated problem or generic throughout the site.  In our experience several points of failure can occur within a project. Although, it less likely that a sound test failure will occur where robust construction and workmanship has been maintained, unfortunately noise flanking on walls and floors may still result in acoustic failure.

In our experience some of the most common mistakes during the construction phase are as follows:

Using lightweight blocks in the inner envelope construction as sound travels along the light block-work both vertically and horizontally from dwelling to dwelling.

Not incorporating a high quality resilient acoustic membrane on top of the floor to improve the impact performance of a floor.

Ensuring all penetration’s are fully sealed where they terminate through floors and they are adequately boxed with acoustic quilt and two layers of plasterboard.

Reducing the Risk of Sound Testing Failure
To reduce the chance of sound testing failure, 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.

How Much Will My Sound Test Cost?
This depends upon the size of the development and the number of tests involved. APT Sound Testing will provide a free quotation and informative checklist to help you prepare for the testing within 24 hours of your enquiry. Our quote will include for the sound testing and the report with no hidden extras.

What are Robust Details?
From the 1st July 2004, Robust Details may be used to eliminate the need for end of build pre-completion testing. Robust Details are high performance constructions that are capable of providing consistently good sound insulation but do require that the design is registered with, and approved by, Robust Details Ltd.  The specific details in the RDL handbook must be followed explicitly and each plot formally ‘registered’ with RDL before building commences. Robust Details registration cannot be used in conversion projects and so pre-completion testing must be undertaken in these circumstances.

As the specific details in the Robust Details scheme may not allow for flexibility in the design of a development or may not prove cost effective, pre-completion sound testing may still prove a more suitable and effective route to demonstrate compliance with Part E of Building Regulations.

Acoustic Credits for BREEAM
Under BREEAM Hea 05 and Pol 05 it is possible to get credits for acoustic performance. Pre-completion sound testing can be used to verify performance and achieve BREEAM credits. APT Sound Testing  can advise you as to the requirements of BREEAM.

Contact APT Sound Testing
If you would like more information in regards to sound testing or acoustic design, please follow our blog at: http://soundtestinguk.blogspot.co.uk/, or contact us on 0777 5623464 or visit our website at: www.aptsoundtesting.co.uk  

The need to carry out sound insulation testing to assess and report the acoustic performance of dividing partitions between dwellings has become increasingly important in order to demonstrate that a building’s intended performance is achieved when constructed.

Poor design detailing and/or onsite construction can have a significant impact on the overall performance of building elements and the building as a whole. Post completion sound testing provides greater certainty that designed performances are actually being achieved in compliance with Approved Document E.

Precompletion Sound Testing is now an integral part of supporting the completion certificate process throughout the UK and Ireland. In order to ensure that testing is undertaken within a robust regime which controls the reliability of test results, government guidance is in place which describes restrictions on those who should carry out sound testing and reportage.

Approved Document E states a set of sound tests should be carried out for every ten dwellings (houses, flats or rooms for residential purposes). However, if the development has several different construction types, you may need to carry out further tests for each type of construction.

For houses this usually means you are required to undertake 2 airborne wall sound tests (up to 10 houses) to the dividing walls. For flats you will be usually be required to undertake 2 airborne wall, 2 airborne floor and 2 impact floor tests (up to 10 Flats). When we undertake a fee proposal for clients, we always include a full testing schedule so it can be submitted to building control for their approval prior to the test date.  

One of the stipulations of Approved Document E is that the testing company needs to be UKAS accredited, this is covered under the Resistance to the passage of sound: Approved Document E [ADE] it goes on to state that “The person carrying out the building work should arrange for sound insulation testing to be carried out by a test body with appropriate third party accreditation” and is downloadable at: https://www.gov.uk/government/publications/resistance-to-sound-approved-document-e.

APT Sound Testing is UKAS accredited to carry out sound insulation testing and is laboratory and as a result our reports will be accepted by building control – here is a link to our UKAS Sound Testing Accreditation: https://www.ukas.com/wp-content/uploads/schedule_uploads/00002/4340Testing%20Multiple.pdf

For future note we are also UKAS accredited to carry out Air Tightness Testing – here is a link to our UKAS Air Tightness Accreditation: https://www.ukas.com/wp-content/uploads/schedule_uploads/00002/4340Testing%20Multiple.pdf

If you would like more information on our sound testing service and/or other services please contact us now at: info@aptsoundtesting.co.uk or visit our website at www.aptsoundtesting.co.uk.

Alternately, if you would like more information on how to prepare for your sound insulation testing please download our sound test checklist.

Airborne and Impact Sound is transmitted through most walls and floors by setting the entire structure into vibration. This vibration generates new sound waves of reduced intensity on the other side. The passage of sound into one room of a building from a source located in another room or outside the building is termed ”sound transmission”. 

Understanding Sound Testing
Sound transmission loss or Sound Reduction Index, R dB, is a measure of the effectiveness of a wall, floor, door, or another barrier in restricting the passage of sound. The sound transmission loss varies with frequency and the loss is usually greater at higher frequencies. The unit of measure of sound transmission loss is the decibel (dB). The higher the transmission loss of a wall, the better it functions as a barrier to the passage of unwanted noise across the dividing (acoustic) partitions.

Approved Document E stipulates that there are two types of sound insulation in buildings: airborne and impact. Airborne sound insulation is used when the sound produced directly into the air is insulated and it is determined by using the sound reduction index. Impact sound insulation is used for floating floors and it is determined by the sound pressure level in the adjacent room below.

A sound insulation test of a separating partition will be considered as a pass if the airborne sound insulation is equal to or greater than the DnT,w + Ctr value shown for the appropriate dwelling in the table, for airborne testing in new builds properties a figure of 45dB or greater is required and for Impact testing 62dB and below. For conversion properties a figure of 43dB or greater is required and for Impact testing 64dB and below.

What is DnT,w

DnT,w is an in-situ measured performance parameter that demonstrates the level of resistance to sound transmission between two adjacent spaces, such as flats or houses. The measurement will include both direct sound transmission and flanking sound transmission of the construction. Flanking transmission is the effect of sound travelling through the building and may be particularly evident where beams and joists bridge a common partition or along poorly isolated lightweight wall constructions.

The DnT,w of a separating wall or floor will typically be of the order 5 to 7 dB lower than the manufacturers specified Rw (single figure quantity of sound insulation) for the single element, due principally to the contribution from flanking sound transmission around the element when it is built on site – this should always be accounted for in the initial acoustic design.

What is Ctr

Ctr is the spectrum adaption term. It is a correction attributed to the sound insulation quantity to account for urban traffic noise.

What is L’nT,w

L’nT,w is an in-situ measured performance parameter that demonstrates the level of resistance to impact sound transmission between floors. The impact measurement includes both direct sound transmission and flanking sound transmission.

Weighted Sound Reduction Index Rw

When specifying the acoustic performance of an acoustic partition in a more general manner, it can be useful to describe the sound insulation by a single number. The weighted sound reduction index, Rw , is a rating method given in EN ISO 717-1. This standard fits a standard reference curve to the measured sound reduction index curve.

Within the EN ISO 717-1 standard, a rating method is also given where the Rw value is completed by two C-terms which are applied to two models of the noise spectra for various types of noise. These two terms, Rw + C and Rw + Ctr, also include the frequency range 100 – 3150 Hz but can be extended to 50 – 5000 Hz. As industrial and traffic noise often have high sound levels which are also below 100 Hz, it is recommended that the extended frequency area is used.

The summary value, Rw + C, gives the reduction value in dBA for a spectrum with a level that is equally high in all third-octave bands. This can be used for:

•             Highway road traffic travelling at speeds in excess of 80 km/h

•             Factories emitting mainly medium and high-frequency noise

•             Living activities (talking, music, radio, TV)

•             Railway traffic at medium and high speed

•             Jet aircraft at a short distance

The summary value Rw + Ctr also gives the reduction value in dBA, spectrum with low-frequency dominance such as:

•             Disco music

•             Urban road traffic

•             Railway traffic at low speeds

•             Factories emitting mainly low and medium-frequency noise

Both the impact and airborne insulation performance of floors and walls should be carefully considered from the start of the project to ensure that the minimum performance requirements for new and converted developments are met in line with Approved Document E

If you would like more information in regard to our sound testing and/or noise survey services, please contact us now at info@aptsoundtesting.co.uk or call 01525 303 905 today.

Many of the dwellings in London and other UK Cities consist of flats that have been converted from large Victorian or Georgian houses, or more recently office blocks. Unfortunately designing for sound insulation is not always shown the highest priority so many converted 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.

APT Sound Testing have helped many of our clients achieve compliance with Part E, by undertaking some simple steps. We can undertake an initial sample sound test of the existing wall and floor construction to ascertain the existing sound insulation levels. Once we have established the sound levels for the existing construction, we can then look at the extent of the acoustic upgrades to attain Part E Compliance. This is much more effective than just forwarding an acoustic design that may be to excessive and expensive, especially if the existing floor and/or wall only needs to improve by a minimal amount such as 1-3dB. By having the existing sound levels of the partitions we can recommend targeted, acoustic upgrades to comply with Building Regulations Part E. 

The sound insulation levels required to pass Part E for refurbishment projects are less stringent than new build projects. Instead of 45dB for airborne its 43dB (2 dB less), and for instead of 62dB for Impact Sound Testing its 64dB on new build (2 dB more).

In our experience, refurbishment projects usually achieve 30-35dB for airborne sound and 70dB for Impact Sound during the sample sound test – 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 major acoustic improvements must be made. Many existing constructions consists of similar construction as shown in as detail 1 below.

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

Improving Wall and Floor Partitions

There are ways you can improve the airborne and impact performance by improving the wall/floor partition’s ability to reduce the amount of sound transmission from one side of a construction element to the other. However; by isolating the different materials may not be enough its own and you may need to improve the mass of the partition as well.

Existing Floor Partitions

In our experience, 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.

Improving Existing Floor Partitions

To reduce airborne and impact sound transmission 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.

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 usually have the acoustic properties to pass Part E in their existing state due to lack of mass and poor isolation values. 

Improving Wall Partitions

One quick and simple way to improve the acoustic performance of the dividing wall partition is to install a 70mm met-sec partition in front of the existing wall – it’s usually best to install this in the largest room backing onto the dividing partition. 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 the soundboard to the outside of the met-sec frame, ensuring all boards are properly lapped and the perimeter joints are filled with acoustic mastic.

Taking the above into account is it essential that good acoustic design is addressed right from the start of the refurbishment project, so it prevents delays in handover, i.e. to prevent the dwelling failing the sound testing at building control signoff stage.– a common problem.

If you would like advice on your acoustic design or require sound insulation testing in London, please contact us now on 01525 303 905 or contact us at info@aptsoundtesting.co.uk.