The Secret to Successful Sound Testing
There are many considerations to achieving successful sound testing on your development. The main areas that need to be addressed are the dividing wall and flor construction.  When dealing with walls you normally just need to worry about airborne sound; however with walls it’s both airborne and impact sound which can be far more difficult to deal with.

The usual noise problems associated with airborne sound transmission is TV noise, music and speech. This can be dealt with by applying ceiling treatments as well as mass and isolation to the building components. Impact sound (footfall) performance is increased by the used of resilience layers and isolation of components to prevent noise flanking through the partition.

Airborne Sound Testing
For airborne sound testing Building Regulation Part E requires you achieve at least 45dB for new build properties and 43dB for conversion developments, this applies both to party walls and floors between properties. This level is the difference between the source level and the receiver level during sound testing. Therefore, 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.

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. In this case the higher the number the better the sound insulation performance. The measurement is done by using a Class 1 Analyser and the associated equipment.

Impact Sound Testing
For impact sound testing Building Regulation Part E requires you achieve at least 62dB for new build properties and 64dB for conversion developments. Impact insulation performance 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.

Good Acoustic Design
To try and ensure you meet the standards stipulated within Building Regulations Part E, careful consideration should be shown to the acoustic design detailing from the stat of the project. offset. Tackling the acoustic design for both new build and conversion project requires two different construction techniques and acoustic design detailing. With new build properties you have a blank canvas in terms of the overall design whereas with conversions you usually need to work with the existing’ onsite’ construction which can be quite difficult.

We offer an acoustic design package, which contains the following elements:

a.            Sample Sound 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 using the sound insulation performance of the existing construction.

b.            Acoustic Design Review – a full design review of the proposed developments party walls and floors.

c.             Site Survey Visits – to let us view the existing site construction. This allows us to check for potential problematic construction such as inclusion of lightweight blocks in the existing construction. It also lets us check that the installation teams are installing the acoustic materials as per manufacturer’s guidelines.

d.            Final Precompletion Sound Testing in compliance with Building Regulations Part E.

Useful Acoustic Design Considerations

a.            Avoid the use of lightweight blocks in the inner envelope construction and/or stairwell construction etc. as sound will travel both vertically and horizontally from dwelling to dwelling.

b.            The use of resilient suspended ceilings will help improve the performance of the floor partition.

c.             Ensure all support steels/timbers are carefully boxed out where they travel from flat to flat vertically and horizontally.

d.            Use a high quality resilient acoustic membrane on top of the floor to improve the impact performance of a floor.

e.            Ensure all penetrations are fully sealed where they terminate through floors and they are adequately boxed with acoustic quilt and two layers of plasterboard.

In our experience the main 5 considerations when designing for separating walls and floors between dwellings are: If used together or in various combinations they will improve sound insulation properties over a wide range of frequencies. The main factors are:

a.            Mass

b.            Isolation

c.             Absorption

d.            Resilience

e.            Stiffness

If used together or in various combinations they will improve sound insulation properties over a wide range of frequencies and should achieve compliance with Building Regulations Part E.

In our experience if the acoustic design is taken into consideration from the offset of the project, then it usually results in compliance with Building Regulations Part E.  In Some cases sound test failure can also be down to the poor workmanship rather than the acoustic design that is why we offer a full‘4 step’ acoustic package. If you have a project that’s needs acoustic design advice or sound insulation testing, then please visit the APT Sound Testing website  or phone us directly on 07775623464.

Improving Air Tightness in Buildings
Darren Helliwell of APT Sound Testing looks at how construction companies can improve the air tightness of their buildings to ensure they pass their airtightness test first time.

With the Building Regulations and planning requirements and energy assessments pushing buildings towards ever-lower energy use it has become more important than ever to ensure your building is constructed as air tight as possible.

One of the most important steps to improve energy efficiency and occupiers wellbeing in both dwellings and the workplace is by reducing air leakage.

Detail showing a blower fan test equipment

Although the worst allowable air permeability stated in Building Regulations guidance has remained unchanged for some years at 10m3/hr/m2, the actual designed air leakage figure is much lower usually between 3 – 5m3/hr/m2; however, many construction companies are struggling to attain this lower air leakage figure.

If sufficient attention isn’t paid during the design and construction stages of a project, then the lower air leakage rate may be difficult to achieve and there is a much higher risk that the building will fail its airtightness test. Carrying out remediation sealing work and retesting when when a building fails can be a major headache, often leading to delays and cost over-runs.

In our experience, designing and constructing for Airtightness is not rocket science. While many things contribute to a building achieving its airtightness target, one of the biggest factors is usually down to the quality of on-site workmanship.

The key principles of achieving airtightness are as followings:

1. Having a simple air tightness design and construction strategy defined at design stage.
2. Drawings/details clearly identifying the location of the air-line from an early stage (the air-line is basically the elements that serve to provide an airtight envelope around the building).
3. Using building envelope components that are specified as airtight, such as windows, doors, curtain walling, roof lights etc.
4. Using common, easily repeatable details so reduce the chance of buildability issues.
5. Ensuring the building is correctly prepared in line with the air tightness checklists
6. Assigning a single individual to be the air tightness champion with overall responsibility for airtightness during the build and site preparation prior to the test.
7. Communicating the importance or airtightness throughout the entire project team and involving also trades that interface with one another.
8. Making it clear who is responsible for sealing in each instance and produce a sealing closing off sheet, so this process can be accurately monitored

In our experience air leakage commonly occurs at interfaces between construction elements, such as service penetrations and wall-to-roof junctions. Also, air leakage paths may be circuitous, meaning air may travel some distance through the building fabric between the points of entry and exit such as wall cavities etc.

The main areas of Air Leakage:

1. Seal all ducts and penetrations where the main services enter the building – we have encountered many tests where a water pipe duct has been left unsealed underneath kitchen units. After services have been installed in the duct, seal the rest of the duct.
2. Seal behind kitchen and utility room units at the wall/floor junction.
3. Seal all SVP and waste pipe penetrations passing through external walls and ceilings.
4. Make sure that the tops, sides & ends of all pipe/SVP boxing’s are sealed to prevent air leaking into the boxing, and escaping through SVP/waste pipe penetrations. This is particularly important for SVP boxing’s behind kitchen unit. Often the bottom of the SVP boxing is not sealed to the bottom of the floor so the air can escape straight out.
5. Bath and shower tray panels should be fitted and fully sealed.
6. All penetrations through floors & ceilings should be sealed.
7. The boiler flue must be sealed where it penetrates walls or ceilings.
8. Make sure all external door/window seals (if applicable) are installed.
9. In some houses, storage cupboards have been built into the roof space. The doors when closed should seal the room from the roof space. Fit draught excluder if necessary to top, bottom & sides of door/frame.
10. In houses constructed from Timber Frame or where DOT & DAB plasterboard has been fixed to the inside face of block work perimeter walls, the gap.
11. In between the bottom of the plasterboard and floors needs to be sealed at every floor level. Alternatively the gap between the bottom of the skirting board and floor can be sealed with mastic. This prevents air leaking behind the wall board and passing above the ceiling board, into the roof space.

Detail Showing the Main Air Leakage Paths

If you carefully check and prepare your building in-line with our air leakage checklist, it should help you pass your air tightness test at the first attempt. We have helped thousands of individuals and companies achieve their airtightness targets. Using our airtightness know how over many years of air testing and smoke surveys.

Whether you need air tightness test please contact us on 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 visit our website at www.aptsoundtesting.co.uk  for more information on our precompletion testing services.