Month: June 2022

Complying with Stringent Air Test Targets

Complying with Stringent Air Test Targets

Complying with Stringent Air Test Targets
For many residential dwellings the new air leakage rate will drop to  5m3/hr/m2, however if you only undertake air testing to a sample of dwellings then you need to better this target by 2m3/hr/m2 resulting in an air leakage rate of 3m3/hr/m2.  This more stringent target, although difficult to achieve can be passed at the first attempt; although, careful consideration must be shown to the air tightness design and ‘on site construction’ from the start of the project.

Once of the main reasons of air tightness test failures, is not knowing where the air seal line is. It is usually the inner envelope of the building; however, sometimes it may be a new extension to the building so the air seal line may actually be an existing internal wall. If you are unsure about the air seal line on your building/s its best to ask your architect and/or contact us.

We offer the following air tightness services to help you

•           Air Tightness design reviews – to ensure the air seal line has been adequately designed. 

•           Air Tightness site visits – to ensure the onsite construction is correct.

•           The air tightness test

•           Dual smoke survey – in the event of an air test failure to highlight the air leakage paths. 

Good Tips for Air Tightness Design

Good detailing and materials selection needs to be high on the list of priorities for all members of the team, right from the start of the project to ensure that:

•           The airtightness barrier layer is identified

•           The correct products are used where required

•           The relevant areas are monitored throughout the construction phase

The use of certain types of ‘temporary’ products such as adhesive tapes or expanding foam should be avoided since these do not perform over the life of the building.

Tips for Walls

Dry-Lining (dot & dab) walls
Ensure that the external walls are completed and fully sealed prior to constructing internal stud partitions over them. The gap at the bottom of the plasterboard should be sealed to prevent air loss behind the board and into ceiling/roof spaces. Alternatively the gap between the bottom of skirting boards and the floor can be sealed. Avoid/minimise service outlets such as sockets, data outlets etc. in the dry lining of external walls as they are rarely well sealed.

Standard block-work is not impermeable. The block density and standard of mortar joints have a significant impact on the overall permeability of the construction. Full mortar joints are preferable. Painting block-work reduces the permeability and two coats of emulsion can make a significant improvement. All gaps between block work and intermediate floors, roof members, windows/doors, steel columns, etc. should be sealed.

Timber Frame/Metal Studding
Ensure that the external walls are completed and fully sealed prior to springing internal stud partitions from them. Avoid/minimise service outlets such as sockets, data outlets etc in the dry lining of external walls as they are rarely well sealed. Like the dot and dab walls, the gap at the bottom of the plasterboard should be sealed to prevent air loss behind the board and into ceiling/roof spaces.

Tips for Floor Constructions

Cast In situ Concrete Slab
This type of floor usually provides the best type of airtight seal, since the concrete fills any voids, both horizontally and vertically.

Pre-cast Hollow Concrete Floor Planks
The hollow core of this type of floor can allow air to track horizontally and end up outside the airtight layer of a cavity wall. The problems are made worse with drainage and service penetrations, which if poorly sealed allows air to enter the hollow core and escape. Care should be taken to ensure all penetrations are sealed properly. it is also prudent to seal  the ends of the concrete planks.

Beam and Block Floors
This type of floor construction can lead to similar problems to those described for the pre cast planks above.

Timber Floors:
Any penetrations passing through the top of the floor layer or the underside layer of (e.g. radiator pipes, waste pipes, boiler flues) need to be sealed where they pass through the timber/plasterboard layer

Tips for Ceiling Constructions

Plasterboard & Lay in Grid Ceilings
Where roof/ceiling voids exist, lay in type false/suspended ceilings do not form an airtight barrier layer. Plasterboard type ceilings – if plastered and the edges sealed are significantly better than other types of lay in ceilings.

Tips for Doors And Windows 

Doors & Windows

Door and window frames need to be sealed to the internal air tight barrier and not just sealed to the external façade. Window sills are often an area which performs particularly poorly and should be fitted after the cavity has been sealed using an appropriate cavity closer. For Windows & doors, refer to BS EN 12207 Windows & Doors Air Permeability Classification & BS EN 6375 – Use class 4 or better 3m3/(h.m2)@ 100Pa. Lift shafts have a permanent vent to outside at the head of the shaft and should be fitted with effective doors seals at each landing. Any floor or ceiling voids adjacent to the shaft should also be adequately sealed to prevent leakage.

Tips for Mechanical & Electrical Systems:

The airtight barrier generally steps inside the building to include plant rooms as part of the external space. The plant room partition walls and sometimes service riser walls therefore require careful sealing around all mechanical and electrical service penetrations. Avoid using conventional fire stopping materials to form the airtight barrier, as these are seldom suitable. Particular care is needed to fill voids inside the electrical service trunking.

Tips for Sanitary Services

Careful consideration should be given to sealing the underside of all wall mounted toilets as the underside of the toilets are susceptible to air leakage where the SVP terminates through the wall. All drainage traps including floor gullies and air handling plant condensate traps should be filled with water prior to the air test.

Whether you need a full on-going air tightness design/consultancy service, or a simple air test, we have the knowledge and experience to ensure your building passes first time.

If you are unsure of the air tightness test service you require, please call us on 01525 303905 or visit website today and we will guide you through the process, ensuring that you receive the right level of advice at the right time.

Sound Insulation Testing & Consultancy

Sound Insulation Testing & Consultancy

Sound Insulation Testing & Consultancy
We offer a no nonsense professional proactive approach to acoustic design, onsite construction checks and pre-completion sound testing. Using our on-going, proactive approach we ensure clients receive professional advice every step of the way, with an on-going continual consideration of cost.

The importance of undertaking design reviews and on site construction checks is often forgotten resulting in sound test failures at the end of the project prior to building control signoff. This can be extremely costly in terms of programme and possible 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.

Acoustic Design
We have considerable experience in all matters related to architectural acoustic design and detailing. We can help develop the initial acoustic design of the project from the initial design scheme stage. Our approach is robust and does not leave any room for errors using our In-depth knowledge of acoustic materials, construction systems and Regulations we can provide the following:

>>> Provision of cost-effective and practical acoustic solutions

>>> Thorough understanding of the desired character of the space

It is essential that strong communication among the members of the design team members is essential, to facilitate this we can undertake design meetings and site inspections to finalise the acoustic solutions in full accordance with the project’s aims.

Specification of External Building Fabric and including walls, doors and windows in order to minimise noise break-in, or break-out for privacy and overall acoustic quality within dwellings.

Acoustic testing of existing wall façades to ISO 140-5, to check the existing sound levels so new targeted wall upgrades can be specified.

Acoustic Investigation and design of rooms/spaces for a wide range of environments such as schools, offices and commercial spaces.

Site Visits
We offer a site survey service which allows our clients to feel confident about the outcome of their sound testing at the end of the build. The site visits let us check that the installation teams are installing the acoustic materials as per manufacturers avoiding crucial onsite mistakes. You can often have a compliant design which still fails due to poor workmanship; the site survey visits negate the risk of sound testing failure.

A Few Simple Design Considerations
The use of suspended ceilings will help improve the performance of the floor partition. Including a resilient acoustic layer or adopting an “acoustic” flooring system will improve the impact and airborne performance of a floor

Avoid using lightweight blocks in the inner envelope construction as sound will travel along these both vertically and horizontally from dwelling to dwelling.

Use carpet in hallways/corridors to lower reverberation levels.

Key considerations of acoustic design are:

>>> Careful design consideration for all separating walls and floors

>>> Careful design consideration for all internal wall and floor performance

>>> Careful design consideration for the external/internal building façade.

>>> The specification of glazing/curtain walling

>>> The specification of doors

>>> The specification of ventilation

>>> The building/s orientation and layout

>>> Careful design consideration if using lightweight external walls and roofs

>>> Careful design consideration for all internal wall and floor performance

>>> Careful design consideration to reverberation control and room acoustics

>>> Acoustic screening from external noise such as fencing etc.

>>> Acoustic protection from plant rooms, communal areas etc.

>>> Noise exposure of outdoor spaces such as gardens, balconies.

Defect Diagnosis & Remedial Advice
We occasionally get involved with projects that have failed the sound testing – even though we weren’t initially involved with the project. Often it is due to the inclusion of inadequate materials or robust acoustic design and isolation of materials.

Using our considerable experience in building acoustics, we are able to diagnose the reasons for potential the sound testing failure and recommend a cost-effective solution. Often, the reasons for the partition failure are obvious to the test engineer in which case the advice will be minimal and subsequent design advice costs will be minimal; however sometimes, there are more technical issues which require detailed diagnosis and invasive investigation, such as the use of lightweight blocks throughout the inner envelope wall on a block of flats.

Whatever the acoustic problem we can usually find an acoustic solution that will provide a sufficient acoustic design to satisfy Part E of Building Regulations. If you have suffered a sound testing failure then get in touch with us as soon as possible, as we should be able to offer you an expedient solution helping you to achieve practical completion in the quickest time possible.

If you would like more information in regards to sound testing or acoustic design, please follow our blog at:, or contact us on 01525 303905 or visit our website at:  

Designing Buildings to Pass Sound Testing

Designing Buildings to Pass Sound Testing

Designing Buildings to Pass Sound Testing
From the very start of the design phase of a new building, it’s extremely important that careful consideration is given to the acoustic element the building.

By getting us involved at the start of the design process we can undertake a comprehensive acoustic design reviews and on-going site surveys. We always advocate meeting with the design team at the earliest opportunity to go through all acoustic elements for the building’s design, taking into account the site constraints and the most cost effective method of achieving Part E of Building Regulations. We try to forward of any possible ‘onsite’ construction problems and difficulties in achieving successful acoustic construction and subsequently the sound testing for Part E.

Acoustic Design Services

Acoustic Design Services
Once we have completed the acoustic design review our services don’t finish there. We provide the site team with on-going design support and site visits. You will have direct contact with the allocated acoustician from the start of the process through to the successful completion of the project.

Once the first phase of the building is completed, we can undertake sample sound testing to ensure the acoustic design and onsite construction methods are sufficient to pass Part E sound testing.

When it comes to refurbishment projects i.e. house converted into flats and/or an office block into flats we can undertake a sample test of the existing wall and floor construction. Once we have established the sound levels for the existing construction we can then look at extent of the acoustic upgrades to attain Part E Complaisance. This is much more effective than just forwarding an acoustic design that may be to excessive and expensive when the existing construction is already ‘acoustically’ robust and therefore only needs to improve by a few dB.

One problem we often encounter (without our design input) is that the building marginally fails during the sound test. The potential problem that is often overlooked is that many types of acoustic design/materials have attained an acoustic rating within a laboratory. It is very difficult and extremely unlikely that the sound levels achieved on a construction site will be as good as in the confines of a stringent laboratory environment.

When the construction assembly is tested in the lab, it is also certified and an exact description of the materials and the installation techniques are described in detail and followed to the letter, obviously this should be replicated on the your site as closely as possible, however this seldom happens. This is one of the reasons why a 5dB point difference is allowed between the construction design on paper and the actual on site construction performance. When you consider that sound doubles every 10dB, then 5dB can make a huge difference to the overall performance of the dividing partition under test. If consideration is not allowed for during the design process then there will be a greater chance of a sound test failure on your project. 

Another potential problematic area of sound transference and potential sound test failures is down to flanking sound. Noise flanking is when travels along a continuous path due to insufficient isolation/break within the building wall & floor elements. One of the most common flanking paths is along the inner leaf of an external cavity wall. This may be due to lightweight block construction resulting insufficient mass to prevent noise transference.  

Unwanted noise travelling along flanking paths makes the building structure vibrate and this causes the sound to radiate into your room. One 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). APT can help to locate the flanking sound and propose a cost effective design that will pass the sound testing and satisfy Part E of Building Regulations.

For the smaller projects, we undertake a more simplified acoustic design service consisting of a review of the design drawings, such as to floor plans and sections. This usually takes place straight after planning has been approved as increased cost savings can be realised at the earliest stage. We can also undertake sample sound testing if the client is not sure of the existing onsite construction.

We can then evaluate the building design to ensure that it the walls and floors are capable of meeting the acoustic requirements of Approved document E.

Some of the main areas we consider are:

•             There are no potential flanking points, where isolated partitions are wrongly mechanically fixed together to caused noise bridging or the wrong materials have been specified such as lightweight blocks etc.

•             The acoustic treatments for Soil Pipes, Stair Cases Steel Beams etc. to ensure they are acoustically fit for purpose, as these are some of the many areas that get missed.

•             Acoustic floor treatments are compatible with the proposed floor finishes i.e. Carpets, Laminates, Floor Tiles and under floor heating systems.

•             The Lighting specification to, ensure they are acoustically complaint to the overall design i.e. down lighter design etc.

If you would like more information in regards to sound testing please follow our blog at:, or contact us on 01525 303 905 or visit the APT Sound Testing website.