Air Tightness Testing, Certified by AF-Acoustics, in UK

Air tightness testing determines the quantity of air coming out of cracks in a building. It is also known as air permeability testing or air leakage testing. In 2006, Approved Document L was reviewed and building regulations for air permeability became more stringent. The test is presently a requirement for new buildings and reconstructions.

Revisions were made to building regulations to address air leakages – a process where air escapes through any opening in the building, affecting its energy efficiency. AF Acoustics certificates are certified by Air Tightness Testing and Measurement Association (ATTMA). ATTMA is an association of specialists that concentrate on promoting the best air tightness measurements and air permeability testing techniques. Located in UK, our company is a committed and accredited air permeability testing service provider; we provide air testing services. You can also call or email us for any of these services:

  • Assessments
  • Consultancy
  • Part F mechanical extract fan flow rate testing.

Our air leakage test certificate is approved by ATTMA and is an indication that a building has been signed off by building control. If you want specialist air pressure testing services in UK, AF Acoustics’ tightness testing services will

  • Describe the process to you,
  • Highlight possible problem areas that might occur during testing,
  • Conduct the air tightness test, and
  • Give advice on improvements based on the outcome of the test.

AF Acoustics provides services that are cost effective and of high standard.

Our Guarantee

  • Over 15 years experience
  • State of the art equiptment
  • Onsite Support
  • Next Day Report Turn Around
Call us today for an assessment on 020 3372 4430
Or you can email us at info@af-acoustics.com

Air Tightness Testing Explained

Air tightness testing involves calculating the quantity of air which escapes through holes in the building fabric. Air tightness testing is also known as air pressure testing or air leakage testing. Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric (often referred to as infiltration or draughts) and not ventilation, which is the controlled flow of air in and out of the building. Draughts are uncontrolled ventilation. Using air tightness testing, the total air lost can be estimated. When too much air leaks through a building’s fabric, heat loss occurs, making the occupants uncomfortable. The government aims to lessen the quantity of air flowing from newly built buildings. Therefore, regulations have been put in place to reduce uncontrolled ventilation from the building envelope, sustaining the right temperature conditions without using so much fuel. With air tightness testing, you can determine whether or not air is leaking from a building’s envelope, the build quality and energy efficiency of new developments. Most building designs take air pressure into account at the beginning of construction in order to have an air-tight envelope and measure up to the required standards. This can make a building more energy efficient since air leakage is under control. It will also be cost effective and of high quality.

What Air Leakage Is

Air leakage is uncontrolled air movement in a building due to cracks. Air leakage is the uncontrolled movement of air into and out of a building through gaps and spaces in the building’s fabric. Also called infiltration, it differs from ventilation which is the regular, planned and restrained flow of air into a building. It leads to heat deprivation when cold draughts happen and warmth is needed the most. Because air leakage is uncontrolled ventilation, excessive air flows into the house during windy and wintry weather. How do you know if a building is energy efficient? By testing its air permeability. This lets the occupants know if the building meets standard air-tightness requirements. Air tightness testing is compulsory for all new constructions and non dwellings with a floor area over 500m² in England and Wales. This came into effect in 2006.

What Are the Problems Air Leakage Can Cause?

Air leakage causes heat loss. During windy weather, cold air infiltrates a building through the openings in its fabric. This results in heat loss. The infiltration of chilly air causes exfiltration, making warm air within the building escape through the spaces in other parts of the building. The water vapour in the moist air condenses on the inner wall surface holes. After a while, it is absorbed into building materials and diffuses, causing potential structural problems. Wet wooden framing or sheathing can rot and break down, diminishing its strength.

As the years go by, these conditions can result in structural damage.
Other damages that can occur are cold homes which make occupants uncomforta-ble, increase in heating bills to make the internal temperature warmer, and more carbon dioxide discharge since additional heat is required.

The key to minimising the damage potential of moisture is effectively managing the flow of air into and out of the building. Air leakage and vapour diffusion are minimised when barriers are installed. Proper ventilation, whether active or passive, is critical in expelling undesirable damp scents, water vapour and polluting substances.


Why Must We Do an Air Tightness Test?

The energy performance of a building is determined by how air tight it is. Energy performance affects CO2 released from buildings. As a result, air tightness testing is a method government has devised to regulate climate change. Heating buildings involves burning fossil fuel which increases CO2 emissions and causes global warming. Reducing air leakage reduces heat loss, which in turn reduces the amount of energy a heating system uses. Individuals living in buildings with high levels of air leakage may have medical problems. Houses. Low ventilation and uncontrolled air leaks result in mould growth and moisture which can cause potential health issues. The best advice is to “Construct tightly, ventilate properly”. Excess air leakage leads to moisture in the building envelope, causing large repair expenses and medical issues because of mould.

When Is an Air Tightness Test Needed?

A building should ideally be air tightness tested early in the construction process and again at the end of the building project, although sometimes only the final check is carried out. The test results are part of SBEM and SAP calculations, therefore they influence the total energy ratings of new buildings. Larger residential developments do not require testing to be completed on each individual property, instead, testing is undertaken on the different dwelling types within the development. Selective testing has a penalty of +2m3/h/m2. If target score is 5m3/h/m2, air tightness test score will have to be 3m3/h/m2.

If your building has not been pressure tested, its assessed air permeability would be the average score of buildings like yours in the area +2m3/h/m2 at 50 Pa. Selective testing is not advisable, as it does not give a realistic picture of the air tightness of each individual building. A tested property might be a lot tighter than an untested property. Also, the penalty implemented on the untested houses make air permeability rates very difficult to achieve.

Why AF Acoustics Is the Right Choice for Your Air Tightness Testing

AF Acoustics air tightness testing professionalism has helped many homes and business owners in UK. Our clients highly recommend us for the following reasons.

Great service and expertise

Our vast experience in serving a variety of clients in UK guarantees we have the expertise to satisfy your needs regardless your unique circumstances, type or size of property. We’ll work with you to carry out our tests and consultations at times that are convenient to you, delivering an exceptional quality, convenient service. Do you need trustworthy professionals who will provide great results in UK? Contact AF Acoustics today.

Registered member of the Air Tightness Testing & Measurement Association (ATTMA)

We are registered with the Air Tightness Testing and Measurement Association (ATTMA), an organisation that is centred on technical excellence in all air leakage measurement methods. ATTMA, the leading air leakage testing body in the UK, has recognised the quality of our services.

When Can You Call Us to Test Your Building?

Our comprehensive air permeability testing in UK is available. We have responsive scheduling options. Schedule for your air leakage testing at your comfort. You won’t get delays or difficulties when scheduling.

Test Certificates Get to You on the Next Day, Where Feasible

In order to satisfy our clients, AF Acoustics strives to provide test results and certificates on the next day.

Competitive Pricing

Save money by paying lower rates at AF Acoustics. As a business with low overheads, we’re able to give you one of the best air leakages testing services in UK at reduced costs.

Call us today for an assessment on 020 3372 4430
Or you can email us at info@af-acoustics.com

Get Air Leakages Test for Homes and Commercial buildings in UK

Regardless of the size, type, or complexity of your domestic or commercial building in UK, we can provide you with air tightness testing, carried out by an experienced and professional air tightness tester and issue you a certified ATTMA certificate. The best way to determine how much air seeps through a building’s fabric is through air permeability testing. The result of the air leakage test is expressed as a quantity in the form of The test results are described as m3/h/m2 – (m3 per hour) per square metre. of a building envelope.

Air leakage testing is required by Approved Document L1A and L2A. The design-stage SAP assessment or SBEM of a construction records its required air permeability rate. While the law requires the highest air permeability rate to be 10m3/h/m2, your building might have to get a lower rate to meet the carbon emissions target. Excess air leakage causes heat loss, greater carbon dioxide discharge and can make occupants uncomfortable due to the influx of cold air. It also causes wind washing and thermal bypassing, resulting in lower energy performance. Warm air within a heated building rises and lowers the pressure at the building’s base to draw in air through the openings in the building fabric, leading to exfiltration or infiltration. To get signed off by building control in UK, all buildings are to undergo air tightness testing and measure up to the required energy efficiency standards. Clients and employees will be at ease in their surroundings. In addition, you get lower heating and cooling costs. A comfortable environment results in a higher productivity rate.

Part L Test

Since Approved Document L was reviewed in 2006, building regulations have demanded that new and rehabilitated constructions conduct air tightness test. Other names for air tightness are air permeability rate or leakage rate. Although not always seen, air leakage can occur through any gap, space or crack in a building’s fabric. Samples of houses in an area and all non-domestic buildings with more than an area of to m2 must be tested, according to Part L of the Building Regulations. The highest air permeability target set is 10m3/h/m2 but your building might need a much lower one. Air leakage is vital to a building’s energy efficiency and is needed to meet Building Regulations Part L and carbon emission standards.

Part F Test Explained

We can complete all your Part F and Part L testing requirements. With our organisation, you receive:

  • Expert fan flow rate testing
  • Experienced air pressure testing
  • Professionals who provide Energy Performance Certificate, water and SAP calculations.

According to Part F, it is compulsory for a flow rate test to be conducted on all mechanical extract fans of new buildings. Building Control Body (BCB) will see proof that the test has been conducted before signing off your building. There are three alternative methods which can be followed to test, record and report the testing of extractor fans. Use method 3 – the minimum benchmark method, which tests extractor fans with vane anemometers. This is our testing procedure.


The types of Air Tightness Testing Services We Offer

Here are the descriptions of the ways air permeability can be tested: A single blower door fan is the instrument used for the first level to examine single buildings and smaller non-dwellings from 1m3 to 4000m3. Level Two: Single and multifaceted buildings 4000m3 gross envelope volume and above are tested for air pressure. High rise (LCHR) buildings and phased handover/zonal buildings are excluded from this level. Air tightness testing for phased, zonal handover and LCHR constructions is done.

We Offer Air Leakage Testing of Apartments and Houses to Meet Approved Document L1 Standard

The measurement of air emitted by a building is tested to determine air permeability rating. The result is written as m3/h/m2 – (m3 per hour) per square metre of building envelope. Air leakage testing is a requirement of Approved Document L1A. In order to comply with the carbon emission target, it is necessary to achieve a lower air permeability rate. The required air permeability rate for a dwelling can be found on the design-stage SAP report for that dwelling. Air leakage leads to heat loss, increased energy bills, greater CO2 emissions, and an uncomfortable atmosphere for inhabitants due to draughts.

Commercial Building Testing as Required by Approved Document L2A

Air leakage testing is the measurement of uncontrolled ventilation from a building’s fabric. The test results are inscribed using m3 per hour per square metre. Document L2A of Building Regulations declares air leakage testing to be mandatory. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. A building will usually have to achieve a lower rate to meet the SAP or SBEM assessment. To get your building’s required air permeability rate, check its design-stage SAP or SBEM assessment. An excessive amount of air leakage leads to greater energy expenses, heat reduction, carbon dioxide discharge and draughts.

Air Leakage Test of Smoke Shafts for Auto Vents

We provide smoke shaft tests to make sure it is air tight enough to let the automatic opening ventilation work optimally when it’s installed and commissioned. The automatic-opening vents are a key part of the fire strategy for multi-storey buildings to extract smoke in the case of a fire. For the vents and fans to operate at the expected level, the smoke shaft must be air tight to create a difference in air pressure and give emergency services when needed. AF Acoustics aims for the air permeability requirements of the automatic opening vent producers, so that their product can perform optimally. An air pressure test is conducted using a fan installed in the shaft. The openings for ventilation grilles and extract points on each floor are closed so that the state of the shaft itself is known. The fixing and commissioning of the auto opening vents happen after the test is completed.

Air Flow Measurement of Domestic Ventilation (extraction fan testing)

The requirement for air tight buildings that are properly insulated has brought about the need for ventilation systems that are adequately installed and function at an optimal level. We have the capacity to test extraction rates. A building must have an optimal ventilation system to dispel humidity from bathrooms, kitchens and other rooms and extract odours and pollutants. We can also help you meet the Building Regulations targets. Another of such targets, as stated by Part F, is to have the standard intermittent extractor fans, like kitchen and bathroom extractors, in new constructions measured for air flow and results given to Building Control before the construction work is completed.

Particular Test and Building Readiness Operation

When a building is checked for the quantity of air flowing through the gaps in the fabric, it has undergone an air tightness test. When air leakage is reduced in a building, the occupants will not experience discomfort and the energy performance will increase.

External claddings and the internal building finishes might obscure a gap in the building fabric. This makes it hard to notice and can results to potential air leakage. The only satisfactory way to show that a building fabric is airtight is to detect and measure leakage paths within the building fabric.

Under the new policies of building developments, the lowest number of domestic buildings developers have to test in an area is 20%. However, this depends on the quantity of different house kinds to ensure there is a regular sample throughout the survey. We recommend that all dwellings be tested, as there is a penalty for developments that are not tested.

What Should You Do Before Testing Your Building?

Our test engineers would like to see the drawings (plans and elevations) and design air permeability requirements of your building before taking the test. This is to have the needed information for the building and to know the size of the building envelope before coming to the site. Air tightness testing lasts for 30 to 60 minutes and wind speed is not more than 6m/s. To prepare the site for the test, do the following:

  • Turning off all range stoves and cookers (if applicable)
  • Turning off mechanical vents
  • Shutting all windows and external doors
  • Sealing ventilation grids and smoke vents
  • Filling the drainage stops

How We Measure the Building Envelope

Before coming to the site, we get the measurement of the building’s envelope. The building envelope, is the physical barrier between the exterior and interior of a construction. We use the building envelope measurements to get the right results when testing for air tightness.

Air Permeability & The Envelope Area

Air permeability is calculated at air leakage rate per square metre of envelope area. In relation to air permeability, the air envelope area is the total area of the measured part of the building without subtracting from the area of the junction of internal walls, or floors and ceilings. The envelope area of a terraced house includes the party walls while that of a flat in a multi-storey building includes shared ceilings, walls and floors.

Air Change Rate

Air exchange rate is vital to ventilation design but it isn’t used as the determinant of the actual design or calculation. To calculate ventilation rates for domestic buildings, the area and number of people living in the building are considered.

Cold Roof Envelope Area Measurement

When evaluating the roof area of a building, it is important to ensure the area is the same as that of the ground floor. A cold roof is a roof that has its insulation in the ceiling and there’s a huge space between the insulation and rafters.

Measuring a Warm Roof Construction’s Envelope Area

A warm roof has the insulation running along the pitched roof rafters with an air barrier normally running parallel along the inside face of the insulation. In the warm part of the insulation, is the barrier between the conditioned and unconditioned space.

Building Preparation

  • Open and secure all internal doors;
  • Close all windows;
  • Switch off all mechanical ventilation systems;
  • Seal vents;
  • Close smoke vents;
  • Fill all drainage traps; check weather conditions (wind speed, temperature, barometric pressure);

How the Test Is Done

Examine the wind speed, barometric pressure and temperature. Connect a fan to an aperture within the construction envelope. For example, the door. Set up testing equipment. Using the fan, measure the air flow volume, from the building fabric. Slowly raise the fan speed from 20-25Pa to 55-60Pa. Record pressure differences across the building at each fan speed.

Measuring air leakage

Our air leakage measurement involves picking out the gaps where air leakage takes place, recording the test information, sending results to customers in a technical report and advise clients on repair methods in the case of a test failure. Air Pressure Testing & Compliance

The positive effects of an air tight building with efficient ventilation (natural, mechanical or a combination) cannot be underestimated. Here they are: Reduced heating expenses because of lower heat loss, with less need for equipment that has high heating ability. The ventilation system will operate optimally Lower levels of mould due to less moisture collecting in gaps and cavities. Fewer draughts and enhanced comfort Our air leakage tests are conducted according to building regulations and targets, whether we’re testing a small dwelling or big commercial development. Not only do we provide services that meet building regulation targets, when you employ our services, you’ll save money and spend less in the long run. We test for air permeability, provide consultancy services and support services and review the designs of all buildings, whether domestic or commercial, large or small.


Best Practice Processes

Any new building has to be air tight. The 2010 Approved Document L1A of Building Regulations has made it compulsory. This regulation was put in place to conserve fuel and power. The dwelling should be tested for air permeability in line with existing building standards, as stipulated by Approved Document Part L1A.

Determining Air Leakage in buildings (Dwellings), According to Technical Standard L1

The Air Tightness Testing & Measurement Association (ATTMA) provides the technical standard to be followed for the testing of dwellings in the UK as set out in Building Regulations and other documents. This Technical Standard provides detailed guidance and clarification of BS EN 13829:2001: “Thermal Performance of Buildings. Determination of air permeability of buildings. Fan pressurisation method” and ISO 9972:2015: “Thermal performance of buildings – Determination of permeability of buildings – Fan pressurization method”, in order to ensure consistency by testing companies.

Call us today for an assessment on 020 3372 4430
Or you can email us at info@af-acoustics.com

Building Regulation Part L 2010 (England and Wales)

Undergoing an air tightness test is compulsory for your new building, according to Part L of Building Regulations. For developments of two or more dwellings, an air leakage test should be carried out on the three units of each dwelling type; or 50% of all instances of that dwelling type. If the development has one or two dwellings only, an air tightness test might not be taken if the DET/TER calculations assume a value of 15m3/h/m2. An SAP assessor can decide which buildings can use the assumed value successfully. A testing procedure required by Building Regulations is expressed in ATTMA TSL1 for dwellings and ATTMA TSL2 for non-dwellings. Both residential areas and many non-Dwellings are to take the air leakage test. Non-dwellings with a typical floor area less than 500m2 may be exempt. Where testing is not carried out, an assessed air permeability of 15 m3/h/m2 must be used in calculations.

Building Regulation Requirements Part L (England and Wales)

In January 2015, the ATTMA Scheme for Competent Air Tightness Testing Firms and Their Testers (The ATTMA Scheme) was launched. It is an industry competence scheme authorised by the government and specified in Technical Standard L1 & L2. Minimum Technical Competence (MTC) and National Occupation Standard (NOS) documents are the basis for the scheme.

Air tightness testers can be divided into three categories

  • First Level – For buildings not more than 1m3-4000m3, typically single and smaller non-dwellings, a single fan is used to carry out air tightness testing.
  • Level 2: Testers can test all buildings except large, complex and or high-rise buildings and or phased handover or zonal buildings unless part of a team managed by a level 3 tester.
  • The third level expert tests big and complex zonal and phased buildings and complex high-rise buildings.

Air Leakage Test Report

Air leakage test reports are given by authorised organisations that test different buildings. First, extraction fans are closed. Then, the details and results of the tests are written down in a report. The report will be produced in accordance with company’s procedures, the relevant standards and the requirements of all relevant governing bodies.

Test Results

We analyse our tests and results for any divergence from the standards required and check the air pressure rate against target rate. That way, our results are expressed in line with test standards. The identity of the customer, tester, building and address are correctly written in our report. If a building fails the test, we provide remedial suggestions before a retest is carried out.

Resources Air Tightness Checklist – Dwelling

Send us your building design air permeability target and crosscheck the list below before we get to the site.

Air Leakage Pathway List –Ensure you thoroughly check the following equipment. Fill up drainage traps. Here are the pieces of equipment to cover, fill or seal:

  • Extract fans
  • Hoods of cookers
  • Drainage traps
  • Metre boxes
  • Boilers
  • Radiators, fans and heaters
  • Hot water tank
  • Chimney
  • Air bricks
  • Skirting and coving
  • Bath panel
  • Tumble drier extracts
  • MVHR
  • Soil panel

Here are the appliances you should seal temporarily;

  • Cooker hoods
  • Extractor fans/MVHR terminals
  • Trickle vents
  • Chimney flues and air bricks

Air Tightness Testing FAQ’s

Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric of a building (sometimes called infiltration or draughts).

This is not to be confused with ventilation. Which is the controlled flow of air into and out of the building through purpose-built ventilators that are required for the comfort and safety of occupants.

Too much air leakage leads to unnecessary heat loss and discomfort to the occupants from cold draughts.

At AF Acoustics, we will endeavour to help you identify air leakage/infiltration paths.

There are a number of methods we employ to do this, including:

  • Smoke pens– smoke can be used to identify where air is moving when the building is being tested
  • Depressurise the building –By depressurising the building air is drawn in and can be felt at the air leakage points, our experience will be able to pin point these locations easily, whist the building is being depressurised, we will be able to show you around and will point you to the areas that have air leakage. You will usually be able to feel the air blowing on your skin when you are close to leakage areas, using the smoke pens these leakage points can be seen as the smoke changes from a steady flow to a turbulent flow.
  • Smoke testing – if the air paths are less direct it may be necessary to use smoke puffers and/or fill the building with smoke and pressurise/depressurise again. Points of air ingress and egress should be identifiable.
  • Thermography – if it is still not apparent where air is escaping, infra-red cameras can be used to identify hot spots and cold spots on the internal and external surfaces of the building. This requires a temperature difference between the inside and outside.

In the vast majority of cases the first two methods are sufficient to identify the most significant air leakage paths along with our expertise we will be able to point our the problem areas should they arise. The air leakage areas will have to permanently sealed and the test repeated to reduce the air permeability of the building. Where problems are larger and sealing cannot be addressed on the day, the building may need to be re-tested at a later date.

A test certificate from The Air Tightness Testing and Measurement Association (ATTMA)

A testing procedure is to be carried out to comply with TSL1 for domestic or TSL2 for commercial. The test certificate will include sufficient information to describe the building tested e.g. location, type and size (the envelope area is an important component in calculating the air permeability and must be accurate) plus the design air permeability as well as the actual result. A testing procedure should be representative of the actual building performance.

An indicative result is available at the time of testing. Certificates can be issued within a day of testing.

If required, you can request all calculations including pre, and post environmental measurements, individual static pressures, envelope area breakdown, flow readings and calibration certificates at no extra charge.

Air permeability is essentially a function of the pressure difference between the inside and outside of the building and the air flow rate through the fan(s), necessary to produce a pressure difference. This is averaged out over the envelope area. The result takes account of environmental conditions.

The final air permeability at 50 Pa is based on a logarithmic graph of pressure difference and flow rate, the graph should:

  • Have at least 7 points (ideally 10 or more).
  • At least one building pressure >50Pa and at least on <50Pa, No building pressures >100Pa.
  • The lowest figure should be at least 10 Pa or 5 times the ‘static pressure’ (the pressure difference between inside and outside without the fans)
  • The readings should be no more than 10 Pa apart.
  • The correlation coefficient r2 >0.98
  • The gradient of the graph (n) should be between 0.5 and 1.0.

These are aspects that the building control should check carefully if choosing to accept air permeability results from non-accredited testing bodies.

Most air tightness tests for domestic units and simple commercial units are carried out in 45 – 60 minutes. This time may be extended if the test fails and leakage paths are investigated. We will normally charge for a retest depending on how much work is to be carried out.

On larger commercial units, which require 1 large air test fan, air tests take 1 hour if all temporary sealing has been completed prior to starting the air test.

If complicated or very large buildings are being air tested with multiple fan units, allow up to 4 hours for the test and longer if investigations are required.

The envelope area is calculated from the drawings and verified on site. The envelope of the building is all the surfaces that separate the heated interior from the unheated exterior of the dwelling. This includes walls, floors and the roof.

Generally, this involves mounting a door profile and incorporating one or more electrical fans into an external door opening(s). Depending on their orientation, the fans can be used to pressurise or depressurise the building. The resulting difference between the external and internal pressure can be used to calculate the permeability of the building envelope (given that the envelope area is known).

This permeability is an indicator of how air tight the building is, and whether there are openings in the envelope. Generally, 10 differential pressure points are taken at different fan flows to establish an accurate result for the building. Our certified specialised software is used to establish an accurate Air Tightness Test result.

Our experts at AF Acoustics will provide a simple checklist for building preparation, which includes the following:

  • The building should be ‘completed’
  • All external doors and windows closed
  • All internal doors wedged open
  • All fire dampers, ventilation louvres and trickle vents closed but not sealed
  • Mechanical ventilation turned off with inlet/outlet grilles sealed
  • All combustion appliances switched off
  • Drainage traps must contain water
  • Any ‘Aga’ type stoves must be switched off for a minimum of 24 hours prior to testing

All building preparations should be made before our test engineers arrive on the site this will ensure a smooth testing process and increase your dwelling’s chances of passing the test the first time. We will seal all the vents ourselves.

For multiple dwellings it may also be necessary to agree on the test programme with the building inspector before arriving on site.

Where possible, it is helpful to accurately calculate the envelope area and confirm the fan installation arrangements based on architectural drawings before coming to the site.

  1. How many plots are going to be tested
  2. The location
  3. The plans and elevation drawings, cross sections if possible
  4. The air permeability target
  5. A brief description of the property; e.g. does it have fireplace or a loft?

For dwellings, sufficient information is required to identify the different dwelling types and the number of each such as General Arrangement/Site Plan and Schedule (including other important details such as variation in storey height or construction method).

For buildings other than dwellings, the approximate envelope area is the key factor for quoting. It is required to establish the necessary fan arrangement. This affects the time on site and potentially the number of people, and this can be calculated from drawings – floor plans and elevations.

The testing body may also need to identify the potential aperture(s) into which test equipment is to be installed. In some circumstances this may require additional time on site, extra people or customised templates.

Approved Document L states that Building Control can accept evidence from BINDT or ATTMA Registered testers. However, the BINDT scheme was closed down at the end of 2014, subsequent to the last revision of Approved Document L. Additionally, The Independent Air Tightness Testing Scheme (iATS) is an authorised Competent Persons Scheme created for companies (including sole traders and partnerships) that carry out Air Tightness Testing.

The common leakage sites are:

All pipe works within the kitchen and bathrooms

  • Holes in the walls
  • Radiator pipe work penetrations in floors and walls
  • Sanitary pipes penetrating walls and floors
  • Junction between floor and wall under kitchens and baths
  • Junction lower floor / vertical wall
  • Junction window sill / vertical wall
  • Junction window lintel / vertical wall
  • Junction window reveal / vertical wall (horizontal view)
  • Vertical wall (cross section)
  • Perforation vertical wall
  • Junction top floor / vertical wall
  • Penetration of top floor
  • Junction French window / vertical wall
  • Junction inclined roof / vertical wall
  • Penetration inclined roof
  • Junction inclined roof / roof ridge
  • Junction inclined roof / window
  • Junction rolling blind / vertical wall
  • Junction intermediate floor / vertical wall
  • Junction exterior door lintel / vertical wall
  • Junction exterior door sill / sill
  • Penetration lower floor / crawlspace or basement
  • Junction service shaft / access door
  • Junction internal wall / intermediate floor

Our team of experts can support you through the following

  • Tender Stage – Estimate pricing structures and general advice
  • Design Stage – Desktop or site-based design team meetings
  • During Construction – Ongoing audits of the building, Building Control liaison, sample testing of completed areas of ‘comfort testing’ prior to final testing
  • Upon completion – preparation advice, shortly prior to the air testing, final testing and leakage diagnosis

Additional AF Acoustics services – including noise survey, sound insulation testing services noise impact assessments

Employing the services of a reputable and accredited air tightness testing consultant, such as AF Acoustics, can help identify and remedy potential problem details in a building design prior to and during construction.

The Air Tightness Testing and Measurement Association (ATTMA) is approved by Department for Communities and Local Governments (DCLG) and is listed in the Building Regulations as an authorised Competent Persons Scheme for air tightness testing.

As an ATTMA registered company, AF Acoustics is independently certified by ATTMA with a scope covering air tightness testing to the ATTMA Technical Standards (TSL1 & TSL2) and BS EN: 13829 (2001), demonstrating knowledge and understanding, which enables us to test both commercial and domestic developments in accordance with relevant building regulations.

Part L sets the energy efficiency standards required by the Building Regulations. It controls:

  • The insulation values of building elements
  • The allowable area of windows, doors and other openings
  • Air permeability of the building
  • The heating efficiency of boilers
  • The insulation and controls for heating appliances and systems together with hot water storage and lighting efficiency

It also sets out the requirements for SAP (Standard Assessment Procedure) Calculations and Carbon Emission Targets for dwellings. In addition to insulation requirements and limitations of openings of the building fabric.
Part L also considers:

  • Solar heating and heat gains to buildings
  • Heating, mechanical ventilation and air conditioning systems
  • Lighting efficiency
  • Space heating controls
  • Air permeability
  • Solar emission
  • The certification, testing and commissioning of heating and ventilation systems
  • Requirements for energy metres

Building Regulations are administered separately in England, Scotland and Wales.

The objective is to measure the volume of conditioned air escaping through the building envelope via uncontrolled ventilation at an induced pressure difference of 50 Pa. A simplified process is shown below:

  • Check site preparation / Prepare site – including temporary sealing.
  • Calculate the envelope area.
  • Take environmental condition measurements – wind speed, temperatures, barometric pressures.
  • Install door frame canvas for the fan into a suitable aperture(s), usually the front door.
  • Install fan(s) into frame canvas
  • Connect monitoring equipment.
  • Check the static pressure.
  • Take multiple pressure difference readings and record fan flow rate(s) – allowing sufficient time for the pressure readings to stabilise.
  • Check the static pressure.
  • Process the readings through appropriate software – check that readings fulfil the requirements of the standard.
  • If the building fails, attempt to identify/quantify air leakage/infiltration paths.
  • Disconnect measurement equipment.
  • Remove the fan(s).
  • Remove the door frame canvas.

No. However due to the penalties occurred to the air permeability value of non-tested properties, every property is usually tested. We can test all dwellings, including domestic buildings, industrial units, warehouses, schools, hospitals, residential care homes, hotels, offices, and retail units.

All new buildings and dwellings should be tested, but there are some exceptions and they are explained below:

  • ‘Small’ commercial buildings (with a floor area less than 500m2) may avoid the need to test by accepting an assumed poor value for air permeability (15m³/(h.m²) at 50 Pa) but this may add costs to other aspects of the building specification so that the building meets the overall target for emissions.

No. Air tightness testing applies to:

  • All new dwellings (based on a sampling rate)
  • All new buildings other than dwellings
  • Extensions to existing buildings that create new dwellings

Air tightness is an important factor in assessing the overall carbon emission of a building via the appropriate calculation methodology:

When a building is air tight, the amount of fuel needed to heat it is reduced. This conserves fuel and reduces the carbon dioxide produced, thereby lowering carbon emission and energy bills.

If you are building a new domestic property or commercial property of a certain size, it will need to undergo air tightness testing. This assesses the building for ‘air permeability’, checking for air leakage through gaps, holes and other areas. The Government has SAP (Standard Assessment Procedures) in place for air tightness testing, setting standards buildings must comply with to be energy efficient.

All residential properties and non-dwellings properties over a certain size (with a floor area greater than 500 m2) must undergo air tightness testing. With larger developments, a sample number of the buildings must be tested, depending on the size and construction of the properties. However, in practice all dwellings are likely to be tested, as non-testing attracts a severe penalty.

In a property where air tightness is below the recommended standard, the following problems can occur:

  • heat loss
  • discomfort (cold homes)
  • increased heating bills (to counter the cold)
  • greater CO² emissions (as result of additional heating required)

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Gerard Finn

AF Acoustics lead air tightness testing Specialist, Gerard is your first port of call for all air tightness questions enquiries and surveys.

Working Hours

  • Monday 08:00 - 18:00
  • Tuesday 08:00 - 18:00
  • Wednesday 08:00 - 18:00
  • Thursday 08:00 - 18:00
  • Friday 08:00 - 18:00
  • Saturday Closed
  • Sunday Closed