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

The measurement of air escaping from a building is called air tightness testing. It is also referred to as air permeability testing or air pressure testing. Since Approved Document L was reviewed in 2006, air tightness testing has become an essential part of building regulations for newly completed and rehabilitated buildings.

Air leakage occurs through any opening in the building envelope and can affect a building’s energy performance, this has been addressed by changes to the building regulations. We register our air tightness certificates with the Air Tightness Testing and Measurement Association (ATTMA), an organisation that encourages proper air leakage applications and promotes quality air tightness screening. AF Acoustics, a licensed air tightness testing company, is available to provide testing services at your request. Our address is Wallington. You can also call or email us for any of these services:

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

We are registered members of the ATTMA. As a result, our air tightness certificates prove that the building requirements for your building have been met. If you want specialist air pressure testing services in Wallington, 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 a quote on 020 3372 4430
Or you can email us at info@af-acoustics.com

Air Tightness Testing Explained

Air tightness testing is a method of measuring the extent to which air is lost through leaks in the building fabric. It is sometimes referred to as air leakage testing or air pressure testing. Air leakage should not be confused with ventilation. Also called draughts or infiltration, air leakage is unrestrained movement of air through holes in a building fabric, while ventilation is the restrained and planned movement of air. Air leakage is uncontrolled ventilation. Air tightness testing is the approved method for gauging the entire air that has leaked through a building fabric. Unrestrained air movement leads to heat reduction, making the inhabitants of the building uncomfortable. Air leakage from buildings causes heat loss, more energy is then used to keep the building warm, this is a cause of excess CO2 emissions. This has resulted in regulations which are centred on decreasing air leaks from the building fabric, therefore lowering CO2 emissions. Calculating the emission of air from a building’s fabric, establishes the energy efficiency of the building. Building plans will often consider air tightness at the beginning stages of development so as to measure up to stricter building standards. Understanding this at an early stage can make a build cost-effective, of high quality, and energy efficient by minimising uncontrolled air leakage.

What Is Air Leakage?

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. It is not the same as ventilation which is regulated air flowing into a building. It is also called infiltration. Because of the nature of air leakage, excessive air infiltration might occur in a building when the weather is windy and chilly. This results in loss of warmth and an unpleasant cold draughts. 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. All commercial buildings over 500m² and new buildings in England and Wales are mandated to test for air tightness and permeability, according to the 2006 Building Regulations.

What Is the Impact of Air Leakage?

When air escapes uncontrollably from a building, heat reduction occurs. When the weather is cold and windy, unwanted air seeps into a building through the holes and cracks in its fabric, causing heat loss and discomfort. Once there’s infiltration, exfiltration will occur in another part of the building. Warm, moist air seeps into cool cavities in the building’s fabric. When moist air hits a cooler surface within a wall structure, water vapour in the air can condense and collect inside these spaces. Moisture can then be absorbed in building materials and cause serious defects. Wooden sheathing or overlay becomes wet, making it weak.

Over the years, these problems can damage the building’s structure.
Other impacts include:

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

The key to minimising the damage potential of moisture is effectively managing the flow of air into and out of the building. A properly installed air barrier minimises air leakage, which, in turn, minimises the potential for water vapour to condense on vulnerable wall structures. To get rid of pollutants, water vapour and moisture odour, the building must be well ventilated.


Why You Should Conduct an Air Tightness Test

Air tightness is a key factor in building energy efficiency, and is a part of government-led initiative to combat climate change through improvements in building energy performance. Environmental change caused by carbon dioxide emissions and global warming is partly aided by the burning of fossil fuels to generate heat. The reduction of air leakage leads to lower heat loss and quantity of heat generated in a building. Uncontrolled air leakage also results in health problems. Coupled with poor air circulation, it leads to the growth of mould and mildew. The best advice is to “Construct tightly, ventilate properly”. High levels of air leakage can lead to moisture ingress into the building fabric, resulting in expensive repair costs and potential health problems due to mould.

When Is an Air Tightness Test Needed?

It is best practice to conduct at least two air tightness testing procedures, one early in the build and another at the end. Newly completed constructions’ energy ratings can be influenced by the test results, as they are used in SAP and SBEM calculations. Large residential areas do not need each building to be tested. Instead, different types of dwellings are tested. With selective testing there is a penalty of +2m3/h/m2; if the target score is 5 m3/h/m2 and selective testing was applied, the air tightness test would have to achieve a lower score of 3.

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 Pick AF Acoustics for Your Air Tightness Testing?

AF Acoustics air tightness testing professionalism has helped many homes and business owners in Wallington. We come highly recommended by our clients because of the following guarantees.

Helpful service and information

Our experience in serving diverse customers in Wallington is proof of our ability to satisfy your requirements no matter the size and type of building, or your circumstance. Our qualified air tightness testing professionals will work around your schedule, so they fit into your project seamlessly, providing a quality service as conveniently as possible. If you need knowledgeable and trustworthy air leakage experts who can provide exemplary results, AF Acoustics is the team you need in Wallington.

We Are Registered Members of the Air Tightness Testing and Measurement Association (ATTMA)

We are registered members of the Air Tightness and Measurement Association (ATTMA). ATTMA encourages proper air leakage applications and promotes quality air tightness screening, and has recognised our impeccable professional services.

When Can You Call Us to Test Your Building?

We want you to be able to access comprehensive air tightness testing in Wallington whenever you need it. Pick a time that is convenient for you in our responsive scheduling options. We won’t make you wait or make the process complicated.

Quick Turnaround on Test Certificates Where Possible

AF Acoustics offers a professional and reliable service; we understand that our clients are keen to get their test results as quickly as possible, to facilitate this process we strive to deliver next-day turnaround on test certificates.

Competitive Pricing

AF Acoustics, a small business with low overheads, offers one of the best prices in Wallington and guarantees professional services.

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

We Conduct Tests for All Types of Buildings in Wallington

Regardless of the size, type, or complexity of your domestic or commercial building in Wallington, 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. Air permeability testing calculates how much air moves through spaces in your building’s fabric. The test results are described as The test results are described as m3/h/m2 – (m3 per hour) per square metre..

Approved Document L1A and L2A requires that buildings know their air permeability rates by taking the air leakage test. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. In order to comply with the carbon emission target, it may be necessary to achieve a lower air permeability rate. The required air permeability rate for each building can be found on the design-stage SAP assessment or SBEM for that building. 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. Exfiltration/infiltration of air is caused by the difference in air pressure inside and outside the building. Lower pressure occurs as warm air rises and brings air inside through any available opening. To get signed off by building control in Wallington, all buildings are to undergo air tightness testing and measure up to the required energy efficiency standards. Buildings where businesses are conducted will not cause discomfort to employees and clients because they have the legal air permeability rating. It will also help you reduce the cost of maintaining heating or cooling in your commercial building, making it more productive.

Part L Test

Air tightness testing has been a compulsory part of the Building Regulations for new dwellings, renovations and commercial projects since the revision of Document L in 2006. Air tightness is also called air leakage rate or ‘air permeability’ rate. Any hole or crack in a building fabric is a spot where air leak can take place. Air leakage points are not often visible. Part L of the Building Regulations requires that all commercial buildings greater than 500m2 undergo air tightness testing and a selection of residential buildings in a development be tested. To comply with Part L the measured air permeability minimum requirement is 10m3/h/m2 but usually your air permeability target will be much lower. Air permeability is key in the following areas: i. A construction’s energy performance, ii. CO2 emission targets iii. Building Regulations Part L standards

The Part F Test

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. You can test, document and report the test of your building’s extractor fans in three ways. Use method 3 – the minimum benchmark method, which tests extractor fans with vane anemometers. This is our testing procedure.


Different Ways We Test for Air Permeability

Air Tightness Testing has different tiers, depending on how complex a building is and its size. Find them below: A single blower door fan is used for air tightness testing for single buildings and smaller non-dwellings not more than 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. The third level tests big and complex zonal and phased buildings and complex high rise buildings.

Testing of Air Permeability of Residences and Apartments, in Accordance with Document L1 Stipulations

An air leakage test is a test to determine the level of uncontrolled air flow through gaps or cracks in the fabric of a building. The result is written as m3/h/m2 – (m3 per hour) per square metre of building envelope. Air pressure testing is compulsory, according to Approved Document L1A. Your building may need a lower rate to meet the CO2 discharge target. You can find the required air permeability rate of your building in its design-stage SAP assessment SBEM. Air leakage leads to heat loss, increased energy bills, greater CO2 emissions, and an uncomfortable atmosphere for inhabitants due to draughts.

We Offer Air Leakage Testing of Business Buildings to Meet Approved Document L2A Standard

The measurement of air emitted by a building is tested to ascertain air permeability rating. The result of the air leakage test is expressed as a quantity of air leakage (m3 per hour) per square metre of building envelope. Document L2A of Building Regulations declares air leakage testing to be mandatory. The highest air permeability rate for your dwelling when tested should be 10m3/h/m2. Your building may need a lower air permeability rate to meet the SAP or SBEM assessment. You can find the required air permeability rate of your building in its design-stage SAP or SBEM assessment. Air leakage causes heat loss, increased energy bills, greater CO2 emissions, and an uncomfortable atmosphere for inhabitants due to draughts.

We Offer Smoke Shaft Air Pressure Testing

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. Smoke needs to be cleared out in the event of a fire. The automatic opening ventilation is a vital aspect of the fire strategy for high rise buildings. For it to expel smoke from a building and keep the occupants safe during emergencies, the shaft must be air tight enough to create substantial pressure difference. We work towards air permeability targets set by the automatic-opening ventilation manufacturers that allow their equipment to operate effectively. The shaft undergoes air leakage testing when fans are placed inside it. Once the fan is fixed, the extract points and ventilation grilles on each storey are sealed to ensure that the shaft is in proper condition. The fixing and commissioning of the auto opening vents happen after the test is completed.

We Offer Extraction Fan Testing

The requirement to build more highly insulated and air tight buildings means that it is increasingly more important to ensure buildings are not only adequately ventilated but the ventilation system is suitable and commissioned correctly to ensure its effective operation. We evaluate extraction rates. This is done to meet the Building Regulations standard. Make sure the ventilation system is efficient, expels pollutants and odours, and reduces humidity, especially in kitchens and bathrooms. Part F states that all new constructions must have intermittent extractor fans whose air flow rates will be calculated and the results given to Building Control before the building work is finished.

Explicit Test and Building Preparation Process

An air tightness test measures the extent of air leakage in a building. When air leakage is reduced in a building, the occupants will not experience discomfort and the energy performance will increase.

Holes and spaces in a building’s fabric might be hidden by the internal building finishes, making them hard to find. The only satisfactory way to show that a building fabric is airtight is to detect and measure leakage paths within the building fabric.

At least 20% of different kinds of dwellings in a development have to be tested, according to new regulations; but the reliability of the sample from this type of testing is determined by the types of buildings in the development. We recommend that all dwellings be tested, as there is a penalty for developments that are not tested.

Pre-Test Requirements

Send the drawings of your dwelling (plans and elevations) and its target air permeability requirements to our test engineers. The test engineers would like to have the information needed for the test before coming to your development. Our air leakage test is done between 30 and 60 minutes, and the wind speed is a maximum of 6m/s. In preparing the site to create an air-tight environment:

  • Seal and turn off all ventilation, smoke vents and mechanical ventilation systems
  • Close the windows and open internal doors
  • Fill drainage traps
  • Switch off range stoves/cookers 24 hours before the test

Calculating the Building Envelope

We undertake building envelope measurements before getting to the dwelling for the test. The building envelope is the surface area of the thermal boundary of the building. The building envelope calculations are taken from the drawings and used for our air tightness testing.

Air Permeability from the Envelope Area

Air permeability, according to Approved Document L1A (2010), has to do with “air leakage rate per hour per square metre of envelope area at the test reference pressure differential of 50 pascals (50n/m2)”. The building’s envelope area has to do with the total area of all the floors, walls, and ceilings bordering the internal environment, including those below external ground level. These include shared walls, floors and ceilings in storey buildings. Internal dimensions are used to measure the envelope area.

Air Change Rate

Air changes per hour are crucial to ventilation design, but it is only occasionally used as the base for the design or calculation. To calculate ventilation rates for domestic buildings, the area and number of people living in the building are considered.

Cold Roof Construction Envelope Area Calculation

It is important to make sure the roof area and ground floor area of a building are equal. A cold roof is a roof that has the thermal insulation put in the ceiling with wide space between the insulation and pitched roof rafters.

Calculating the Envelope Area of a Warm Roof

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. The envelope area is the boundary or barrier containing the overall internal ‘conditioned space’ separating it from the external environment (or non-conditioned spaces and adjacent buildings), and this is located on the warm side of the insulation.

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);

Process for Testing the building

Examine the wind speed, barometric pressure and temperature. Fix a fan to an aperture, usually the door, in the building. Set up testing equipment. Using the fan, measure the air flow volume, from the building fabric. Raise the fan speed from 20-25Pa to the highest speed of 55-60Pa. The pressure differences in the building at each fan speed should be calculated.

Evaluating Air Leakage

We analyse the air tightness test data, point out any air leakage path and send a report to clients. If the building fails the test, we suggest remedial measures to the client. Air Leakage Testing and 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. Your ventilation system will operate in a better way Lower levels of mould due to less moisture collecting in gaps and cavities. Thermal comfort is enhanced because air infiltration is lower. 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.


Good and Best Practice Styles

When constructing a new building, it should be built air tight, as stated by Building Regulations – Approved Document L1A. The regulation helps to reduce the use of fuel and power. Part L1A states that any new building must undergo an air pressure test, according to present regulations.

Air Tightness Testing of Dwellings That Meet Technical Standard L1L1

ATTMA has specified technical standards that must be adhered to while testing buildings in the UK, according to 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 a quote on 020 3372 4430
Or you can email us at info@af-acoustics.com

Building Regulation Part L 2010 (England and Wales)

Test for air permeability must be conducted on your new constructions. This is stated in Approved Document L1A. Those exceptions only occur when there are two or more dwellings in a development. Three units of a dwelling type or 50% of all examples of that dwelling type should be tested. 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. Air leakage testing is required on all residential developments (this may be a sample of units) and certain Non-Dwellings. Buildings with a floor area of less than 500 m2 might not have to take the test. Where air tightness testing is not done, an assumed air permeability rate of 15 m3/h/m2 is used.

England and Wales: Building Regulations Part L

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. Its basis is the National Occupation Standard (NOS) and Minimum Technical Competence (MTC) documents standard for testing and essentials for testing knowledge.

Air leakage testers have three levels

  • 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.
  • Level Three: Testing for the air pressure of high rise (LCHR) buildings, phased handover/zonal buildings and other complex buildings is carried out by level three experts.

Report on Test for Air Permeability

Authorised companies, who test buildings of different types, sizes and complexities, give air tightness reports. Extraction fans will be sealed temporarily; the results of the test are recorded in a short report. This is done according to the testing organisation’s procedures and Building Regulation standards.

Air Tightness Test Results

AF Acoustics will ensure the test result is written in accordance with the test standard requirements, identify any deviations from the relevant standards within the report and check air tightness against target value. We make sure our report has the name of the building, customer, address and tester. Where applicable, we will identify pass or failure of your building and provide recommendations for any remedial action or improvement to the building if any further testing is required.

Resources Air Tightness Checklist – Building

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

Air Leakage Pathway Listing – You must ensure the following are properly sealed and don’t have any openings.

  • Windows
  • Metre boxes
  • Extract fans
  • Hoods of cookers
  • Bath panel
  • Hot water tank
  • Chimney
  • Tumble drier extracts
  • MVHR
  • Soil panel
  • Boilers
  • Radiators, fans and heaters
  • Skirting and coving
  • Drainage traps
  • Junction between floor and wall under kitchens and baths

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.