HenleyonThames Air Tightness Testing, Licensed by AF-Acoustics

Air tightness testing, also called air leakage testing or air pressure testing, calculates the quantity of air escaping through openings in a building. 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. 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. Located in HenleyonThames, our company is a committed and accredited air permeability testing service provider; we provide air testing services. You can also contact us for assessments and consultancy services. In addition to air leakage testing, we provide Part F Mechanical extract fan flow rate testing.

As registered members of the ATTMA, our air tightness certificates are accepted as proof of building regulations sign-off. We are professionals who take the time to explain the testing process, we are able to give informed advice on where problem areas may occur during testing, and how improvements can be made based on results of air pressure testing. Our customers get greater value for money spent, and our testing services are of superior quality.

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 – What Does It Mean?

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. While the normal restrained movement of air all through a building is called ventilation, the unchecked movement of air through cracks and gaps in a building is air leakage; also known as draught or infiltration. Draughts are uncontrolled ventilation. Using air tightness testing, the total air lost can be estimated. Too much air leakage leads to unnecessary heat loss and discomfort for the occupants. Because the government is striving to scale back carbon dioxide discharge from new buildings, building rules now focuses on reducing air loss from the building envelope. This helps reduce CO2 emissions. Air tightness testing is a crucial activity that

  • shows the air leaking from gaps in a building.

The building regulations have made air tightness part of the building’s design from the beginning of the construction. This ensures that the fabric of a building is air tight. This can make a building more energy efficient since air leakage is under control. It will also be cost effective and of high quality.

Air Leakage, what Is It?

Air leakage occurs when air escapes through holes and gaps in a building. It is also referred to as infiltration and is the opposite of ventilation which involves well managed circulation of air in 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. Air leakage testing plays a significant role in the energy-saving efficacy of properties. With air tightness testing, you can be sure that the building has met the stipulated targets used for energy calculation and air tightness. In 2006, air tightness of newly constructed buildings and non-dwellings with a floor area over 500m² became compulsory in England and Wales.

The Impact of Air Leakage

When air escapes uncontrollably from a building, heat reduction occurs. Heat loss is caused by influx of frosty outside air into a building through the openings in its envelope during draughts and cold weather, leading to an uncomfortable drop in temperature. As cold seeps inside, warm moist air escapes through the cracks and gaps in the building. Some of it settles within the building’s fabric. Once the moist air reaches the colder internal layer of the wall structure, the vapour in it condenses and forms droplets of liquid, which drawn into building materials and can potentially start a multitude of structural problems. There could be a decrease in the toughness and solidity of wet wooden covering due to rot.

These problems will eventually cause structural harm to the building.
Other effects of air leakage are:

  • Discomfort; the environment is colder
  • Higher heat cost; a way of combating the cold, and
  • More CO2 emission because of the extra heat used.

These effects can be mitigated by controlling the circulation of air into and out of the building. The potential of vulnerable wall structures to absorb condensed moisture is reduced when air barriers are properly installed and uncontrolled air flow is reduced. Proper ventilation, whether active or passive, is critical in expelling undesirable damp scents, water vapour and polluting substances.


Why You Should Conduct an Air Tightness Test

Climate change caused by carbon dioxide emission is an environmental hazard that government is trying to curb. Energy performance and air tightness is a key part of this plan. Heating buildings involves burning fossil fuel which increases CO2 emissions and causes global warming. A reduction in air leakage lessens the heat needed to keep a building warm. There are also health issues associated with uncontrolled air leakage. When a building has poor levels of controlled ventilation and high levels of uncontrolled air leakage, this can cause excessive moisture and mould growth, leading to poor health. Best practice advice is to “Build tight, ventilate right”. 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 Your Building Needs an Air Tightness Test

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. 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.

buildings that have not been tested are assessed for air permeability based on similar dwellings’ test scores +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?

At AF Acoustics, our air tightness testing expertise has helped many home and business owners in HenleyonThames. Because of the following guarantees of working with us, we are highly endorsed by our clients.

Service and knowledge

Our experience in serving diverse customers in HenleyonThames 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 HenleyonThames.

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

AF Acoustics is a member of ATTMA, an association of specialists that concentrates on promoting the best air tightness measurements and air permeability testing techniques. It is the leading air permeability testing body in the UK and has recognised our competence and services.

Scheduling Your Air Tightness Testing

We want to provide detailed air permeability testing in HenleyonThames for you whenever you need it. We offer responsive scheduling options. You can schedule for air tightness testing at your convenience. There won’t be delays or complications once you’ve fixed a time.

Next-day Turnaround on Test Certificate Where Possible

AF Acoustics offers trustworthy and expert services. We know that clients want to receive their test results quickly. As a result, we endeavour to deliver test certificates by the next day.

Affordable Fees

AF Acoustics offers competitive fees in HenleyonThames. Since we’re a small business, we offer less expensive air permeability testing and render high quality services.

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

Air Permeability Testing for Different Kinds of Commercial and Domestic Dwellings in HenleyonThames

Whatever the type and size of a domestic or commercial building in HenleyonThames, AF Acoustics’ experts can test it for air permeability and issue an ATTMA certificate afterwards. The best way to determine how much air seeps through a building’s fabric is through air permeability testing. The results are written as The test results are described as m3/h/m2 – (m3 per hour) per square metre. of a building envelope.

Air leakage testing is a requirement of Approved Document L1A and L2A. 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. Infiltration/exfiltration is the effect of air pressure difference. Warm air rises while cold air falls. The warm air within a building rises and air pressure at the base falls; this results in air coming in through doors, windows and leakage points. In HenleyonThames, the law demands that all new buildings be tested for air pressure before they can be approved and signed off by building control. This enables dwellings achieve energy efficiency standards. Clients and employees will be at ease in their surroundings. It will also help you reduce the cost of maintaining heating or cooling in your commercial building, making it more productive.

Part L Test Explained

In 2006, Approved Document L was reviewed and building regulations for air permeability became tighter. The air tightness test is presently a requirement for new buildings and reconstructions. The air-tightness of a building is known as its ‘air permeability’ or leakage rate. Air leakage can happen via holes and splits in the texture of the building envelope (divider/rooftop sections, service penetrations, etc), which may not be obvious. The Building Regulations (Part L) demand that a selected group of different kinds of residential constructions and all non-domestic buildings greater than 500m2 perform air leakage tests. To adhere to Part L, make sure your building’s air permeability rate is not greater than 10m3/h/m2. Air leakage is vital to a building’s energy efficiency and is needed to meet Building Regulations Part L and carbon emission standards.

A Description of Part F Test

We can complete all your Part F and Part L testing requirements. We deliver quality air permeability and extract fan flow rate testing, and also recommend skilled experts who will handle your water calculations, SAP calculations and Energy Performance Certificates.
Approved Document F of the Building Regulations demands that all mechanical extract fans in newly completed constructions undergo a flow rate test. Evidence of this test must be passed to the Building Control Body (BCB) as part of their sign-off procedure. There are 3 available methods for examining, recording and reporting the testing of extract fans. 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: First Level – For building 1m3-4000m3, single and smaller non-dwellings, a single blower door fan is used to carry out the test. Level 2: Air pressure testing for simple and complex buildings larger than 4000 m³ gross envelope volume which does not include large and complex, high rise (LCHR) buildings, and phased handover/zonal buildings. Third Level – Testing is done for large high rise and phased handover buildings.

Air Tightness Testing of Houses and Flats to Meet Approved Document L1

Air pressure testing, involves the calculation of air escaping through openings in a building. The test results are inscribed as m3/h/m2 – (m3 per hour) per square metre. Part L1A of Building Regulations stipulates that such tests be conducted. A lower air permeability rate might be needed due to carbon emission requirements. To get your building’s required air permeability rate, check its design-stage SAP assessment SBEM. Too much air leakage leads to heat loss which can lead to draughts and higher energy bills.

Approved Document L2A Air Pressure Testing of Commercial Constructions

Air tightness testing determines the extent of air leaking from a building’s envelope. The result of the air leakage test is expressed as a quantity of air leakage (m3 per hour) per square metre of building envelope. Air tightness testing is required by Building Regulations. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. The result of your dwelling’s air permeability rate might have to be lower than required due to SAP or SBEM assessment. The air permeability target can be found in a building’s design-stage SAP or SBEM assessment. Too much air leakage leads to heat loss (and consequently, higher CO2 emissions) and draught.

We Test Your Automatic Opening Vent’s Smoke Shaft

We undertake smoke shaft integrity testing to confirm that the shaft is sufficiently air tight in order to allow the automatic opening ventilation to perform as required when it is fitted 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. An air tight shaft creates sufficient pressure difference and ensures that the fans and vents perform properly to draw out smoke from a dwelling and save its occupants. We work towards air permeability targets set by the automatic-opening ventilation manufacturers that allow their equipment to operate effectively. An air pressure test is taken for the smoke shaft by installing a fan inside. 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. Once the test is completed and successful, the automatic opening vents are installed.

Air Flow Measurement of Domestic Ventilation (extraction fan testing)

The mandate to construct well insulated and air tight buildings, has made it crucial for satisfactory, enhanced and balanced ventilation systems to be installed. We have the capacity to test extraction rates. This test is required by law and it enables a building have a high-quality ventilation system that is efficient and removes pollutants and odours while limiting humidity in rooms, 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.

Specific Test and Building Preparation Procedure

The measurement of air pressure in a building is known as an air tightness test. The air tightness of a building improves its energy efficiency and internal environment.

It is difficult to notice unwanted openings in a building envelope. They might be blocked by the internal finishes. If you know the leakage paths of a building, you will know if it is air tight.

With residential buildings in an area, new building regulations demand that a minimum of 20% be measured for air leakage. Consistent samples are determined by the quantity of the different types of houses present during the construction of the project. Buildings that don’t undergo the test are penalised. All dwellings in a development should be tested to ensure optimum air tightness.

What Should You Do Before Testing Your Building?

Clients should send the drawings (plans and elevations) and air permeability requirements to our engineers. 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:

  • Open and secure all internal doors;
  • Close all windows;
  • Switch off all mechanical ventilation systems;
  • Seal ventilation;
  • Close smoke vents;
  • Fill all drainage traps;
  • Switch off all range cookers/stoves 24 hours before testing (if applicable)

Measuring the Building’s Envelope

We take the building envelope calculations before the test. The building envelope is the surface area of the thermal boundary of the building. We use the building envelope measurements to get the right results when testing for air tightness.

Air Barrier Envelope Area

Air permeability is measured as air leakage per hour per square metre of the building fabric at a pressure differential of 50 pascals (50n/m2). The air barrier envelope area is the total area of all the floors, walls and ceilings both above ground and underground. The internal dimensions of the building found in the drawings are used to calculate the envelope area and subtractions are not made from the areas of floors and ceilings with or without external walls or from the area of the junctions of internal walls.

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. Residential ventilation rates are measured based on the number of inhabitants and area of residence.

Evaluating a Cold Roof Envelope Area

The area of the roof and ground floor should be the same. A cold roof is a roof that has its insulation in the ceiling and there’s a huge space between the insulation and rafters.

Warm Roof Construction Envelope Area Calculation

In a warm roof, an air barrier is inside the insulation which runs on the pitched roof rafters. 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.

Preparing the Building

  • Shut all windows
  • Close the smoke vents
  • Shut and secure all inner doors
  • turn off the mechanical vents
  • Temporarily seal vents
  • Fill and block drainage traps

How the Test Is Done

Evaluate the weather (barometric pressure, wind speed and temperature) Place the fan on an aperture within the building envelope. Ensure all the testing equipment is ready. 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. Note the difference in air pressure in several parts of the building at each fan speed.

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 Pressure Testing & Compliance

When a building has the right kind of ventilation (mechanical, natural or a combination of both) and has a low permeability rate, the advantages to the occupants are numerous. Some of them are: The occupants will pay less for heat because less heat is lost and they won’t need equipment with high heating capacities. Your ventilation system will operate in a better way Lower probability of mould because moist air won’t condense in the openings in the building envelope. You won’t experience much discomfort because there will be fewer draughts. Be assured that you’ll get a test that meets all the regulations and standards no matter how big or small your building is. We render cost-effective services that include air leakage tests, design reappraisal, consultancy and support services for dwellings and non-dwellings in HenleyonThames.


Good and Best Practice Styles

Building Regulation Part L1A 2010 stipulates that all new buildings must have low air permeability. Reduced power usage and fuel conservation are important; that’s why the rule was put in place. Part L1A states that any new building must undergo an air pressure test, according to present regulations.

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

Certain technical standards are to be employed during air pressure test in the UK, as specified by ATTMA, 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 for England and Wales, Part L 2010

If you are constructing a dwelling the Approved Document L1A states that you must perform an air pressure test. 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. Your SAP assessor will be able to confirm if this is the case for your dwelling. The method for testing required by the building regulations is stated 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. A building might not have to undertake the air leakage test if its floor space is less than 500m2 or its DET calculations have an air permeability rate of 15 m3/h/m2 added to it.

Part L Building Regulations Standards for 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. 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

  • Level One: Testing for the air pressure of single buildings and smaller non-dwellings of 4000m3 gross envelope area and below, is done with a single fan.
  • Level Two: Testing for the air pressure is done in all single and multifaceted buildings. High rise (LCHR) buildings and phased handover/zonal buildings are excluded from this level, except a level 3 tester is in charge of the team.
  • The third level expert tests big and complex zonal and phased buildings and complex high-rise buildings.

Air Tightness Test Report

Authorised companies, who test buildings of different types, sizes and complexities, give air tightness reports. First, extraction fans are closed. Then, the details and results of the tests are written down in a report. The organisation makes sure the report meets the company and government’s requirements.

Results of the Test

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. Our reports correctly note the client, air tightness tester, building and address. We will state if your building has passed or failed the test and give advice on the actions you need to take if another test is needed.

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 Permeability Pathway Checklist – Use this checklist to make sure you are ready for the test. Ask yourself, “Have I sealed any visible opening?” Check the following appliances.

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

We Provide Temporary Sealing – the following should be temporarily sealed during the test;

  • Trickle Vents: Should be closed.
  • Extractor Fans / MVHR terminals: All extracts should be temporarily sealed (Please ensure these are off before sealing).
  • Cooker Hoods: Should be sealed from the outside or inside.
  • Chimney Flues and Air Bricks: Should be temporarily sealed.

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.