ATTMA Licensed Air Tightness Testing in Stevenage

Air tightness testing, also known as air leakage testing or air permeability testing, establishes the rate at which air flows out of gaps in a building fabric. It has been a mandatory part of the building regulations for new build and refurbishment projects since Approved Document L was revised in 2006.

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. As a certified air leakage testing company in Stevenage, we are ready to provide testing services whenever you want. 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.

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. Not only do we test the air permeability of your building, we describe the procedure in a professional manner and advise you on problem areas discovered during the evaluation. We deliver professional value for money service to the highest standards.

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

What is the Assessment of a Building’s Air Tightness?

Air tightness testing is a technique whereby a newly constructed building is evaluated and the quantity of air leaking through is measured. It is sometimes referred to as air leakage testing or air pressure 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. Air tightness testing is the recognised method used to measure total air lost through leaks in a building fabric. This is often referred to as uncontrolled ventilation (draughts). An excessive amount of uncontrolled air loss results in heat reduction, making the residents uncomfortable. 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 important in establishing air leakage from a building’s fabric, the energy efficiency of a new building and in identifying poor build quality within new developments. With the introduction of tougher regulations, building designs will often consider air tightness at the early stages of the construction process, ensuring attention to detail during construction to create an air-tight envelope. 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 Explained

This occurs when openings in a building lead to excess air flow into and out of the building. When the circulation of air is properly monitored and bridled, ventilation has occurred. Another name for air leakage is infiltration. Once the atmosphere is windy, draughts infiltrate the building through holes in the fabric, leading to heat reduction and discomfort. 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.

The Impact of Air Leakage

Heat loss within a building can be caused by air leakage. During windy or cold weather, the infiltration of uncontrolled air through cracks in a building envelope occurs, leading to heat reduction. The infiltration of chilly air causes exfiltration, making warm air within the building escape through the spaces in other parts of the building. The warm air is filled with moisture, which hits the inner wall surface and condenses. Moisture is sucked into the building material, and this can lead to serious structural issues. The strength of the outer wooden covering is drastically reduced because it is wet.

Over time, any of these conditions can cause structural damage.
The inhabitants become uncomfortable because of chilly homes, heating expenses increase and more CO2 is emitted due to the additional heat required.

These effects can be mitigated by controlling the circulation of air into and out of the building. An adequately installed air barrier reduces air leakage and condensation of water vapour on inner wall layers. Correct ventilation is important, whether it is passive or active, to remove water vapour, unwanted moisture odour and pollutants.


Why Must We Do 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. Properties with uncontrolled air leakage also cause health issues. A building with poor ventilation and high air permeability is conducive for moisture and mould growth which can affect the inhabitant’s health. Building tightly and ventilating the right way is highly recommended. 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

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 results of the test are used in SAP and SBEM calculations, and can influence a building’s overall energy rating. 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. With selective testing, you get a penalty of +2m3/h/m2. Houses that have a target score of 5m3/h/m2 must get a lower score of 3.

Where the dwelling has not been pressure tested, the assessed air permeability is the average test result obtained from other dwellings of the same dwelling type on the development, increased by +2.0 m3/h/m2 at 50 Pa. Selective testing is not recommended because: i.It is quite tough to achieve the lower air permeability rate set for untested dwellings. ii.The proper air tightness rate for each building in the development cannot be attained, as only some underwent air tightness testing; a tested building might be much tighter than an untested one.

Why Choose AF Acoustics for Your Air Tightness Testing?

At AF Acoustics, our air tightness testing expertise has helped many home and business owners in Stevenage. We are recommended by our clients for the following reasons.

Helpful service and information

Our vast experience in serving a variety of clients in Stevenage guarantees we have the expertise to satisfy your needs regardless your unique circumstances, type or size of property. 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. Do you need trustworthy professionals who will provide great results in Stevenage? Contact AF Acoustics today.

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

We are registered members of the ATTMA, a professional association dedicated to promoting technical excellence in air tightness testing and air leakage measurement applications. This means our expertise and quality of services are recognised by the leading air tightness testing body in the UK.

When to Call Us to Test Your Building

Our comprehensive air permeability testing in Stevenage is available. We offer responsive scheduling. Schedule for your building to be tested at your convenience. We guarantee no delays or complications regarding scheduling.

You Could Get Your Certificates on the Next Day

AF Acoustics has professional speedy services to satisfy clients who want their test results immediately. We have a next day turnaround policy for our test certificates and endeavour to deliver in all situations.

Affordable Fees

AF Acoustics offers competitive fees in Stevenage. 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 Stevenage

We conduct air permeability tests on residential and commercial buildings of all sizes and types. After the test, an ATTMA certificate is given to you. Air permeability testing calculates how much air moves through spaces in your building’s fabric. The results are registered as The test results are described as m3/h/m2 – (m3 per hour) per square metre of building.

Air leakage testing is a requirement of Approved Document L1A and L2A. A maximum air permeability rate of 10m3/h/m2 is required. However, a building has to achieve a lower rate to meet the carbon emission target. To get your building’s required air permeability rate, check its design-stage SAP assessment SBEM. Several problems are caused by uncontrolled ventilation. They are:

  • Infiltration of cold air
  • Wind washing and thermal bypassing, which is when air moves through the inner building of a building fabric to create convective loops inside the walls, making the building less energy efficient
  • Reduction in heat and CO2 emission.

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. Air tightness testing is required by law for domestic buildings to ensure energy efficiency and comfort within the home environment. It is also a legal requirement that all new builds have an air tightness test carried out to meet energy efficiency standards before it can get signed off by building control in Stevenage. 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.

The Part L Test

Air tightness testing is a Building Regulations obligation for new buildings, commercial developments and revamped buildings. This was put into effect in 2006 after Document L was reappraised. Air tightness can also be called air leakage or air permeability 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. Part L has also set a maximum air permeability target rate of 10m3/h/m2, but a building usually needs lower levels. Air leakage is vital to a building’s energy efficiency and is needed to meet Building Regulations Part L and carbon emission standards.

What Is Part F Test?

We can provide you all that you need to serve all your Part L and Part F requirements. Not only will we conduct your air tightness test and extract fan flow rate test, we will also recommend experts who can handle your SAP calculations, water calculations and Energy Performance Certificates satisfactorily.
New buildings should ensure that all mechanical extract fans are tested for flow rate, as stipulated by Part F of the Building Regulations. Your building won’t be signed off until Building Control Body (BCB) has been presented the results of the test. Examining, documenting and submitting reports of extract fans’ test can be done using three methods. AF Acoustics employs the minimum benchmark procedure (method 3), which involves using a vane anemometer.


Types of Air Leakage Testing Services We Offer

Air Tightness Testing has different tiers, depending on how complex a building is and its size. Find them below: Level One: Testing for the air pressure of single buildings and smaller non-dwellings of 4000m3 gross envelope volume and below, a single blower door fan is used. Second Level – Testing is done for building 4000m3 and higher, typically simple and complex dwellings. High rise and phased handover buildings are not part of this test. The third level tests big and complex zonal and phased buildings and complex high rise buildings.

Approved Document L1 Air Pressure Testing of Houses

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. Document L1A of Building Regulations declares air leakage testing to be mandatory. Your building may need a lower rate to meet the CO2 discharge target. The required air permeability rate for a dwelling can be found on the design-stage SAP report for that dwelling. Excess air leakage causes heat loss and discomfort due to the influx of cold air, also causing increased energy bill expense.

Testing of Air Permeability of Commercial Dwellings, in Accordance with Document L2 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 test results are inscribed using m3 per hour per square metre. Air tightness testing is required by Building Regulations. The highest air permeability rate for your dwelling when tested should be 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.

Air Leakage Test of Smoke Shafts for Auto Vents

Smoke shaft needs to be tested because its air tightness determines the performance of the automatic opening vent fitted on it. Our professionals perform the test. 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 fans and vents to perform as required, the shaft itself must be sufficiently air tight so as to create the pressure difference to draw smoke out of the building and protect the occupants. 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. Once the test is completed and successful, the automatic opening vents are installed.

Domestic Ventilation Air Flow Testing (Extract Fans)

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 have the capacity to test extraction rates. It is important to ensure the ventilation strategy is working effectively. This helps to remove pollutants from the air and control excess humidity, particularly in rooms such as bathrooms and kitchens. Building Regulations Part F also requires that the air flow test of all extractor fans (such as kitchen and bathroom extract fans) in new buildings to be conducted and results given to Building Control before construction ends.

Particular Test and Building Readiness Operation

An air tightness test measures the extent of air leakage in a building. Improving the air tightness of a building not only enhances the comfort of the occupants, but can also increases the building’s energy efficiency.

It is difficult to notice unwanted openings in a building envelope. They might be blocked by the internal finishes. The best solution to demonstrate a building’s air tightness level is to check for leakage paths in the building envelope.

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 advise that all buildings undergo air pressure testing as there is a penalty for those that don’t.

Requirements before the Test

Our test engineers would like to see the drawings (plans and elevations) and design air permeability requirements of your building before taking the test. We would like to know the requirements and the building envelope’s size prior to testing. The tests take 30 – 60 minutes, and wind speed does not surpass 6m/s. An air tight environment should be created in your building before the test to ensure optimal results. Do the following:

  • Shut the windows
  • Close the smoke vents
  • Open and secure all inner doors
  • Put off the mechanical vents
  • Close ventilation
  • Fill drainage traps
  • Put off range cookers/stoves a day before the test (if applicable)

Measuring the Building’s Envelope

We undertake the building envelope calculations before we arrive on the site. 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.

Envelope Area Air Permeability

Approved Document L1A Conservation of Fuel and Power in New Dwellings (2010) defines air permeability as “air leakage rate per hour per square metre of envelope area at the test reference pressure differential of 50 pascals (50n/m2)” and envelope area as “the total area of all floors, walls and ceilings bordering the internal volume that is the subject of the pressure test. This includes walls and floors below external ground level. Overall internal dimensions are used to calculate this envelope area and no subtractions are made for the area of the junctions of internal walls, floors and ceilings with exterior walls, floors and ceilings.”

Air Exchange Rate

Although hardly used as a major deciding factor for calculation or design, air exchange rate is vital in ventilation design. The number of inhabitants and area of residence are used in measuring residential ventilation rates.

Calculating the Envelope Area of a Cold Roof

The area of the roof and ground floor should be the same. A cold roof has its insulation at the ceiling level, with space between the insulation and rafters.

Calculating the Envelope Area of a Warm Roof

In a warm roof, the main insulation is placed below the roof covering. The envelope area is the barrier between the conditioned space in the insulation and the unconditioned space outside.

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

Measure the weather conditions. Check the temperature, barometric pressure and wind speed. Place the fan on an aperture within the building envelope. Set up the equipment for air tightness testing. Record the air volume flow through the fan (this equals the air leaking through the building envelope). Slowly raise the fan speed from 20-25Pa to 55-60Pa. Record pressure differences across the building at each fan speed.

Air Leakage Measurement

Our competent engineers note the points of air leakage, examine the test data and send test results to the customer in a technical report. If the test fails, we inform clients on what to do about it. Air Tightness Testing and 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: Lower heating bills due to less heat loss, with potentially smaller requirements for heating and cooling equipment capacities Better ventilation system Lower levels of mould due to less moisture collecting in gaps and cavities. Fewer draughts, causing more comfort 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 Stevenage.


Good and Best Practice Styles

Any new building has to be air tight. The 2010 Approved Document L1A of Building Regulations has made it compulsory. The regulation is focused on the conservation of fuel and power usage. Part L1A states that new dwellings should be tested for air tightness in accordance with existing regulations.

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

There are technical standards for air tightness test of buildings in the UK detailed by Air Tightness Test and Measurement Association (ATTMA). The technical standards give details regarding the following: 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”. That way, testing companies use the same method.

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

Undergoing an air tightness test is compulsory for your new building, according to Part L of Building Regulations. For development with two or more buildings, three units of each dwelling type or 50% of the 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. To find if your building falls into this category, contact your SAP assessor. There are different ways that Dwellings and Non-Dwellings should be tested. ATTMA TSL1 and ATTMA TSL2 have clearly stated these. Air leakage testing is required on all residential developments (this may be a sample of units) and certain Non-Dwellings. 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.

Building Regulations for England and Wales, Part L

Most competent air pressure testing companies go through the ATTMA scheme, which began in January 2015, etence. The scheme is endorsed by the government and recognised by approved documents L1 and L2 of building regulations. It is based on the performance criteria and knowledge requirements set out in the suite of National Occupation Standards (NOS) and under the requirements of the Minimum Technical Competence (MTC) document.

Air pressure 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.
  • Second Level – Testing is done in buildings with 4000m3 and higher. Large high rise and phased handover buildings are excluded from the test except a level three tester is in charge.
  • 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.

Air Leakage Test Report

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. The report adheres to the company’s methods and all standards and requirements of Building Regulations.

Air Tightness Test Results

AF Acoustics guarantees the test outcome is written in line with standard requirements; it picks out any deviations from the significant benchmarks inside the report and checks air permeability against target values. We make sure our report has the name of the building, customer, address and tester. Where it’s needed, we will identify if your building passed or failed the test and suggest ways to repair the building envelope before a retest is done.

Resources Air Tightness Checklist – Building

Before we arrive on site, ensure you have sent us the air permeability target and been through the checklist below and the ones we have sent you. This will greatly facilitate the process.

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

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.