Radlett Air Tightness Testing Certified 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.

The energy performance of a building can be affected by air leakage. To address this problem, alterations to building regulations have been made. Our certificates for air tightness testing are registered with the Air Tightness Testing and Measurement Association (ATTMA), a professional body that focuses on high quality air tightness testing and air permeability applications. We are a dedicated and approved air leakage testing service in Radlett and we can provide air permeability measurement whenever you require. 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.

Because we are ATTMA members, any air tightness certificate we issue shows that the construction has met building regulation standards. 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. 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 is a technique whereby a newly constructed building is evaluated and the quantity of air leaking through is measured. It can also be called air pressure testing or air leakage testing. Air leakage, also known as infiltration or draught, allows air to pass through unwanted leaks in a building; unlike ventilation where the air inside and outside of a building and its flow from one end to the other is controlled. Air tightness testing is done to calculate the total quantity of air that escapes through cracks in the building. Such air leakage is called uncontrolled ventilation (draughts). An excessive amount of uncontrolled air loss results in heat reduction, making the residents uncomfortable. As Government strives to reduce CO2 emissions from new buildings, building regulations now place greater emphasis on reducing air leakage from the building envelope. This reduces fuel consumption and CO2 emissions. With air tightness testing, you can determine whether or not air is leaking from a building’s envelope, the build quality and energy efficiency of new developments. 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. When the building fabric is properly constructed to reduce air loss, the building is economical, and energy efficient.

Air Leakage, what Is It?

This occurs when openings in a building lead to excess air flow into and out of the building. It is not the same as ventilation which is regulated air flowing into a building. It is also called infiltration. 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. Testing for air leakage plays a primary role in determining the energy efficiency of a building. It is an important procedure that measures the air tightness level to ensure that the regulatory standards have been attained and the building’s energy calculations have been properly accomplished. 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. During windy weather, cold air infiltrates a building through the openings in its fabric. This results in heat loss. It doesn’t stop there. Warm, damp air within the building escapes the gaps in its envelope. The air hits the cooler surface in the inner parts of the wall. Water vapour condenses and gathers in these gaps. Eventually, it is absorbed and starts a myriad of defects. The strength of the outer wooden covering is drastically reduced because it is wet.

As the years go by, these conditions can result in structural damage.
Air leakage can also cause these problems:

  • Colder homes that result in discomfort
  • Higher heating expenses
  • Reduction in CO2 emissions’

Successfully managing the movement of air into and outside the building will limit the damaging effects of moisture. Adequately installed air barriers minimise air leaks and the probability of vapour condensing and diffusing into the building’s structure. Correct ventilation is important, whether it is passive or active, to remove water vapour, unwanted moisture odour and pollutants.


Why is an Air Tightness Test Important?

Air tightness is an important factor in a building’s energy efficiency and is part of government’s plan to battle environmental change by regulating the energy performance of buildings. Home heating involves burning up fossil fuel which produces carbon dioxide and aids global warming. The reduction of air leakage leads to lower heat loss and quantity of heat generated in a building. Individuals living in buildings with high levels of air leakage may have medical problems. Houses. Low ventilation and uncontrolled air leaks result in mould growth and moisture which can cause potential health issues. Building tightly and ventilating the right way is highly recommended. Air leakage causes infiltration of moisture into the building envelope, leading to health issues and high repair costs.

When Do I Need an Air Tightness Test?

It is best practice to complete an air tightness test early on and then again at the final stage. 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. 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.

The assessed air permeability of an untested residence is a calculation of the average test score of the same kind of dwelling in the development, increased by 2m3/h/m2 at 50 Pa. Selective testing is not advisable, as it does not give a realistic picture of the air tightness of each individual building. A tested property might be a lot tighter than an untested property. Also, the penalty implemented on the untested houses make air permeability rates very difficult to achieve.

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

AF Acoustics air tightness testing professionalism has helped many homes and business owners in Radlett. We are recommended by our clients for the following reasons.

Expert information and service

Having served many clients in Radlett, we have the expertise to work on any type or size of building. 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 Radlett? Contact AF Acoustics today.

Air Tightness Testing and Measurement Association (ATTMA) Registered

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

Picking a Time for Your Air Permeability Test

We want to provide detailed air permeability testing in Radlett for you whenever you need it. We offer responsive scheduling. Schedule for your building to be tested at your convenience. There won’t be delays or complications once you’ve fixed a time.

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.

Competitive Charges

AF Acoustics fees are lower since we’re a company with low overheads. Our services are professional and we offer affordable prices in Radlett.

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

Air Tightness Testing for Domestic & Commercial Buildings of All Types and Sizes in Radlett

Whatever the type and size of a domestic or commercial building in Radlett, 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 test results are described as The test results are described as m3/h/m2 – (m3 per hour) per square metre..

Air tightness testing is recommended by 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. Too much air leakage leads to heat loss (and consequently, higher CO2 emissions) and discomfort. It can also create convective loops within a building; this is often referred to as thermal bypassing and wind washing. The warm air within a building rises, leading to the influx of cold air through gap, cracks and other openings in the building envelope. The increasing difference in air pressure results in infiltration and exfiltration of air. In Radlett, 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. In addition, you get lower heating and cooling costs. A comfortable environment results in a higher productivity rate.

The Part L Test

Air tightness testing has been a mandatory part of the Building Regulations for new build and refurbishment projects since Approved Document L was revised in 2006. Air tightness can also be called air leakage 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. 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. The maximum air permeability rating allowed is 10m3/h/m2, but your building might need a lower rating ts. Air permeability is key in the following areas: i. A construction’s energy performance, ii. CO2 emission targets iii. Building Regulations Part L standards

Part F Test

We will help you with all your Parts L and F requirements. In addition to conducting your air pressure test and extract fan flow rate testing, we can put you in contact with professionals who provide SAP calculations, Energy Performance Certificates, and water calculations.
According to Part F, it is compulsory for a flow rate test to be conducted on all mechanical extract fans of new buildings. Evidence of this test must be passed to the Building Control Body (BCB) as part of their sign-off procedure. 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.


Different Ways We Test for Air Permeability

The size, type and multifaceted parts of a building determine the level of air pressure testing it will receive. There are 3 levels and they are listed below. A single blower door fan is the instrument used for the first level to examine single buildings and smaller non-dwellings from 1m3 to 4000m3. The second level examines simple and complex buildings greater than 4000m3, with the exclusion of large zonal buildings and complex high rise (LCHR) buildings. Level 3: Air Pressure Testing for LCHR buildings, phased and zonal handover buildings is carried out.

Domestic Buildings Testing as Required by Approved Document L1

Air tightness testing determines the extent of air leaking out a building’s envelope. The result is written as m3/h/m2 – (m3 per hour) per square metre of building envelope. Air tightness testing is required for new builds. In order to comply with the carbon emission target, it is necessary to achieve a lower air permeability rate. The required air permeability rate for a dwelling can be found on the design-stage SAP report for that dwelling. An excessive amount of air leakage results in greater energy expenses, heat reduction and carbon dioxide emissions.

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

Air pressure testing involves the calculation of air escaping through the openings in a building. The result is expressed as a quantity in the form of air pressure (m3 per hour) per square metre of building fabric. Document L2A of Building Regulations declares air leakage testing to be mandatory. The test results have a limit; they shouldn’t be higher than 10m3/h/m2. A building will usually have to achieve a lower rate to meet the SAP or SBEM assessment. The air permeability target can be found in a building’s design-stage SAP or SBEM assessment. An excessive amount of air leakage leads to greater energy expenses, heat reduction, carbon dioxide discharge and draughts.

Testing the Smoke Shaft of Automatic Opening Vents

To ensure that the auto opening vent will perform optimally when fitted and commissioned, we test the smoke shaft to verify its air tightness. 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 the vents and fans to operate at the expected level, the smoke shaft must be air tight to create a difference in air pressure and give emergency services when needed. To ensure that automatic opening ventilations work properly, their manufacturers have placed an air permeability target for them which we work towards. An air pressure test is conducted using a fan installed in the shaft. 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

Buildings that are well insulated and air tight are the standard for buildings. As a result, a high-quality ventilation system that is adequate and performs as required is vital. We are able to test extraction rates. A building must have an optimal ventilation system to dispel humidity from bathrooms, kitchens and other rooms and extract odours and pollutants. We can also help you meet the Building Regulations targets. 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.

Explicit Test and Building Preparation Process

When a building is checked for the quantity of air flowing through the gaps in the fabric, it has undergone an air tightness test. If the rate of air pressure is good, the energy performance of a building will be high and the inhabitants will be comfortable.

Holes and spaces in a building’s fabric might be hidden by the internal building finishes, making them hard to find. The best solution to demonstrate a building’s air tightness level is to check for leakage paths in the building envelope.

Under the new regulations developers must test 20% of the dwellings on a site but this also depends on the amount of differing house types to ensure that a consistent sample is taken throughout the construction of the development. Buildings that don’t undergo the test are penalised. All dwellings in a development should be tested to ensure optimum air tightness.

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. The duration of air pressure testing is 30 to 60 minutes in most cases and the wind speed should not be more than 6m/s. Test engineers need the drawings and air permeability details from clients so that they can know the size of the building envelope and other information before arriving at the building. 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

Building Envelope Calculations

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 calculations, which are extracted from the drawings, are fed into our estimations when testing your building for air leaks.

Air Barrier Envelope Area

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 Change Rate

Air exchange rate is vital to ventilation design but it isn’t used as the determinant of the actual design or calculation. Residential ventilation rates are calculated based on area of the residence and number of occupants.

Measuring a Cold Roof Construction’s Envelope Area

This is essential to determine if the roof area is the same as the ground floor area. A cold roof is the kind of roof where the insulation is fixed in the ceiling joists with space between the insulation and roof rafters.

Evaluating a Warm Roof Envelope Area

A warm roof has the insulation running along the pitched roof rafters with an air barrier normally running parallel along the inside face of the insulation. The envelope area, found at the insulation’s warm side, is the separator between the conditioned internal aspect and the unconditioned.

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);

Building Test Method

Examine the wind speed, barometric pressure 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. Increase the speed of the fan slowly till it gets to 55-60Pa. Record pressure differences across the building at each fan speed.

Air Leakage Measurement

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

A low leakage building that is properly ventilated, whether natural, hybrid or mechanical, is very beneficial. The benefits are: Lower energy costs and need for heating appliances due to a higher level of heat retention. A functional ventilation system Less mould will be trapped in the building fabric as a result of less moisture. Fewer draughts and enhanced 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 Radlett.


Best Practice Processes

All new buildings, residential or commercial, must be air tight, according to Approved Document Part L1A of Building Regulations (2010). The regulation is focused on the conservation of fuel and power usage. Part L1A states that any new building must undergo an air pressure test, according to present regulations.

Testing for Air Permeability on Building Fabrics, According to L1 Technical Standard.

Certain technical standards are to be employed during air pressure test in the UK, as specified by ATTMA, building regulations and other documents. They explain in detail and provide guidelines for 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”.

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. Where there are two or more new buildings in an area, conduct a test on 50% of all examples of a kind of dwelling or 3 units of a dwelling kind. If there are no more than two new dwellings, using an assumed value of 15m3/h/m2 in the DET/TER calculations might exempt them from air tightness testing. Find out from your SAP assessor if this is applicable to you. The required process for testing buildings for air tightness has been declared in ATTMA TSL1 for occupied buildings and ATTMA TSL2 for unoccupied ones. Air tightness tests are to be carried out on all residential developments (all the buildings or a selected group) and all certain Non-Dwellings. If your building has added an estimated assessed rate of 15 m3/h/m2 in its calculations or its useful floor space is less than 500 m2, it may not have to take the test.

Building Regulation Requirements Part L (England and Wales)

ATTMA has a scheme for air leakage test organisations, which commenced in January 2015. The scheme was approved by the government and is stated in Technical Standard L1 and L2. Minimum Technical Competence (MTC) and National Occupation Standard (NOS) documents are the basis for the scheme.

Air tightness testers can be divided into three categories

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

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. This is done according to the testing organisation’s procedures and Building Regulation standards.

Test Outcomes

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 will ensure the report correctly identifies the tester, customer, building and its 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 – Dwelling

Go through the list below and send the design air testing permeability value to us before we get to the site.

Air Permeability Pathway List – We will inspect every part for the building envelope for leaks.

  • Windows: Examine the seal below the sills and around the frames.
  • Doors: Inspect the seal around all external door surrounds. This is more applicable to French doors.
  • Drainage traps: Make sure they’re not filled with water.
  • Skirting and coving: Examine every part and seal where needed.
  • Meter Boxes: Make sure the external supplies are properly covered.
  • Light Fittings: Inspect the seal around all light fittings and switches.
  • Radiators/Fans /Heaters: Check the seal on pipes and wires.
  • Boilers: Inspect the seal around the boiler supply and flue.
  • Extractor Fans: Inspect the edge of the extracts and seal the front of the grill.
  • Cooker Hoods: Examine the seals around all penetrations.
  • Soil pipes: Inspect the seal around all soil pipes and sink waste pipes especially those inside or behind kitchen cupboards.
  • Bath Panels: Make sure all the pipes behind bath panels are sealed properly.
  • Hot water tank: Examine the seal around supply pipes.
  • MVHR: Examine seal around all terminals.
  • Chimneys: Cover the open fireplaces.
  • Junction between floor and wall under kitchens and baths
  • Tumble drier extracts: Study the seal around the extract.

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.