Air Tightness Testing, Certified by AF-Acoustics, in Rayners-Lane

The measurement of air escaping from a building is called air tightness testing. It is also referred to as air permeability testing or air pressure testing. Air tightness testing has been a compulsory part of the building regulations for new dwellings, renovations and commercial projects since the revision of Document L in 2006.

The energy performance of a building can be affected by air leakage. To address this problem, alterations to building regulations have been made. Our Air Tightness Testing certificates are registered with Air Tightness Testing and Measurement Association (ATTMA), a professional association dedicated to promoting technical excellence in all air tightness testing and air leakage measurement applications. We are dedicated and accredited air leakage testing service providers in Rayners-Lane and we are available to provide you with testing services whenever required. You can also call or email us for any of these services:

  • Assessments
  • Consultancy
  • 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 don’t just provide air tightness testing. We describe the process thoroughly, give expert advice on areas that could be problematic during testing, and suggest improvements based on the air permeability rating of the building. 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 It Means

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 should not be confused with ventilation. Also called draughts or infiltration, air leakage is unrestrained movement of air through holes in a building fabric, while ventilation is the restrained and planned movement of air. Air 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). When too much air leaks through a building’s fabric, heat loss occurs, making the occupants uncomfortable. Air leakage from buildings causes heat loss, more energy is then used to keep the building warm, this is a cause of excess CO2 emissions. This has resulted in regulations which are centred on decreasing air leaks from the building fabric, therefore lowering CO2 emissions. Calculating the emission of air from a building’s fabric, establishes the energy efficiency of the building. The introduction of tougher regulations has led to the construction of high-quality buildings. Building designs employ air tightness procedures from the early part of construction, creating a building that has adequate air tightness built into its design. Understanding this at an early stage can make a build cost-effective, of high quality, and energy efficient by minimising uncontrolled air leakage.

Air Leakage

This occurs when openings in a building lead to excess air flow into and out of the building. Also called infiltration, it differs from ventilation which is the regular, planned and restrained flow of air into a building. It leads to heat deprivation when cold draughts happen and warmth is needed the most. Because air leakage is uncontrolled ventilation, excessive air flows into the house during windy and wintry weather. Air leakage and a dwelling’s energy efficiency are intertwined. Testing is needed to verify that air tightness levels used in the building’s energy calculations align with the targets required by the law. In England and Wales, air tightness testing has been mandatory since 2006 for all new builds and non-dwellings with a floor area over 500m².

The Impact of Air Leakage

Air leakage causes heat loss. 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 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. Wet wooden overlay or framing can decay, decreasing its durability.

Over the years, these problems can damage the building’s structure.
The inhabitants become uncomfortable because of chilly homes, heating expenses increase and more CO2 is emitted due to the additional heat required.

The most effective method of lessening the damage caused by moisture is to control the flow 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. 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

The energy performance of a building is determined by how air tight it is. Energy performance affects CO2 released from buildings. As a result, air tightness testing is a method government has devised to regulate climate change. Environmental change caused by carbon dioxide emissions and global warming is partly aided by the burning of fossil fuels to generate heat. When air leakage is controlled, heat loss and energy used by the heating system are reduced. Poor degrees of ventilation and high levels of uncontrolled air leakage encourage mould growth and excessive moisture. This could potentially cause medical issues. A great option would be to build tight and ventilate right. Air leakage causes infiltration of moisture into the building envelope, leading to health issues and high repair costs.

When Is an Air Tightness Test Needed?

A building should ideally be air tightness tested early in the construction process and again at the end of the building project, although sometimes only the final check is carried out. The 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. 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.

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

With AF Acoustics, homes and businesses in Rayners-Lane have been getting quality air tightness testing. Our customers highly recommend us to other people due to the following benefits.

Helpful service and information

Our experience in serving diverse customers in Rayners-Lane is proof of our ability to satisfy your requirements no matter the size and type of building, or your circumstance. We have competent and accredited air testing professionals who provide a quality, convenient service. Our personnel will use their expertise to provide lasting solutions. Contact AF Acoustics in Rayners-Lane –the right team for your building.

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.

Picking a Time for Your Air Permeability Test

Our comprehensive air permeability testing in Rayners-Lane is available. Pick a time that is convenient for you in our responsive scheduling options. We won’t make you wait or make the process complicated.

Quick Turnaround on Test Certificates Where Possible

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

Competitive Pricing

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

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

We Conduct Tests for All Types of Buildings in Rayners-Lane

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. The best way to determine how much air seeps through a building’s fabric is through air permeability testing. 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. The design-stage SAP assessment or SBEM of a construction records its required air permeability rate. While the law requires the highest air permeability rate to be 10m3/h/m2, your building might have to get a lower rate to meet the carbon emissions target. 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.

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. Air permeability testing is a legal requirement for constructions in Rayners-Lane. This way, they can have high energy performance, meet building regulations requirements and get signed off by building control. Buildings where businesses are conducted will not cause discomfort to employees and clients because they have the legal air permeability rating. In addition, you get lower heating and cooling costs. A comfortable environment results in a higher productivity rate.

What Is 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. The air-tightness of a building is known as its ‘air permeability’ or leakage rate. Although not always seen, air leakage can occur through any gap, space or crack in a building’s fabric. Samples of houses in an area and all non-domestic buildings with more than an area of to m2 must be tested, according to Part L of the Building Regulations. The highest air permeability target set is 10m3/h/m2 but your building might need a much lower one. Air permeability is key in the following areas: i. A construction’s energy performance, ii. CO2 emission targets iii. Building Regulations Part L standards

What Is Part F Test?

We will help you with all your Parts L and 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. Building Control Body (BCB) has made a presentation of evidence of the test a compulsory aspect of a building’s sign-off process. 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

There are several levels of air leakage testing based on the kind, size and multifaceted aspects of a dwelling. Here they are: First Level – For building 1m3-4000m3, single and smaller non-dwellings, a single blower door fan is used to carry out the test. 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. 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

The measurement of air emitted by a building is tested to determine air permeability rating. The result is expressed as a quantity in the form of m3 per hour, per square metre of building fabric. Air tightness testing is required for new builds. A building has to achieve a lower rate to meet the carbon dioxide emission target. To get your building’s required air permeability rate, check its design-stage SAP assessment SBEM. An excessive amount of air leakage results in greater energy expenses, heat reduction and carbon dioxide emissions.

Air Tightness Testing of Commercial Buildings to Meet Approved Document L2A Requirements

Air pressure testing involves the calculation of air escaping through the openings in a building. The air leakage test result is written as m3/h/m2 – (m3 per hour) per square metre of building. Air leakage testing is a requirement of Approved Document L2A. The results of air permeability rate should not exceed 10m3/h/m2. The SAP or SBEM assessment for all buildings reduces the air permeability rate target. To get your building’s required air permeability rate, check its 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

We test the integrity of the smoke shaft to ensure the automatic opening ventilation is placed in the best condition. 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. With the right air permeability rate, the vents can operate at their best. We aim for the air permeability rate set by the vent manufacturers. Fans are placed in the smoke shaft to conduct an air tightness test. 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. Smoke shaft tests occur before installing and commissioning automatic opening ventilation.

Testing Extraction Fans for Air Flow

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 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. 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.

Air Tightness Test and Building Preparation Method

The measurement of air pressure in a building is known as an air tightness test. When air leakage is reduced in a building, the occupants will not experience discomfort and the energy performance will increase.

Holes and spaces in a building’s fabric might be hidden by the internal building finishes, making them hard to find. To ensure that the air tightness of a building is optimal, gaps and spaces in the building have to be found and measured.

At least 20% of different kinds of dwellings in a development have to be tested, according to new regulations; but the reliability of the sample from this type of testing is determined by the types of buildings in the development. We advise that all buildings undergo air pressure testing as there is a penalty for those that don’t.

What Should You Do Before Testing Your Building?

The client needs to send our test engineers the drawings of the development (plans and elevations) and target air permeability requirements. 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. To get the site ready, make the place air tight by closing and securing all external doors, windows, ventilation and smoke vents. Remember to turn off range cookers or stoves a day before testing as well as mechanical ventilation systems, and fill all drainage traps.

  • 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)

Building Envelope Measurement

We take the building envelope calculations before the test. A building envelope is the boundary between the conditioned and unconditioned environment of a building. The measurement is obtained from the construction drawings, and put in our calculations to conduct the test.

Air Permeability & The Envelope Area

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

Air Change Rate

The air change rate is important in designing a ventilation system, however, it is hardly a part of the actual design. The number of inhabitants and area of residence are used in measuring residential ventilation rates.

Cold Roof Envelope Area Measurement

Measuring if the roof area and ground floor area of a building are the same is vital. A cold roof has its insulation at the ceiling level, with 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. In the warm part of the insulation, is the barrier between the conditioned and unconditioned space.

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

Site Test Process

Check all weather conditions such as temperature, wind speed and barometric pressure. Connect a fan (or fans) to an aperture in the building envelope (e.g. door). Fix the instrument for testing. Record the air volume flow passing through the fan. Increase the speed of the fan slowly till it gets to 55-60Pa. At each fan speed, note the differences in air pressure in all the parts of the building.

Air Leakage Measurement

We analyse the recorded air tightness test data and present the results to the client in a technical report. In the event of test failure, we advise the client on appropriate mitigation measures. Our expert knowledge will help in highlighting the areas of air leakage. Testing for Air Permeability and Following Part L Building Regulations

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 energy costs and need for heating appliances due to a higher level of heat retention. 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. From the smallest to biggest building or development, we adhere to Building Regulations Part L and Building Standards. They also ensure that you spend less money. Here are the services we provide:

  • Air tightness test
  • Consultancy
  • Design reappraisal
  • Support services

Best Practice Procedures

The Building Regulations approved document Part L1A 2010 specifies that any new dwellings must be airtight. Less fuel and power are consumed by buildings. Part L1A further makes it obligatory for new buildings to be tested for air permeability in line with existing building standards.

Air Tightness Testing of Dwellings That Meet Technical Standard L1L1

Certain technical standards are to be employed during air pressure test in the UK, as specified by ATTMA, building regulations and other documents. The technical standards ensure that all companies have similar testing procedures. They are:

  • “Thermal Performance of Buildings. Determination of air permeability of buildings. Fan pressurisation method” BS EN 13829:2001, and
  • “Thermal performance of buildings – Determination of permeability of buildings – Fan pressurization method” ISO 9972:2015
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)

If you’re constructing a new dwelling, you have to comply with Approved Document L1A’s stipulation to test it. For development with two or more buildings, three units of each dwelling type or 50% of the dwelling type should be tested. Where there are only one or two new buildings, add an assumed value of 15m3/h/m2 to the DET/TER measurements; an air tightness test may not need to be carried out. To find if your building falls into this category, contact your SAP assessor. The required process for testing buildings for air tightness has been declared in ATTMA TSL1 for occupied buildings and ATTMA TSL2 for unoccupied ones. Non-Dwellings and residential buildings are required to test for air leakage. Non-dwellings with a typical floor area less than 500m2 may be exempt. Where testing is not carried out, an assessed air permeability of 15 m3/h/m2 must be used in calculations.

Part L Building Regulations Standards for England and Wales

An industry-wide competence scheme endorsed by the government is carried out by the ATTMA. It was launched in January 2015 as stipulated in the Technical Standard L1 and L2. 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 tightness testers can be divided into three categories

  • A single fan is the instrument used for the first level to examine single buildings and smaller non-dwellings from 1m3 to 4000m3.
  • 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.
  • Air tightness testing for phased, zonal handover, LCHR and multifaceted constructions is carried out by level three experts.

Air Pressure Test

Test reports are issued by registered and licensed air tightness companies who test buildings of different sizes and complexities. Extraction fans will be sealed temporarily; the results of the test are recorded in a short report. The organisation makes sure the report meets the company and government’s requirements.

Results of the Test

Our test and subsequent results are conducted and written to meet standard requirements, highlight any deviation from the standards and crosscheck air pressure values against target values. Our reports correctly note the client, air tightness tester, building and address. In the event that a building fails the test, we suggest methods of improving the building and what repairs to do on the building fabric if a retest is required.

Resources Air Tightness Checklist – Building

Please send your design air pressure figure to us and go through the list below before we arrive at your site.

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

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

Temporarily cover the following;

  • Trickle Vents: Close them.
  • MVHR Terminal/Extract Fans: Switch off and seal temporarily.
  • Air Bricks and Chimney Flues: Cover temporarily.
  • Cooker Hoods: Seal off from the inside or outside.

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 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.