Preston Air Tightness Testing, Licensed by AF-Acoustics

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. 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.

Changes to building regulations have addressed air leaks which affect a building’s 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. AF Acoustics, a licensed air tightness testing company, is available to provide testing services at your request. Our address is Preston. You can also call or email us for any of these services:

  • Assessments
  • Consultancy
  • 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. We are professionals who take the time to explain the testing process, we are able to give informed advice on where problem areas may occur during testing, and how improvements can be made based on results of air pressure testing. Our services provide great value for money at high 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

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. Air leakage and air pressure are also used in place of air tightness. Air leakage should not be confused with ventilation. Also called draughts or infiltration, air leakage is unrestrained movement of air through holes in a building fabric, while ventilation is the restrained and planned movement of air. Air leakage is uncontrolled ventilation. Air tightness testing is the approved method for gauging the entire air that has leaked through a building fabric. Too much air leakage leads to unnecessary heat loss and discomfort for the occupants. The government aims to lessen the quantity of air flowing from newly built buildings. Therefore, regulations have been put in place to reduce uncontrolled ventilation from the building envelope, sustaining the right temperature conditions without using so much fuel. Air tightness testing is a crucial activity that

  • shows the air leaking from gaps in a building.

Building plans will often consider air tightness at the beginning stages of development so as to measure up to stricter building standards. Incorporating this at the beginning of the construction process makes the development more cost effective and energy efficient.

Air Leakage

Air leakage is uncontrolled air movement in a building due to cracks. Air leakage is the uncontrolled movement of air into and out of a building through gaps and spaces in the building’s fabric. It is also referred to as infiltration and is the opposite of ventilation which involves well managed circulation of air in a building. 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. In England and Wales, air tightness testing has been obligatory since 2006. All new dwellings and non-dwellings over 500m² are to be tested for air permeability.

Effects of Air Leakage

When air escapes uncontrollably from a building, heat reduction occurs. Once the atmosphere is cold and windy, unwanted chilly air infiltrates the building through gaps, leading to heat reduction. It doesn’t stop there. Warm, damp air within the building escapes the gaps in its envelope. The water vapour in the moist air condenses on the inner wall surface holes. After a while, it is absorbed into building materials and diffuses, causing potential structural problems. Wooden sheathing or overlay becomes wet, making it weak.

The building becomes structurally damaged as time goes on.
Air leakage can also cause these problems:

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

The most effective method of lessening the damage caused by moisture is to control the flow of air into and out of the building. A properly installed air barrier minimises air leakage, which, in turn, minimises the potential for water vapour to condense on vulnerable wall structures. 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?

Climate change caused by carbon dioxide emission is an environmental hazard that government is trying to curb. Energy performance and air tightness is a key part of this plan. Fossil fuel is burnt to heat up a building. This leads to a discharge of carbon dioxide which increases global warming. The best way to reduce the quantity of fossil fuel burnt is by stopping air leakage which reduces heat loss. Poor degrees of ventilation and high levels of uncontrolled air leakage encourage mould growth and excessive moisture. This could potentially cause medical issues. Building tightly and ventilating the right way is highly recommended. Excess air leakage leads to moisture in the building envelope, causing large repair expenses and medical issues because of mould.

When Your Building Needs an Air Tightness Test

Best practice says that air tightness tests should be carried out early in construction and after the final phase. Newly completed constructions’ energy ratings can be influenced by the test results, as they are used in SAP and SBEM calculations. Large residential areas do not need each building to be tested. Instead, different types of dwellings are tested. Once every building in the residential development is not tested, the expected test result would have to be lowered by 2m3/h/m2. If 5m3/h/m2 was your target score, you must achieve 3m3/h/m2.

buildings that have not been tested are assessed for air permeability based on similar dwellings’ test scores +2m3/h/m2 at 50 Pa. It’s better to test each property because selective testing does not give a realistic picture of individual buildings. Besides, air permeability rates are difficult to achieve for untested buildings in such areas due to the +2m3/h/m2 penalty.

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

Numerous businesses and home owners have been aided by AF Acoustics air tightness testing proficient skills in Preston. We come highly recommended by our clients because of the following guarantees.

Helpful service and information

Having served many clients in Preston, we have the expertise to work on any type or size of building. We’ll work with you to carry out our tests and consultations at times that are convenient to you, delivering an exceptional quality, convenient service. Our knowledgeable and dependable air testing experts will provide lasting solutions to your problem. Call AF Acoustics for your air tightness testing.

Registered by the Leading Air Tightness Body in UK

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

Picking a Time for Your Air Permeability Test

We want you to be able to access comprehensive air tightness testing in Preston whenever you need it. We offer responsive scheduling options. You can schedule for air tightness testing at your convenience. 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.

Fair 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 Preston 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 Preston

We can test any building in Preston for air leakages irrespective of its size, complex nature or type. Our tests are conducted by highly qualified professionals and we issue ATTMA certificates. Air permeability testing calculates how much air moves through spaces in your building’s fabric. The result is expressed as a quantity in the form of The test results are described as m3/h/m2 – (m3 per hour) per square metre. of building fabric.

Air tightness testing is recommended by Approved Document L1A and L2A. Although your building is required to have a rating result of 10m3/h/m2, the actual result might have to be lower than that due to carbon emission requirements. You can find the required air permeability rate of your building in its design-stage SAP assessment or SBEM. 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 Preston, 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. Buildings where businesses are conducted will not cause discomfort to employees and clients because they have the legal air permeability rating. Heating and cooling expenses are also reduced and the environment is more productive.

A Description of Part L Test

In 2006, Approved Document L was reviewed and building regulations for air permeability became tighter. The air tightness test is presently a requirement for new buildings and reconstructions. Other names for air tightness are air permeability rate or leakage rate. Air leakage can occur through gaps, holes and cracks in the fabric of the building envelope (service penetrations, wall/roof junctions, etc), which are not always visible. 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 leakage is vital to a building’s energy efficiency and is needed to meet Building Regulations Part L and carbon emission standards.

A Description of Part F Test

We will ensure that you exceed all the Parts L and F standards. We deliver quality air permeability and extract fan flow rate testing, and also recommend skilled experts who will handle your water calculations, SAP calculations and Energy Performance Certificates.
Approved Document F of the Building Regulations demands that all mechanical extract fans in newly completed constructions undergo a flow rate test. Evidence of this test must be passed to the Building Control Body (BCB) as part of their sign-off procedure. There are 3 available methods for examining, recording and reporting the testing of extract fans. We use a vane anemometer, which is the third method called the minimum benchmark method, to conduct extract fan flow rate tests.


Types of Air Leakage Testing Services We Offer

There are different levels of air tightness testing established from the size and complexity of a building. An overview of each is provided 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. Air tightness testing for phased, zonal handover and LCHR constructions is done.

Approved Document L1 Air Pressure Testing of Houses

An air leakage test is a test to determine the level of uncontrolled air flow through gaps or cracks in the fabric of a building. The result is written as m3/h/m2 – (m3 per hour) per square metre of building envelope. Document L1A of Building Regulations declares air leakage testing to be mandatory. A lower air permeability rate might be needed due to carbon emission requirements. The required rate can be found in a building’s design-stage SAP assessment SBEM. Air leakage leads to heat loss, increased energy bills, greater CO2 emissions, and an uncomfortable atmosphere for inhabitants due to draughts.

Testing of Air Permeability of Commercial Dwellings, in Accordance with Document L2 Stipulations

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. Document L2A of Building Regulations declares air leakage testing to be mandatory. 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. The required air permeability rate for each building can be found on the design-stage SAP or SBEM report for that building. 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. Automatic opening vents help storey buildings dispel smoke when there is a fire. 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. To ensure that automatic opening ventilations work properly, their manufacturers have placed an air permeability target for them which we work towards. Fans are placed in the smoke shaft to conduct an air tightness test. The intended openings of the shaft (i.e. extract point and openings for ventilation grilles on each floor) are sealed off for the test so that the integrity of the shaft itself can be determined. The fixing and commissioning of the auto opening vents happen after the test is completed.

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 test fan 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. Another of such targets, as stated by Part F, is to have the standard intermittent extractor fans, like kitchen and bathroom extractors, in new constructions measured for air flow and results given to Building Control before the construction work is completed.

Air Tightness Test and Building Preparation Method

Air tightness test determines the level of air permeability in a building. The air tightness of a building improves its energy efficiency and internal environment.

Causes of excess air leakage are often hard to detect. These openings might not be seen because of the internal finishes that have been fixed. 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. 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 require the drawings (plans and elevations) and target 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. 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.

  • Turning off all range stoves and cookers (if applicable)
  • Turning off mechanical vents
  • Shutting all windows and external doors
  • Sealing ventilation grids and smoke vents
  • Filling the drainage stops

How We Measure the Building Envelope

We undertake building envelope measurements before getting to the dwelling for the test. The building envelope is the surface area of the structural barrier of a building. It separates the interior from the exterior part of the dwelling We use the building envelope measurements to get the right results when testing for air tightness.

Envelope Area Air Permeability

It is defined as air leakage rate per hour per square metre of envelope area at the test reference pressure differential of 50 pascals (50n/m2). The envelope area, or measured part of the building, is 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

Air change rates are often used as rules of thumb in ventilation design but they are seldom used as the actual basis of design or a calculation. The number of inhabitants and area of residence are used in measuring residential ventilation rates.

Evaluating a Cold Roof Envelope Area

It is important to make sure the roof area and ground floor area of a building are equal. 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.

Measuring a Warm Roof Construction’s Envelope Area

In a warm roof, an air barrier is inside the insulation which runs on the pitched roof rafters. The envelope area is the boundary between the internal environment and external environment (adjacent buildings), and can be found on the insulation’s warm part.

Getting the Building Ready

  • Temporarily seal and switch off all ventilation grids, smoke vents and mechanical ventilation systems
  • Close the windows and internal doors
  • Seal drainage traps.

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. Fix the instrument for 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.

Measuring air leakage

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. Air Leakage Testing and Compliance

The positive effects of an air tight building with efficient ventilation (natural, mechanical or a combination) cannot be underestimated. Here they are: Your heating expenses are less because heat doesn’t escape through a permeable building, and you won’t require appliances with more heating capability. 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. Infiltration of air is reduced and the inhabitants are more comfortable. Our air leakage tests are conducted according to building regulations and targets, whether we’re testing a small dwelling or big commercial development. We render cost-effective services that include air leakage tests, design reappraisal, consultancy and support services for dwellings and non-dwellings in Preston.


Good and Best Practice Standards

When constructing a new building, it should be built air tight, as stated by Building Regulations – Approved Document L1A. Reduced power usage and fuel conservation are important; that’s why the rule was put in place. Part L1A has demanded that all new dwellings be tested for air leaks in line with other regulations.

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

There are technical standards for air tightness test of buildings in the UK detailed by Air Tightness Test and Measurement Association (ATTMA). 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 for England and Wales, Part L 2010

If you are constructing a dwelling the Approved Document L1A states that you must perform an air pressure test. For developments of two or more dwellings, an air leakage test should be carried out on the three units of each dwelling type; or 50% of all instances of that dwelling type. A development with only two dwellings may not undergo a test if a suggested value of 15m3/h/m2 is stipulated in the DER/TER measurements. Your SAP assessor will be able to confirm if this is the case for your dwelling. ATTMA TSL1 and ATTMA TSL2 prescribe methods for testing occupied and unoccupied buildings. Air leakage testing is compulsory for residential areas and 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)

In January 2015, the ATTMA Scheme for Competent Air Tightness Testing Firms and Their Testers (The ATTMA Scheme) was launched. It is an industry competence scheme authorised by the government and specified in Technical Standard L1 & L2. Minimum Technical Competence (MTC) and National Occupation Standard (NOS) documents are the basis for the scheme.

Air leakage testers have three levels

  • Level 1: Testers can test dwellings and non-dwellings up to 4000m3 gross envelope volume when tested as a single entity, with a single fan.
  • Level Two: Testing for the air pressure is done in all single and multifaceted buildings. High rise (LCHR) buildings and phased handover/zonal buildings are excluded from this level, except a level 3 tester is in charge of the team.
  • Air tightness testing for phased, zonal handover, LCHR and multifaceted constructions is carried out by level three experts.

Air Leakage Test Report

Accredited testing companies issue air pressure reports. The testing companies seal extraction fans. After the test has been completed, they record test findings and results in a report. The report is in line with the company’s testing process set by government regulations and all relevant governing bodies.

Test Outcomes

AF Acoustics will make sure the result is written in line with test requirements, detect any part of the test that is not in line with the standards required and check actual air tightness against required rate. We will ensure the report correctly identifies the tester, customer, building and its address. If a building fails the test, we provide remedial suggestions before a retest is carried out.

Resources Air Tightness Checklist – Building

Before our test engineers arrive at the site, please adhere to what is written below and send the required air tightness target of your dwelling that is in the design to us.

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 <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.