Haywards-Heath Air Tightness Testing, Licensed by AF-Acoustics

Air tightness testing, otherwise called air pressure testing or air leakage testing, is the measurement of the outflow of air from a building’s fabric. It has been a mandatory part of the building regulations for new build and refurbishment projects since Approved Document L was revised in 2006.

Because air leakage is the process whereby air escapes through any crack or hole in the building envelope and influences its energy performance, building regulations have been modified to ensure a building has adequate air tightness. Our certificates are registered with the Air Tightness Testing and Measurement Association (ATTMA), an organisation that guarantees technical excellence in all air leakage measurement methods. We are a dedicated and approved air leakage testing service in Haywards-Heath and we can provide air permeability measurement whenever you require. You can also call or email us for any of these services:

  • Assessments
  • Consultancy
  • Part F mechanical extract fan flow rate testing.

We are registered members of the ATTMA. As a result, our air tightness certificates prove that the building requirements for your building have been met. We are professionals who take the time to explain the testing process, we are able to give informed advice on where problem areas may occur during testing, and how improvements can be made based on results of air pressure testing. Our customers get greater value for money spent, and our testing services are of superior quality.

Our Guarantee

  • Over 15 years experience
  • State of the art equiptment
  • Onsite Support
  • Next Day Report Turn Around
Call us today for a quote on 020 3372 4430
Or you can email us at info@af-acoustics.com

What is Air Tightness Testing?

Air tightness testing is a method of measuring the extent to which air is lost through leaks in the building fabric. 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 the recognised method used to measure total air lost through leaks in a building fabric. This is often referred to as uncontrolled ventilation (draughts). An excessive amount of uncontrolled air loss results in heat reduction, making the residents uncomfortable. Because the government is striving to scale back carbon dioxide discharge from new buildings, building rules now focuses on reducing air loss from the building envelope. This helps reduce CO2 emissions. Air tightness testing is vital in determining the energy efficiency of a new building, air leakage and the build quality. 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

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. 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 2006, air tightness of newly constructed buildings and non-dwellings with a floor area over 500m² became compulsory in England and Wales.

Air Leakage’s Resulting Outcomes

Air leakage leads to heat reduction. Heat loss is caused by influx of frosty outside air into a building through the openings in its envelope during draughts and cold weather, leading to an uncomfortable drop in temperature. It doesn’t stop there. Warm, damp air within the building escapes the gaps in its envelope. The warm air is filled with moisture, which hits the inner wall surface and condenses. Moisture is sucked into the building material, and this can lead to serious structural issues. Wet wooden framing or sheathing can rot and break down, diminishing its strength.

These problems will eventually cause structural harm to the building.
Other impacts include:

  • discomfort (cold homes)
  • increased heating bills (to counter the cold)
  • greater CO2 emissions (as result of additional heating required)

These effects can be mitigated by controlling the circulation of air into and out of the building. The potential of vulnerable wall structures to absorb condensed moisture is reduced when air barriers are properly installed and uncontrolled air flow is reduced. Passive or active ventilation is required to reduce water vapour, moisture odour and pollutants.


Why Should 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. Reducing air leakage reduces heat loss, which in turn reduces the amount of energy a heating system uses. Uncontrolled air leakage also results in health problems. Coupled with poor air circulation, it leads to the growth of mould and mildew. 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.

Recommended Period for 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 Pick AF Acoustics for Your Air Tightness Testing?

Business owners and home owners in Haywards-Heath have been helped by AF Acoustics air tightness testing. We come highly recommended by our clients because of the following guarantees.

Expert information and service

Our vast experience in serving a variety of clients in Haywards-Heath guarantees we have the expertise to satisfy your needs regardless your unique circumstances, type or size of property. Our accredited air testing experts are polite and competent. They are trained to provide the service you need and fit around your project. If you need knowledgeable and trustworthy air leakage experts who can provide exemplary results, AF Acoustics is the team you need in Haywards-Heath.

Registered member of the Air Tightness Testing & 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.

When Can You Call Us to Test Your Building?

You can access our complete air tightness test in Haywards-Heath at anytime. We have responsive scheduling options. Schedule for your air leakage testing at your comfort. We guarantee that there will be no delays or difficulties.

Next-day Turnaround on Test Certificate Where Possible

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

Affordable Prices

At AF Acoustics, we offer the most competitive prices in Haywards-Heath to ensure you have access to affordable air tightness testing when you need it. We keep the costs down, as we are a small business with low overheads. This allows us to be competitive with our pricing whilst guaranteeing a professional service.

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 Haywards-Heath

All domestic and commercial buildings in Haywards-Heath can be tested by AF Acoustics, no matter how complex they are. The air tightness tests are carried out by competent testers and you will be issued an ATTMA certificate. You can find out how much uncontrolled ventilation your building has by testing it for air leakages. The result of the air leakage test 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 a building envelope.

Approved Document L1A and L2A requires that buildings know their air permeability rates by taking the air leakage test. The maximum air permeability rate is 10m3/h/m2. The carbon discharge requirement for all buildings reduces the air permeability rate target. This target can be found in a building’s design-stage SAP assessment or SBEM. With air leakage comes heat loss, greater CO2 discharge, draughts, thermal bypassing and wind washing and poor energy performance. Warm air within a heated building rises and lowers the pressure at the building’s base to draw in air through the openings in the building fabric, leading to exfiltration or infiltration. Air tightness testing is required by law for domestic buildings to ensure energy efficiency and comfort within the home environment. It is also a legal requirement that all new builds have an air tightness test carried out to meet energy efficiency standards before it can get signed off by building control in Haywards-Heath. Buildings where businesses are conducted will not cause discomfort to employees and clients because they have the legal air permeability rating. It will also help you reduce the cost of maintaining heating or cooling in your commercial building, making it more productive.

A Description of 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. Air leaks through gaps and spaces in the building fabric such as service penetrations, walls and roof junctions. Sometimes, this is not obvious to occupants. It is compulsory for all commercial buildings with a gross area greater than 500m2 and a representative selection of domestic buildings to undergo air pressure test, as stipulated by 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 affects the building’s energy performance and is required to meet Building Regulations Part L and measure up to the standard for low carbon buildings.

Part F Test Explained

We will ensure that you exceed all the Parts L and F standards. First, we provide extract fan flow rate and air leakage testing. Then we put you in contact with competent professional to work on your Energy Performance Certificates, SAP and water calculations.
New buildings should ensure that all mechanical extract fans are tested for flow rate, as stipulated by Part F of the Building Regulations. Your building won’t be signed off until Building Control Body (BCB) has been presented the results of the test. There are 3 available methods for examining, recording and reporting the testing of extract fans. Using a vane anemometer, our testing procedure follows Method 3 – The minimum benchmark method.


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. Level 1: Air pressure testing for single dwellings and other smaller non-dwellings up to 4000 m³ gross envelope volume, typically tested with a single blower door fan. Level 2: Air pressure testing for simple and complex buildings larger than 4000 m³ gross envelope volume which does not include large and complex, high rise (LCHR) buildings, and phased handover/zonal buildings. Air tightness testing for phased, zonal handover and LCHR constructions is done.

Domestic Buildings Testing as Required by Approved Document L1

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 expressed as a quantity in the form of m3 per hour, per square metre of building fabric. Part L1A of Building Regulations stipulates that such tests be conducted. The carbon discharge requirement for all buildings reduces the air permeability rate target. The required rate can be found in a building’s design-stage SAP assessment SBEM. Excess air leakage causes heat loss and discomfort due to the influx of cold air, also causing increased energy bill expense.

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

Air pressure testing involves the calculation of air escaping through the openings in a building. The result of the air leakage test is expressed as a quantity of air leakage (m3 per hour) per square metre of building envelope. Air leakage testing is a requirement of Approved Document L2A. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. In order to comply with the SAP assessment, 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 or SBEM report for that building. Too much air leakage leads to heat loss (and consequently, higher CO2 emissions) and draught.

We Offer Smoke Shaft Air Pressure Testing

To ensure that the auto opening vent will perform optimally when fitted and commissioned, we test the smoke shaft to verify its air tightness. The automatic-opening vents are a key part of the fire strategy for multi-storey buildings to extract smoke in the case of a fire. For it to expel smoke from a building and keep the occupants safe during emergencies, the shaft must be air tight enough to create substantial pressure difference. 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. The shaft undergoes air leakage testing when fans are placed inside it. Then the openings are sealed off in all its parts so that the shaft can be thoroughly examined. This test is conducted before the automatic opening ventilation is fixed and commissioned.

Air Flow Measurement of Domestic Ventilation (extraction fan testing)

The mandate to construct well insulated and air tight buildings, has made it crucial for satisfactory, enhanced and balanced ventilation systems to be installed. We evaluate 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. Part F states that all new constructions must have intermittent extractor fans whose air flow rates will be calculated and the results given to Building Control before the building work is finished.

Specific Test and Building Preparation Procedure

An air tightness test measures the extent of air leakage in a building. When air leakage is reduced in a building, the occupants will not experience discomfort and the energy performance will increase.

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 most acceptable approach to show that a building fabric is impermeable is to identify leakage paths within it.

The new regulations stipulate that at least 20% of dwellings in a development be tested, but having a harmonious sample is dependent on the kind of buildings in the development. We advise that all buildings undergo air pressure testing as there is a penalty for those that don’t.

Pre-Test

Send the drawings of your dwelling (plans and elevations) and its target air permeability requirements to our test engineers. 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. In preparing the site to create an air-tight environment:

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

How We Measure the Building Envelope

We conduct building envelope calculations prior to the test. The building envelope is the physical separator between the indoors and outdoors. The measurement is obtained from the construction drawings, and put in our calculations to conduct the test.

Air Permeability of the 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

Although hardly used as a major deciding factor for calculation or design, air exchange rate is vital in ventilation design. Residential ventilation rates are calculated based on area of the residence and number of occupants.

Evaluating a Cold Roof Envelope Area

When evaluating the roof area of a building, it is important to ensure the area is the same as that of the ground floor. A cold roof has its insulation at the ceiling level, with space between the insulation and rafters.

Measuring a Warm Roof Construction’s Envelope Area

A warm roof is a roof system where the insulation is fixed along the rafters with an air barrier inside the insulation. The envelope area is the barrier between the conditioned space in the insulation and the unconditioned space outside.

Building Preparation

  • Turning off mechanical vents
  • Shutting all windows and internal doors
  • Temporarily seal vents and smoke vents
  • Filling the drainage stops

How the Test Is Done

Examine the wind speed, barometric pressure and temperature. Place the fan on an aperture within the building envelope. Set up the equipment for air tightness testing. Using the fan, measure the air flow volume, from the building fabric. Gradually increase the fan speed from 20-25 Pa to a maximum of 55-60Pa. Record how the air pressure differs at each fan speed.

Calculating Air Leakage

We analyse the air tightness test data, point out any air leakage path and send a report to clients. If the building fails the test, we suggest remedial measures to the client. Air 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. Better performing ventilation system Reduced chance of mould and rot, as moisture is less likely to become trapped You won’t experience much discomfort because there will be fewer draughts. From a single dwelling to the largest commercial development, we offer stress-free compliance measurements to Part L Building Regulations and Building Standards. We provide air tightness testing, consultancy, design reviews and support services on all buildings, both dwellings and non-dwellings in Haywards-Heath. We also provide cost-effective, local service that complies with all relevant Building Standards.


Good & Best Practice Methods

Building Regulation Part L1A 2010 stipulates that all new buildings must have low air permeability. The regulation helps to reduce the use of fuel and power. Part L1A has demanded that all new dwellings be tested for air leaks in line with other regulations.

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

Certain technical standards are to be employed during air pressure test in the UK, as specified by ATTMA, building regulations and other documents. 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

Part L 2010 Building Regulation Standards for England and Wales

Approved document L1A has made it compulsory for all new buildings to be tested for air leaks. For development with two or more buildings, three units of each dwelling type or 50% of the dwelling type should be tested. If the development has one or two dwellings only, an air tightness test might not be taken if the DET/TER calculations assume a value of 15m3/h/m2. Your SAP assessor will be able to confirm if this is the case for your dwelling. There are different ways that Dwellings and Non-Dwellings should be tested. ATTMA TSL1 and ATTMA TSL2 have clearly stated these. Air leakage testing is required on all residential developments (this may be a sample of units) and certain Non-Dwellings. Buildings with a floor area of less than 500 m2 might not have to take the test. Where air tightness testing is not done, an assumed air permeability rate of 15 m3/h/m2 is used.

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. 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 leakage testers have three levels

  • Air tightness testing for single buildings and smaller non-dwellings not more than 4000m3 is done with a fan.
  • The second level examines simple and complex buildings greater than 4000m3, with the exclusion of large zonal buildings and complex high-rise buildings unless a level three tester is in charge of the procedure.
  • Air tightness testing for phased, zonal handover, LCHR and multifaceted constructions is carried out by level three experts.

Report on Test for Air Permeability

Air leakage test reports are given by authorised organisations that test different buildings. Temporary sealing of extraction units will be done by the tester; all test results will be noted, and a shortened form report will be written which will include the findings of the test. The report adheres to the company’s methods and all standards and requirements of Building Regulations.

Test Results

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. Clients’ test reports contain their names, construction, address; the tester’s name is also included. Where it’s needed, we will identify if your building passed or failed the test and suggest ways to repair the building envelope before a retest is done.

Resources Air Tightness Checklist – Building

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

Air Leakage Pathway List –Ensure you thoroughly check the following equipment. Fill up drainage traps. Here are the pieces of equipment to cover, fill or seal:

  • Extract fans
  • Hoods of cookers
  • Drainage traps
  • Metre boxes
  • Boilers
  • Radiators, fans and heaters
  • Hot water tank
  • Chimney
  • Air bricks
  • Skirting and coving
  • Bath panel
  • Tumble drier extracts
  • MVHR
  • Soil panel

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.