ATTMA Licensed Air Tightness Testing in Harringay

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

Revisions were made to building regulations to address air leakages – a process where air escapes through any opening in the building, affecting its energy efficiency. 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. AF Acoustics, a licensed air tightness testing company, is available to provide testing services at your request. Our address is Harringay. You can also contact us for assessments and consultancy services. In addition to air leakage testing, we provide Part F Mechanical extract fan flow rate testing.

Because we are ATTMA members, any air tightness certificate we issue shows that the construction has met building regulation standards. 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 goal is always value for money and customer satisfaction. We are professionals and our services are of the highest quality.

Our Guarantee

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

Air Tightness Testing – What Does It Mean?

When a building is assessed during an air tightness test; the internal thermal envelope of the building is examined for leakages and the quantity of air passing through it. Other names for air tightness testing are air leakage testing and air pressure testing. Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric (often referred to as infiltration or draughts) and not ventilation, which is the controlled flow of air in and out of the building. Air tightness testing is done to calculate the total quantity of air that escapes through cracks in the building. Such air leakage is called uncontrolled ventilation (draughts). Once too much air escapes, heat reduction occurs, causing the temperature of the building to drop to a level that isn’t comfortable for those residing in it. As Government strives to reduce CO2 emissions from new buildings, building regulations now place greater emphasis on reducing air leakage from the building envelope. This reduces fuel consumption and CO2 emissions. Air tightness testing is important in establishing air leakage from a building’s fabric, the energy efficiency of a new building and in identifying poor build quality within new developments. 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.

What Is 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. Also called infiltration, it differs from ventilation which is the regular, planned and restrained flow of air into a building. As air leakage is uncontrolled, too much air may enter the house during cold or windy weather, leading to excessive heat loss and uncomfortable cold draughts. 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. Air tightness testing is compulsory for all new constructions and non dwellings with a floor area over 500m² in England and Wales. This came into effect in 2006.

Air Leakage’s Resulting Outcomes

Air leakage causes heat loss. 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. Once there’s infiltration, exfiltration will occur in another part of the building. Warm, moist air seeps into cool cavities in the building’s fabric. When moist air hits a cooler surface within a wall structure, water vapour in the air can condense and collect inside these spaces. Moisture can then be absorbed in building materials and cause serious defects. Wet wooden overlay or framing can decay, decreasing its durability.

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. Adequately installed air barriers minimise air leaks and the probability of vapour condensing and diffusing into the building’s structure. To get rid of pollutants, water vapour and moisture odour, the building must be well ventilated.


Why is an Air Tightness Test Important?

Air tightness is a key factor in building energy efficiency, and is a part of government-led initiative to combat climate change through improvements in building energy performance. Heating buildings contribute to global warming and CO2 emissions, since fossil fuels are used to create heat. The best way to reduce the quantity of fossil fuel burnt is by stopping air leakage which reduces heat loss. Uncontrolled air leakage also results in health problems. Coupled with poor air circulation, it leads to the growth of mould and mildew. The best advice is to “Construct tightly, ventilate properly”. Excess air leakage leads to moisture in the building envelope, causing large repair expenses and medical issues because of mould.

When Should an Air Tightness Test Be Done?

It is best practice to complete an air tightness test early on and then again at the final stage. The test results are used in SAP and SBEM calculations, this impacts the energy rating of new building. Individual property is not tested in a large residential development. The test is done on different types of houses within the area. 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.

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. Because selective testing does not conduct tests for all buildings, a tested building might have a much higher air tight rate than an untested building; making it unreliable. The 2m3/h/m2 penalty added to untested buildings makes the air permeability rate hard to achieve.

Why Pick AF Acoustics for Your Air Tightness Testing?

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

Service and knowledge

Our vast experience in serving a variety of clients in Harringay guarantees we have the expertise to satisfy your needs regardless your unique circumstances, type or size of property. 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. If you need knowledgeable and trustworthy air leakage experts who can provide exemplary results, AF Acoustics is the team you need in Harringay.

Air Tightness Testing and Measurement Association (ATTMA) Registered

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

We want you to be able to access comprehensive air tightness testing in Harringay whenever you need it. Simply fix a convenient time for your building’s air permeability test. We offer responsive scheduling. We guarantee no delays or complications regarding scheduling.

Next-day Turnaround for Certificates

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

Competitive 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 Harringay 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 Harringay

Regardless of the size, type, or complexity of your domestic or commercial building in Harringay, we can provide you with air tightness testing, carried out by an experienced and professional air tightness tester and issue you a certified ATTMA certificate. Air permeability testing calculates how much air moves through spaces in your building’s fabric. The results are registered as The test results are described as m3/h/m2 – (m3 per hour) per square metre of building.

Air leakage testing is required by Approved Document L1A and L2A. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. In order to comply with the carbon emission target, it may be necessary to achieve a lower air permeability rate. The required air permeability rate for each building can be found on the design-stage SAP assessment or SBEM for that building. Excessive air leakage causes discomfort due to heat reduction and carbon dioxide discharge. It also creates convective loops within a building’s internal structure, leading to energy loss. 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. In Harringay, 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. With air leakage tests, business areas are more comfortable for employees and customers. In addition, you get lower heating and cooling costs. A comfortable environment results in a higher productivity rate.

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. The air-tightness of a building is known as its ‘air permeability’ or leakage 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. Part L of the Building Regulations requires that all non-domestic buildings which have a gross floor area greater than 500m2, be subject to mandatory air permeability tests. For domestic dwellings, a sample of houses (in a development) must be tested. 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

A Description of Part F Test

All your Part L and Part F testing requirements can be met by us. In addition to conducting your air pressure test and extract fan flow rate testing, we can put you in contact with professionals who provide SAP calculations, Energy Performance Certificates, and water calculations.
New buildings should ensure that all mechanical extract fans are tested for flow rate, as stipulated by Part F of the Building Regulations. Evidence of this test must be passed to the Building Control Body (BCB) as part of their sign-off procedure. Extractor fans can be tested and recorded, and test reports submitted using 3 methods. AF Acoustics employs the minimum benchmark procedure (method 3), which involves using a vane anemometer.


What Kinds of Air Tightness Testing Services Do We Offer?

The size, type and multifaceted parts of a building determine the level of air pressure testing it will receive. There are 3 levels and they are listed below. A single blower door fan is the instrument used for the first level to examine single buildings and smaller non-dwellings from 1m3 to 4000m3. 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 Three: At this level, tests for the air pressure of high rise (LCHR) buildings and phased handover/zonal buildings.

Air Tightness Testing of Houses and Flats to Meet Approved Document L1

Air pressure testing, involves the calculation of air escaping through openings in a building. The result is written as m3 per hour per square metre of building. Air pressure testing is compulsory, according to Approved Document L1A. In order to comply with the carbon emission target, it is necessary to achieve a lower air permeability rate. The design-stage SAP assessment SBEM of a construction records its required air permeability rate. Uncontrolled ventilation can cause several problems. They are: infiltration of cold air, reduction in heat, more CO2 emission and higher energy costs.

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

Air tightness testing determines the extent of air leaking from a building’s envelope. The result is expressed as a quantity in the form of air pressure (m3 per hour) per square metre of building fabric. Air leakage testing is a requirement of Approved Document L2A. The maximum air permeability rate for a dwelling tested is 10m3/h/m2. Your building may need a lower air permeability rate to meet the SAP or SBEM assessment. To get your building’s required air permeability rate, check its design-stage SAP or SBEM assessment. Uncontrolled air leakage can cause several problems. They are: infiltration of cold air, discomfort, reduction in heat, and higher CO2 emission rate.

Air Permeability Testing of Smoke Shafts (for automatic opening vents)

We test the integrity of the smoke shaft to ensure the automatic opening ventilation is placed in the best condition. Automatic opening vents are crucial during fire emergencies in storey buildings, as they clear out smoke from the buildings. For the vents and fans to operate at the expected level, the smoke shaft must be air tight to create a difference in air pressure and give emergency services when needed. We’re committed to automatic opening vents builders’ target for air permeability. This enables the vents to work efficiently. An air pressure test is taken for the smoke shaft by installing a fan inside. 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 test takes place in advance of the automatic-opening ventilation equipment being installed and commissioned.

Measurement of Air Flow of Domestic Ventilation

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 are able to test extraction rates. It is important to ensure the ventilation strategy is working effectively. This helps to remove pollutants from the air and control excess humidity, particularly in rooms such as bathrooms and kitchens. 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.

Air Tightness Test and Building Preparation Method

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

It is difficult to notice unwanted openings in a building envelope. They might be blocked by the internal finishes. If you know the leakage paths of a building, you will know if it is air tight.

Under the new regulations developers must test 20% of the dwellings on a site but this also depends on the amount of differing house types to ensure that a consistent sample is taken throughout the construction of the development. We recommend that all dwellings be tested, as there is a penalty for developments that are not tested.

Pre-Test

Clients should send the drawings (plans and elevations) and air permeability requirements to our engineers. This is to have the needed information for the building and to know the size of the building envelope before coming to the site. Air tightness testing lasts for 30 to 60 minutes and wind speed is not more than 6m/s. Making your building ready by ensuring it has an air tight environment will involve:

  • Seal and turn off all ventilation, smoke vents and mechanical ventilation systems
  • Close the windows and open internal doors
  • Fill drainage traps
  • Switch off range stoves/cookers 24 hours before the test

How We Measure the Building Envelope

We conduct building envelope calculations prior to the test. The building envelope, is the physical barrier between the exterior and interior of a construction. The calculations, which are extracted from the drawings, are fed into our estimations when testing your building for air leaks.

Air Barrier Envelope Area

Air permeability is calculated at air leakage rate per square metre of envelope area. In relation to air permeability, the air envelope area is the total area of the measured part of the building without subtracting from the area of the junction of internal walls, or floors and ceilings. The envelope area of a terraced house includes the party walls while that of a flat in a multi-storey building includes shared ceilings, walls and floors.

Air Changes Per Hour

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

Calculating the Envelope Area of a Cold Roof

The area of the roof and ground floor should be the same. A cold roof is a roof that has its insulation in the ceiling and there’s a huge space between the insulation and rafters.

Measuring a Warm Roof Construction’s Envelope Area

A warm roof has the insulation running along the pitched roof rafters with an air barrier normally running parallel along the inside face of the insulation. In the warm part of the insulation, is the barrier between the conditioned and unconditioned space.

Building Preparation

  • Open and secure all internal doors;
  • Close all windows;
  • Switch off all mechanical ventilation systems;
  • Seal vents;
  • Close smoke vents;
  • Fill all drainage traps; check weather conditions (wind speed, temperature, barometric pressure);

Building Test Method

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). Set up testing equipment. Using the fan, measure the air flow volume, from the building fabric. Slowly raise the fan speed from 20-25Pa to 55-60Pa. Note the difference in air pressure in several parts of the building at each fan speed.

Evaluating Air Leakage

We can determine where air leakage is occurring through our test procedure. Once the test has been completed, we crosscheck the data and send a report to you. If the test fails, we will advise you about corrective measures. Testing for Air Tightness & Meeting Part L Standards

Making sure your building is air tight and has adequate ventilation, be it natural, mechanical, or a combination of the two, will aid your comfort. Find below the benefits: Your heating expenses are less because heat doesn’t escape through a permeable building, and you won’t require appliances with more heating capability. The ventilation system will operate optimally Less mould will be trapped in the building fabric as a result of less moisture. Fewer draughts, causing more comfort Be assured that you’ll get a test that meets all the regulations and standards no matter how big or small your building is. They also ensure that you spend less money. Here are the services we provide:

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

Best Practice Processes

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 states that any new building must undergo an air pressure test, according to present regulations.

Testing for Air Tightness in Building Fabrics of Dwellings to Adhere to Technical Standards L1

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

Part L 2010 Building Regulation Standards for England and Wales

If you’re constructing a new dwelling, you have to comply with Approved Document L1A’s stipulation to test it. Where there are two or more new buildings in an area, conduct a test on 50% of all examples of a kind of dwelling or 3 units of a dwelling kind. For developments where no more than two dwellings are constructed, it may be possible to avoid the need for any pressure testing by using an assumed value of 15m3/h/m2 within the DER/TER calculations. Your SAP assessor will let you know if you can do this for your building. ATTMA TSL1 and ATTMA TSL2 prescribe methods for testing occupied and unoccupied buildings. Air tightness tests are to be carried out on all residential developments (all the buildings or a selected group) and all certain Non-Dwellings. If your building has added an estimated assessed rate of 15 m3/h/m2 in its calculations or its useful floor space is less than 500 m2, it may not have to take the test.

Building Regulations for England and Wales, Part L

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. The scheme echoes the conditions of the Minimum Technical Competence (MTC) and the National Occupation Standard (NOS) documents.

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.
  • Air tightness testing is done in all dwellings but big phased handover/zonal and high rise (LCHR) constructions are not included except a level three tester is the head of the team.
  • Level 3: These are air tightness experts who can cover large, complex and or high-rise buildings and or phased handover or zonal compartmentalisation.

Air Leakage Test Report

Test reports are issued by registered and licensed air tightness companies who test buildings of different sizes and complexities. The testing companies seal extraction fans. After the test has been completed, they record test findings and results in a report. This is done according to the testing organisation’s procedures and Building Regulation standards.

Air Tightness Test Results

AF Acoustics will ensure the test result is written in accordance with the test standard requirements, identify any deviations from the relevant standards within the report and check air tightness against target value. We will ensure the report correctly identifies the tester, customer, building and its address. Where applicable, we will identify pass or failure of your building and provide recommendations for any remedial action or improvement to the building if any further testing is required.

Resources Air Tightness Checklist – Building

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

Air Permeability Pathway Checklist – Use this checklist to make sure you are ready for the test. Ask yourself, “Have I sealed any visible opening?” Check the following appliances.

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

Here are the appliances you should seal temporarily;

  • Cooker hoods
  • Extractor fans/MVHR terminals
  • Trickle vents
  • Chimney flues and air bricks

Air Tightness Testing FAQ’s

Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric of a building (sometimes called infiltration or draughts).

This is not to be confused with ventilation. Which is the controlled flow of air into and out of the building through purpose-built ventilators that are required for the comfort and safety of occupants.

Too much air leakage leads to unnecessary heat loss and discomfort to the occupants from cold draughts.

At AF Acoustics, we will endeavour to help you identify air leakage/infiltration paths.

There are a number of methods we employ to do this, including:

  • Smoke pens– smoke can be used to identify where air is moving when the building is being tested
  • Depressurise the building –By depressurising the building air is drawn in and can be felt at the air leakage points, our experience will be able to pin point these locations easily, whist the building is being depressurised, we will be able to show you around and will point you to the areas that have air leakage. You will usually be able to feel the air blowing on your skin when you are close to leakage areas, using the smoke pens these leakage points can be seen as the smoke changes from a steady flow to a turbulent flow.
  • Smoke testing – if the air paths are less direct it may be necessary to use smoke puffers and/or fill the building with smoke and pressurise/depressurise again. Points of air ingress and egress should be identifiable.
  • Thermography – if it is still not apparent where air is escaping, infra-red cameras can be used to identify hot spots and cold spots on the internal and external surfaces of the building. This requires a temperature difference between the inside and outside.

In the vast majority of cases the first two methods are sufficient to identify the most significant air leakage paths along with our expertise we will be able to point our the problem areas should they arise. The air leakage areas will have to permanently sealed and the test repeated to reduce the air permeability of the building. Where problems are larger and sealing cannot be addressed on the day, the building may need to be re-tested at a later date.

A test certificate from The Air Tightness Testing and Measurement Association (ATTMA)

A testing procedure is to be carried out to comply with TSL1 for domestic or TSL2 for commercial. The test certificate will include sufficient information to describe the building tested e.g. location, type and size (the envelope area is an important component in calculating the air permeability and must be accurate) plus the design air permeability as well as the actual result. A testing procedure should be representative of the actual building performance.

An indicative result is available at the time of testing. Certificates can be issued within a day of testing.

If required, you can request all calculations including pre, and post environmental measurements, individual static pressures, envelope area breakdown, flow readings and calibration certificates at no extra charge.

Air permeability is essentially a function of the pressure difference between the inside and outside of the building and the air flow rate through the fan(s), necessary to produce a pressure difference. This is averaged out over the envelope area. The result takes account of environmental conditions.

The final air permeability at 50 Pa is based on a logarithmic graph of pressure difference and flow rate, the graph should:

  • Have at least 7 points (ideally 10 or more).
  • At least one building pressure >50Pa and at least on <50Pa, No building pressures >100Pa.
  • The lowest figure should be at least 10 Pa or 5 times the ‘static pressure’ (the pressure difference between inside and outside without the fans)
  • The readings should be no more than 10 Pa apart.
  • The correlation coefficient r2 >0.98
  • The gradient of the graph (n) should be between 0.5 and 1.0.

These are aspects that the building control should check carefully if choosing to accept air permeability results from non-accredited testing bodies.

Most air tightness tests for domestic units and simple commercial units are carried out in 45 – 60 minutes. This time may be extended if the test fails and leakage paths are investigated. We will normally charge for a retest depending on how much work is to be carried out.

On larger commercial units, which require 1 large air test fan, air tests take 1 hour if all temporary sealing has been completed prior to starting the air test.

If complicated or very large buildings are being air tested with multiple fan units, allow up to 4 hours for the test and longer if investigations are required.

The envelope area is calculated from the drawings and verified on site. The envelope of the building is all the surfaces that separate the heated interior from the unheated exterior of the dwelling. This includes walls, floors and the roof.

Generally, this involves mounting a door profile and incorporating one or more electrical fans into an external door opening(s). Depending on their orientation, the fans can be used to pressurise or depressurise the building. The resulting difference between the external and internal pressure can be used to calculate the permeability of the building envelope (given that the envelope area is known).

This permeability is an indicator of how air tight the building is, and whether there are openings in the envelope. Generally, 10 differential pressure points are taken at different fan flows to establish an accurate result for the building. Our certified specialised software is used to establish an accurate Air Tightness Test result.

Our experts at AF Acoustics will provide a simple checklist for building preparation, which includes the following:

  • The building should be ‘completed’
  • All external doors and windows closed
  • All internal doors wedged open
  • All fire dampers, ventilation louvres and trickle vents closed but not sealed
  • Mechanical ventilation turned off with inlet/outlet grilles sealed
  • All combustion appliances switched off
  • Drainage traps must contain water
  • Any ‘Aga’ type stoves must be switched off for a minimum of 24 hours prior to testing

All building preparations should be made before our test engineers arrive on the site this will ensure a smooth testing process and increase your dwelling’s chances of passing the test the first time. We will seal all the vents ourselves.

For multiple dwellings it may also be necessary to agree on the test programme with the building inspector before arriving on site.

Where possible, it is helpful to accurately calculate the envelope area and confirm the fan installation arrangements based on architectural drawings before coming to the site.

  1. How many plots are going to be tested
  2. The location
  3. The plans and elevation drawings, cross sections if possible
  4. The air permeability target
  5. A brief description of the property; e.g. does it have fireplace or a loft?

For dwellings, sufficient information is required to identify the different dwelling types and the number of each such as General Arrangement/Site Plan and Schedule (including other important details such as variation in storey height or construction method).

For buildings other than dwellings, the approximate envelope area is the key factor for quoting. It is required to establish the necessary fan arrangement. This affects the time on site and potentially the number of people, and this can be calculated from drawings – floor plans and elevations.

The testing body may also need to identify the potential aperture(s) into which test equipment is to be installed. In some circumstances this may require additional time on site, extra people or customised templates.

Approved Document L states that Building Control can accept evidence from BINDT or ATTMA Registered testers. However, the BINDT scheme was closed down at the end of 2014, subsequent to the last revision of Approved Document L. Additionally, The Independent Air Tightness Testing Scheme (iATS) is an authorised Competent Persons Scheme created for companies (including sole traders and partnerships) that carry out Air Tightness Testing.

The common leakage sites are:

All pipe works within the kitchen and bathrooms

  • Holes in the walls
  • Radiator pipe work penetrations in floors and walls
  • Sanitary pipes penetrating walls and floors
  • Junction between floor and wall under kitchens and baths
  • Junction lower floor / vertical wall
  • Junction window sill / vertical wall
  • Junction window lintel / vertical wall
  • Junction window reveal / vertical wall (horizontal view)
  • Vertical wall (cross section)
  • Perforation vertical wall
  • Junction top floor / vertical wall
  • Penetration of top floor
  • Junction French window / vertical wall
  • Junction inclined roof / vertical wall
  • Penetration inclined roof
  • Junction inclined roof / roof ridge
  • Junction inclined roof / window
  • Junction rolling blind / vertical wall
  • Junction intermediate floor / vertical wall
  • Junction exterior door lintel / vertical wall
  • Junction exterior door sill / sill
  • Penetration lower floor / crawlspace or basement
  • Junction service shaft / access door
  • Junction internal wall / intermediate floor

Our team of experts can support you through the following

  • Tender Stage – Estimate pricing structures and general advice
  • Design Stage – Desktop or site-based design team meetings
  • During Construction – Ongoing audits of the building, Building Control liaison, sample testing of completed areas of ‘comfort testing’ prior to final testing
  • Upon completion – preparation advice, shortly prior to the air testing, final testing and leakage diagnosis

Additional AF Acoustics services – including noise survey, sound insulation testing services noise impact assessments

Employing the services of a reputable and accredited air tightness testing consultant, such as AF Acoustics, can help identify and remedy potential problem details in a building design prior to and during construction.

The Air Tightness Testing and Measurement Association (ATTMA) is approved by Department for Communities and Local Governments (DCLG) and is listed in the Building Regulations as an authorised Competent Persons Scheme for air tightness testing.

As an ATTMA registered company, AF Acoustics is independently certified by ATTMA with a scope covering air tightness testing to the ATTMA Technical Standards (TSL1 & TSL2) and BS EN: 13829 (2001), demonstrating knowledge and understanding, which enables us to test both commercial and domestic developments in accordance with relevant building regulations.

Part L sets the energy efficiency standards required by the Building Regulations. It controls:

  • The insulation values of building elements
  • The allowable area of windows, doors and other openings
  • Air permeability of the building
  • The heating efficiency of boilers
  • The insulation and controls for heating appliances and systems together with hot water storage and lighting efficiency

It also sets out the requirements for SAP (Standard Assessment Procedure) Calculations and Carbon Emission Targets for dwellings. In addition to insulation requirements and limitations of openings of the building fabric.
Part L also considers:

  • Solar heating and heat gains to buildings
  • Heating, mechanical ventilation and air conditioning systems
  • Lighting efficiency
  • Space heating controls
  • Air permeability
  • Solar emission
  • The certification, testing and commissioning of heating and ventilation systems
  • Requirements for energy metres

Building Regulations are administered separately in England, Scotland and Wales.

The objective is to measure the volume of conditioned air escaping through the building envelope via uncontrolled ventilation at an induced pressure difference of 50 Pa. A simplified process is shown below:

  • Check site preparation / Prepare site – including temporary sealing.
  • Calculate the envelope area.
  • Take environmental condition measurements – wind speed, temperatures, barometric pressures.
  • Install door frame canvas for the fan into a suitable aperture(s), usually the front door.
  • Install fan(s) into frame canvas
  • Connect monitoring equipment.
  • Check the static pressure.
  • Take multiple pressure difference readings and record fan flow rate(s) – allowing sufficient time for the pressure readings to stabilise.
  • Check the static pressure.
  • Process the readings through appropriate software – check that readings fulfil the requirements of the standard.
  • If the building fails, attempt to identify/quantify air leakage/infiltration paths.
  • Disconnect measurement equipment.
  • Remove the fan(s).
  • Remove the door frame canvas.

No. However due to the penalties occurred to the air permeability value of non-tested properties, every property is usually tested. We can test all dwellings, including domestic buildings, industrial units, warehouses, schools, hospitals, residential care homes, hotels, offices, and retail units.

All new buildings and dwellings should be tested, but there are some exceptions and they are explained below:

  • ‘Small’ commercial buildings (with a floor area less than 500m2) may avoid the need to test by accepting an assumed poor value for air permeability (15m³/(h.m²) at 50 Pa) but this may add costs to other aspects of the building specification so that the building meets the overall target for emissions.

No. Air tightness testing applies to:

  • All new dwellings (based on a sampling rate)
  • All new buildings other than dwellings
  • Extensions to existing buildings that create new dwellings

Air tightness is an important factor in assessing the overall carbon emission of a building via the appropriate calculation methodology:

When a building is air tight, the amount of fuel needed to heat it is reduced. This conserves fuel and reduces the carbon dioxide produced, thereby lowering carbon emission and energy bills.

If you are building a new domestic property or commercial property of a certain size, it will need to undergo air tightness testing. This assesses the building for ‘air permeability’, checking for air leakage through gaps, holes and other areas. The Government has SAP (Standard Assessment Procedures) in place for air tightness testing, setting standards buildings must comply with to be energy efficient.

All residential properties and non-dwellings properties over a certain size (with a floor area greater than 500 m2) must undergo air tightness testing. With larger developments, a sample number of the buildings must be tested, depending on the size and construction of the properties. However, in practice all dwellings are likely to be tested, as non-testing attracts a severe penalty.

In a property where air tightness is below the recommended standard, the following problems can occur:

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

AF Acoustics lead air tightness testing Specialist, Gerard is your first port of call for all air tightness questions enquiries and surveys.