Air Tightness Testing, Certified by AF-Acoustics, in Sandhurst

Air tightness testing, also called air leakage testing or air pressure testing, calculates the quantity of air escaping through openings in a building. It has been a mandatory part of the building regulations for new build and refurbishment projects since Approved Document L was revised in 2006.

Changes to building regulations have addressed air leaks which affect a building’s energy efficiency. Our certificates for air tightness testing are registered with the Air Tightness Testing and Measurement Association (ATTMA), a professional body that focuses on high quality air tightness testing and air permeability applications. We are a dedicated and approved air leakage testing service in Sandhurst 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.

As registered members of the Air Tightness Testing and Measurement Association, our air leakage test certificate is accepted as evidence for Building Regulations sign-off. We don’t just provide air tightness testing. We describe the process thoroughly, give expert advice on areas that could be problematic during testing, and suggest improvements based on the air permeability rating of the building. Our customers get greater value for money spent, and our testing services are of superior quality.

Our Guarantee

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

What is the Assessment of a Building’s Air Tightness?

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. It can also be called air pressure testing or air leakage testing. While the normal restrained movement of air all through a building is called ventilation, the unchecked movement of air through cracks and gaps in a building is air leakage; also known as draught or infiltration. Draughts are uncontrolled ventilation. Using air tightness testing, the total air lost can be estimated. An excessive amount of uncontrolled air loss results in heat reduction, making the residents uncomfortable. Regulations now concentrate on minimising air leakage from the building envelope thereby reducing the amount of fuel burned for maintenance. This helps reduce carbon dioxide 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 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. This can make a building more energy efficient since air leakage is under control. It will also be cost effective and of high quality.

What Air Leakage Is

Air leakage occurs when air escapes through holes and gaps in a building. 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. Air leakage testing plays a significant role in the energy-saving efficacy of properties. With air tightness testing, you can be sure that the building has met the stipulated targets used for energy calculation and air tightness. 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.

What Are the Problems Air Leakage Can Cause?

Air leakage leads to heat reduction. Once the atmosphere is cold and windy, unwanted chilly air infiltrates the building through gaps, leading to heat reduction. As cold seeps inside, warm moist air escapes through the cracks and gaps in the building. Some of it settles within the building’s fabric. 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. The strength of the outer wooden covering is drastically reduced because it is wet.

Over time, any of these conditions can cause structural damage.
Other effects of air leakage are:

  • Discomfort; the environment is colder
  • Higher heat cost; a way of combating the cold, and
  • More CO2 emission because of the extra heat used.

The best way to reduce the harmful effect of moisture is to efficiently control how air moves 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. Proper ventilation, whether active or passive, is critical in expelling undesirable damp scents, water vapour and polluting substances.


Why You Should Conduct an Air Tightness Test

Air tightness is an important factor in a building’s energy efficiency and is part of government’s plan to battle environmental change by regulating the energy performance of buildings. Heating buildings involves burning fossil fuel which increases CO2 emissions and causes global warming. A reduction in air leakage lessens the heat needed to keep a building warm. 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. High levels of air leakage can lead to moisture ingress into the building fabric, resulting in expensive repair costs and potential health problems due to mould.

When Should an Air Tightness Test Be Done?

Best practice dictates that you complete an air tightness test early in the build process, and then again after the construction process is completed; although not all builds have the first test phase. The test results are part of SBEM and SAP calculations, therefore they influence the total energy ratings of new buildings. Larger residential developments do not require testing to be completed on each individual property, instead, testing is undertaken on the different dwelling types within the development. With selective testing, you get a penalty of +2m3/h/m2. Houses that have a target score of 5m3/h/m2 must get a lower score of 3.

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

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

Numerous businesses and home owners have been aided by AF Acoustics air tightness testing proficient skills in Sandhurst. We are recommended by our clients for the following reasons.

Helpful service and expert knowledge

Having served many clients in Sandhurst, we have the expertise to work on any type or size of building. Our qualified air tightness testing professionals will work around your schedule, so they fit into your project seamlessly, providing a quality service as conveniently as possible. If you need knowledgeable and trustworthy air leakage experts who can provide exemplary results, AF Acoustics is the team you need in Sandhurst.

Registered member of the Air Tightness Testing & Measurement Association (ATTMA)

We are registered members of the ATTMA, a professional association dedicated to promoting technical excellence in air tightness testing and air leakage measurement applications. This means our expertise and quality of services are recognised by the leading air tightness testing body in the UK.

Picking a Time for Your Air Permeability Test

We want you to be able to access comprehensive air tightness testing in Sandhurst whenever you need it. We have responsive scheduling options. Schedule for your air leakage testing at your comfort. You won’t get delays or difficulties when scheduling.

Quick Turnaround on Test Certificates Where Possible

AF Acoustics offers a professional and reliable service; we understand that our clients are keen to get their test results as quickly as possible, to facilitate this process we strive to deliver next-day turnaround on test certificates.

Affordable Prices

AF Acoustics, a small business with low overheads, offers one of the best prices in Sandhurst and guarantees professional services.

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 Sandhurst

We conduct air permeability tests on residential and commercial buildings of all sizes and types. After the test, an ATTMA certificate is given to you. You can find out how much uncontrolled ventilation your building has by testing it for air leakages. 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 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. Excess air leakage causes heat loss, greater carbon dioxide discharge and can make occupants uncomfortable due to the influx of cold air. It also causes wind washing and thermal bypassing, resulting in lower energy performance. Exfiltration/infiltration of air is caused by a stack effect. Due to the pressure difference inside and outside the building, rising warm air reduces the pressure in the base of the building and draws in air, whether through open doors, windows or other openings and leakage points. Air permeability testing is a legal requirement for constructions in Sandhurst. This way, they can have high energy performance, meet building regulations requirements and get signed off by building control. Clients and employees will be at ease in their surroundings. In addition, you get lower heating and cooling costs. A comfortable environment results in a higher productivity rate.

Part L Test

Air tightness testing has been a compulsory part of the Building Regulations for new dwellings, renovations and commercial projects since the revision of Document L in 2006. Air tightness can also be called air leakage or air permeability rate. Although not always seen, air leakage can occur through any gap, space or crack in a building’s fabric. The Building Regulations (Part L) demand that a selected group of different kinds of residential constructions and all non-domestic buildings greater than 500m2 perform air leakage tests. The highest air permeability target set is 10m3/h/m2 but your building might need a much lower one. Air permeability is key in the following areas: i. A construction’s energy performance, ii. CO2 emission targets iii. Building Regulations Part L standards

What Is Part F Test?

We will help you with all your Parts L and F requirements. 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.
Get the mechanical extract fans tested for flow rate. This is what Building Regulations Approved Document F requires. 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. Use method 3 – the minimum benchmark method, which tests extractor fans with vane anemometers. This is our testing procedure.


What Kinds of Air Tightness Testing Services Do We Offer?

Air Tightness Testing has different tiers, depending on how complex a building is and its size. Find them 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. Air tightness testing for dwellings more than 4000m3, except big phased handover/zonal and high rise (LCHR) constructions is done. Level 3: Air Pressure Testing for LCHR buildings, phased and zonal handover buildings is carried out.

Domestic Buildings Testing as Required by Approved Document L1

Air 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 leakage testing is a requirement of Approved Document L1A. Your building may need a lower rate to meet the CO2 discharge target. The required rate can be found in a building’s design-stage SAP assessment SBEM. Too much air leakage leads to heat loss which can lead to draughts and higher energy bills.

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

Air leakage testing is the measurement of uncontrolled ventilation from a building’s fabric. The test results are inscribed using m3 per hour per square metre. Air pressure testing is compulsory, according to Approved Document L2A. The highest air permeability rate for your dwelling when tested should be 10m3/h/m2. The result of your dwelling’s air permeability rate might have to be lower than required due to SAP or SBEM assessment. The air permeability target can be found in a building’s design-stage SAP or SBEM assessment. An excessive amount of air leakage leads to greater energy expenses, heat reduction, carbon dioxide discharge and draughts.

Air Permeability Testing of Smoke Shafts (for 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. When there is a fire, the auto opening vents play an important part in expelling smoke in multi-storey buildings. The performance of the fans and vents depends on the air tightness of the shaft. Air tight shafts have enough pressure difference to extract smoke and save people inside a building during fire emergencies. We’re committed to automatic opening vents builders’ target for air permeability. This enables the vents to work efficiently. An air pressure test is conducted using a fan installed in the shaft. The usual openings are closed off too so that the shaft’s integrity can be determined. Once the test is completed and successful, the automatic opening vents are installed.

We Offer 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. This is done to meet the Building Regulations standard. Make sure the ventilation system is efficient, expels pollutants and odours, and reduces humidity, especially in kitchens and bathrooms. 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.

Particular Test and Building Readiness Operation

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

Gaps and cracks in the building that cause air leakage are often difficult to detect. They may be obscured by the internal building finishes. The most acceptable approach to show that a building fabric is impermeable is to identify leakage paths within it.

At least 20% of different kinds of dwellings in a development have to be tested, according to new regulations; but the reliability of the sample from this type of testing is determined by the types of buildings in the development. There is a penalty for untested constructions. Therefore, we suggest air leakage tests for all buildings.

Pre-Test

The client needs to send our test engineers the drawings of the development (plans and elevations) and target air permeability requirements. An Air tightness test can be done in 30 – 60mins. Wind speed should not exceed 6m/s. Test engineers need to know the size of a building envelope and requirements before coming to the site. To get the site ready, make the place air tight by closing and securing all external doors, windows, ventilation and smoke vents. Remember to turn off range cookers or stoves a day before testing as well as mechanical ventilation systems, and fill all drainage traps.

  • Shut the windows
  • Close the smoke vents
  • Open and secure all inner doors
  • Put off the mechanical vents
  • Close ventilation
  • Fill drainage traps
  • Put off range cookers/stoves a day before the test (if applicable)

Building Envelope Measurement

We 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 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 measured as air leakage per hour per square metre of the building fabric at a pressure differential of 50 pascals (50n/m2). The air barrier envelope area is the total area of all the floors, walls and ceilings both above ground and underground. The internal dimensions of the building found in the drawings are used to calculate the envelope area and subtractions are not made from the areas of floors and ceilings with or without external walls or from the area of the junctions of internal walls.

Air Exchange Rate

Air exchange rate is vital to ventilation design but it isn’t used as the determinant of the actual design or calculation. To calculate ventilation rates for domestic buildings, the area and number of people living in the building are considered.

Cold Roof Envelope Area Measurement

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.

Evaluating a Warm Roof Envelope Area

In a warm roof, an air barrier is inside the insulation which runs on the pitched roof rafters. The envelope area, found at the insulation’s warm side, is the separator between the conditioned internal aspect and the unconditioned.

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.

Site Test Procedure

Evaluate the weather (barometric pressure, wind speed and temperature) Fix a fan to an aperture, usually the door, in the building. Ensure all the testing equipment is ready. Note the air flow volume from the fan. This is the same as the air leakage from the building envelope. Increase the speed of the fan slowly till it gets to 55-60Pa. Record pressure differences across the building at each fan speed.

Calculating Air Leakage

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

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: Lower heating bills due to less heat loss, with potentially smaller requirements for heating and cooling equipment capacities The ventilation system will operate optimally Lower levels of mould due to less moisture collecting in gaps and cavities. Thermal comfort is enhanced because air infiltration is lower. Be assured that you’ll get a test that meets all the regulations and standards no matter how big or small your building is. Not only do we provide services that meet building regulation targets, when you employ our services, you’ll save money and spend less in the long run. We test for air permeability, provide consultancy services and support services and review the designs of all buildings, whether domestic or commercial, large or small.


Good and Best Practice Styles

When constructing a new building, it should be built air tight, as stated by Building Regulations – Approved Document L1A. The regulation is focused on the conservation of fuel and power usage. Part L1A states that any new building must undergo an air pressure test, according to present regulations.

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. 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

England and Wales: Building Regulation Targets Part L 2010

If you’re constructing a new dwelling, you have to comply with Approved Document L1A’s stipulation to test it. Those exceptions only occur when there are two or more dwellings in a development. Three units of a dwelling type or 50% of all examples of that dwelling type should be tested. 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. An SAP assessor can decide which buildings can use the assumed value successfully. A testing procedure required by Building Regulations is expressed in ATTMA TSL1 for dwellings and ATTMA TSL2 for non-dwellings. Air leakage testing is required on all residential developments (this may be a sample of units) and certain Non-Dwellings. Non-dwellings where floor area is less than 500 m2 or has an assumed assessed air permeability rate of 15 m3/h/m2 in their calculations, may not have to undergo the air leakage test.

England and Wales: Building Regulations 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. Minimum Technical Competence (MTC) and National Occupation Standard (NOS) documents are the basis for the scheme.

Air tightness testers can be divided into three categories

  • A single 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 in buildings with 4000m3 and higher. Large high rise and phased handover buildings are excluded from the test except a level three tester is in charge.
  • Air tightness testing for phased, zonal handover, LCHR and multifaceted constructions is carried out by level three experts.

Air Tightness Test Report

Accredited testing companies issue air pressure reports. First, extraction fans are closed. Then, the details and results of the tests are written down in a report. This is done according to the testing organisation’s procedures and Building Regulation standards.

Test Results

We analyse our tests and results for any divergence from the standards required and check the air pressure rate against target rate. That way, our results are expressed in line with test standards. Our reports correctly note the client, air tightness tester, building and address. 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

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

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

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.