Air Testing & Consultancy

Our Air Tightness Testing Services

Air Leakage Testing Ltd has a team of experienced test engineers registered with ATTMA to provide a comprehensive air tightness testing and consultancy service, including air testing for Part L1A (new dwellings) and Parts L2A and L2B (new buildings other than dwellings), as well as Passive House and other Low Energy schemes.

NB: New versions of Approved Document L have been published and will start to take effect from June 2022.

  • Schools and hospitals for Approved Document (AD) L2 (including for HTM-03 for isolation, operating, pharmacy septic preparation, containment and similar facilitiies to BTS 3/2018)
  • Care homes, student accommodation, hotels (AD L2)
  • Offices, Retail, Restaurants, etc (AD L2)

In addition, we are able to undertake air pressure testing for other purposes including:

  • Identifying ingress paths e.g. using air and smoke to trace the path of smells/smoke between flats, houses or units

We also offer advice and support on achieving air tightness in advance of undertaking the test, including:

  • Desktop design reviews – a review of the key design details that make up the air barrier
  • Attendance of design meetings
  • Pre-test inspections and reports – walking the building with the site team to review the air barrier and identify potential issues/soultions, plus agree pre-test preparations and practicalities of the test (timings, access, etc)
  • Toolbox Talks

In addition, if buildings fail to achieve their targets, our engineers can demonstrate and explain the issues onsite using the test equipment and/or smoke, report the issues using photographs and snagging sheets then assist with identifying appropriate solutions.

If the building is only a little over the target, it is usually possible to identify the issues and wait for the leakage paths to be sealed so the test can be repeated on the same day.

Air Testing Requirements

Air Tightness testing is a requirement for all new buildings. Testing must be conducted by a competent person, typically a company registered with the Air Tightness Testing & Measurement Association (ATTMA).

Air Tightness is a key factor in achieving an energy efficient building fabric in combination with insulation. The England & Wales Building Regulations require air tightness to be measured through site testing.

Part L is Changing

From June 2022, a revised version of Approved Document L will come into force. It is divided into Volume 1 for dwellings and Volume 2 for buildings other than dwellings. There are some significant changes included in this revision in order to achieve a 31% reduction in carbon emissions from new buildings, this impacts a wide range of aspects energy efficiency including insulation and fuel types as well as air tightness, as a stepping stone to the Future Homes Standard in 2025.

The highlights with respect to air tightness include:

  • No sampling – all units must be tested
  • Maximum air permeability reduced from 10 m3.h-1.m-2@50Pa to 8 m3.h-1.m-2@50Pa (i.e. less draughty)
  • A different test standard (CIBSE TM23)

Our Air Testing Process

Our Air Test Engineers are home-based and well-placed to cover Greater London and the City, Kent, Essex, Surrey, Sussex, Hampshire, Berkshire, Buckinghamshire, Hertfordshire and Bedfordshire, we are able to test all over the UK.

Our process is as follows:

1. Answer any queries

  • We are happy to talk through what is involved, what to watch out for and when to test.
  • We can provide guidance and checklists.

2. Price & Date

  • We provide an indicative price based on the size of the building and location, ahead of issuing a formal quote¬†based on PDF drawings.
  • We can look at penciling in dates to suit your programme, our lead times are typically 1-2 weeks but we can often fit in single tests at shorter notice.

3. Preparation

  • We confirm a date
  • Our engineer will call you ahead of the test date to talk you through the preparation and process and agree the timings.
  • We would also look to confirm the air permeability that has been targeted in the energy model (SAP) at this stage, if it hasn’t been discussed already. The results of the test are a key component of the calculation of the overall energy efficiency of the building and, therefore, achieving the necessary air tightness is a critical part of building control sign-off.

4. On the day of testing

  • On houses and flats we would typically complete the temporary sealing for the test when we arrive on site. For larger buildings, we would talk you through what would need to be done in advance of our arrival.
  • We conduct the test. Testing is done through a pressure test whereby fans are installed into a doorway of the building and used to create a measurable difference between the pressure inside and outside of the building. The amount of air needed to maintain this difference can be used to indicate the volume of air escaping through the fabric (what would be draughts in the building’s day-to-day life).
  • If the building doesn’t achieve its target at the first time of asking, we can use our equipment to identify the leakage paths. If these can be addressed relatively quickly, then we can repeat the test on the same day. In order to achieve increasingly challenging energy performance targets, air tightness requirements are becoming tighter. Typically, a good level of air tightness can still be achieved with excellent attention to detail in the decorative finish but, to achieve tighter targets, consideration must be given to air permeability within the design of the fabric, including use of membranes and tapes to maintain the air barrier – please see FAQs

5. Paperwork

  • We issue ATTMA certificates for each test within 24hrs of the test but we can issue them on the same day (when requested).

The below checklists can be downloaded and used to manage air testing from design/planning, through construction to preparation for the test:

Reasons to choose ALT

  • Helpful – we work with you to achieve the best result, identifying potential issues and repeating the testing once these have been addressed. We are on hand to answer any questions before, during and after the testing
  • Knowledgeable – we have been air testing since 2002 and all our test engineers have a vast amount of experience
  • Flexible – we try to fit in with the dates and times you need the test, we try to work around other trades to minimise disruption on site
  • Responsive – we issue quotes and certificates within 1 working day, our lead-times are typically around a week but we will try and fit you in sooner if required
  • Great value – our prices are very competitive but we can also undertake air and sound testing on the same visit to save you more money. If you do manage to find the testing cheaper, we will beat any quote.

How can we help you?

Call 01799 540220 – or send us a message

© Air Leakage Testing Limited 2020

7 Lawson Way, Aylesbury, Buckinghamshire, HP18 0UW

Tel: 01799 540220 – Email:

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