Air Tightness Testing for Energy Efficiency

Air tightness testing measures draughts which have a significant impact on energy efficiency in new and existing residential and commercial buildings

Our experienced test engineers are registered with ATTMA, and are available to provide a comprehensive air tightness testing and consultancy service.

Types of air testing services


Air Tightness testing is a requirement of Approved Document L (Volume 1) for all new houses and flats. Testing must be conducted by a competent person, typically a company registered with the Air Tightness Testing & Measurement Association (ATTMA). All of our test engineers hold ATTMA Level 1 registration.

Air Tightness testing is a requirement of Approved Document L (Volume 2) for all new buildings that are not dwellings. Testing must be conducted by a competent person, typically a company registered with the Air Tightness Testing & Measurement Association (ATTMA). We have a number of experienced test engineers with ATTMA Level 2 registration and a lot of fans and which allows us to test all types and sizes of building.

PassivHaus, EnerPHit, AECB and similar low energy schemes prioritise the importance of the building fabric being well insulated and airtight so that other energy saving measures/design can be fully effective. We undertake air tightness testing of Low Energy houses, apartment blocks and commercial properties. Our test engineers are ATTMA registered for Low Energy Scheme air testing.

Air Tightness is a key factor in achieving an energy-efficient building fabric in combination with insulation.  Improved air tightness means reduced heat loss through draughts which makes the buildings cheaper to heat and more comfortable. Our experienced engineers are able to test existing buildings before and after refurbishment/retrofit as well as identify leakage paths and offer guidance on remedial measures.

Our Air Leakage 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, Oxfordshire, Hertfordshire, Bedfordshire and Cambridgeshire, we are able to test all over the UK.

1. Answer 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.

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

Download  – Dwelling checklist

Download – Guidance for Housebuilders

Download  – Non-dwelling checklist

2. Date & Price
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 pencilling 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 plus agree the timings. We would also look to confirm the air permeability that has been targeted in the energy model (SAP/SBEM) 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.

On commercial buildings and large residences, we would talk you through what would need temporary sealing would need to be done in advance of our arrival.

4. On the day of testing

On smaller houses and flats we would typically complete the temporary sealing for the test when we arrive on site. On commercial buildings we would talk through with the site team how the taping of ventilation would need to be completed.

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).


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

  1. Desktop design reviews – a review of the key design details that make up the air barrier
  2. Attendance of design meetings
  3. Pre-test inspections and reports – walking the building with the site team to review the air barrier and identify potential issues/solutions, plus agree pre-test preparations and practicalities of the test (timings, access, etc)
  4. Toolbox Talks
  5. Preliminary/benchmark testing at an early stage to confirm performance and identify leakage paths


We also carry out air tightness testing for other purposes, including:

  1. Smoke shafts for smoke ventilation
  2. Plenums/raised access floors
  3. Hospital isolation areas – Isolation suites, operating theatres, etc
  4. To identify the source of smells/smoke


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.

What our clients say about us

“ALT were extremely helpful and knowledgeable. They worked with the site team to identify and resolve issues during construction.”
“I have used Air Leakage Testing Ltd on two separate occasions at my property and found them to be extremely thorough and professional at all times. The turnaround between site visit and subsequent reports was quick and efficient - making my life a whole lot easier! Would highly recommend to anyone!”

Established in 2002



Helpful Engineers

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.

Flexible & Responsive

We aim to fit in with your chosen dates and times, to work around other trades and to minimise on-site disruption. Our lead times are typically a week but it may be possible to fit you in sooner. We issue quotes and certificates within 1 working day.


We have been air testing since 2002 and keep pace with changing regulations. All our test engineers hold ATTMA L1 registration and have considerable experience in undertaking tests and resolving potential issues.

Great value

Our efficient processes help us to offer very competitive prices. In addition, we can undertake air and sound testing on the same visit to save you more money. If you do receive a cheaper air testing quote, we will beat it.

Get a quote

Complete a few details about your project and we will provide an estimated cost. Provide more information and we will issue a formal quotation.