Air Tightness Testing

Need an air tightness test?

Air Leakage Testing offers a quick, easy and low-cost solution.

Our experienced test engineers will undertake testing with minimal disruption and provide next day certification.

Established for 20 years, Air Leakage Testing is a Contructionline Gold company, providing:

  • ATTMA L1 registered testing for newbuild flats and houses
  • ATTMA L2 registered testing for industrial units, schools, hospitals, offices, care homes, hotels and any other type of building other than a dwelling that needs testing for Energy
  • ATTMA L4 registered testing for PassivHaus and other low energy schemes
  • Air testing of smoke shafts for automatic opening vemtilation
  • Air testing of plenums/raised access floors to BG65
  • Air testing of isolation suites
  • Air testing for existing buildings that are looking to improve energy efficiency

We are best placed to provide results you can trust and that Building Control will accept without question.

Need a quick turnaround?

We can undertake air tightness testing on multiple units in a single visit to minimise disruption and keep costs down. We have sufficient fan capacity to test buildings of any size.


For large buildings (e.g. distribution centres), we use Blower Door Fans, in banks of up to 6 in a doorway (rather than trailer-mounted fans). This solution offers the same capacity, without the need for bespoke templates and time-consuming installations. This reduces time on site and costs.

Need Technical Advice on Air Testing?

Our test engineers are based across the South East so are conveniently located to work with builders across the Home Counties and London.


If you are unfamiliar with the testing process, we will guide you through it. Let us help you to get your buildings to comply.

What if a Building Fails an Air Tightness Test?

If a building fails to meet the Air Tightness targets our test engineers will identify the air infiltration paths while on-site and smoke can be used to demonstrate leakage at a high level.


With a clear diagnosis and our solutions-focused advice, issues can be addressed.

Get a Quote

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We won’t be beaten on price!


How it works

  1. We provide a quote based on the size of the building and location – it is usually helpful to have PDF Plans to calculate the size of larger buildings
  2. We provide a checklist and agree a date
  3. We 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 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 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.
  5. 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).
  6. 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.

Why use 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.


“ALT were extremely helpful and knowledgable. They worked with the site team to identify and resolve issues during construction.”

James Selby, Quality Manager, BAM Constuction Ltd.

“Always found ALT helpful, proactive and reliable, they is why we have used them for sometime now”

Justin Skipper, Midas Structural

01799 540220

Enquire about Air Tightness Testing

Air Leakage Testing Limited


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