Air Tightness Testing

What we do

Air Leakage Testing Ltd has a team of experienced test engineers registered with ATTMA to provide air testing for Part L1A (new dwellings) and Parts L2A and L2B (new buildings other than dwellings):

House and flats

Schools and hospitals (including isolation facilities to BTS 3/2018)

Care homes, student accommodation


Industrial units, warehouses, distribution centres


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.

We also offer advice and support on achieving air tightness through design reviews, site inspections and tool box talks/demonstrations on early completion tests. 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.

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

Smoke shaft integrity for automatic opening ventilation

Identifying ingress paths e.g. smells between flats, houses or units


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 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.

How it works

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

We provide a checklist and agree a date

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.

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

We issue ATTMA certificates for each test.

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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