Domestic Air Tightness Testing

 We provide competitively priced air tightness tests and consultancy services for all types of residential development.


From a single dwelling to large scale residential developments, our highly experienced team of Air Tightness Technicians are able to advise on the initial design strategy of a building, to preparing for and undertaking the final air leakage test(s) on-site.


Don’t let building compliance hold you back, book your Air Tightness Test with EPS Group today.

EPS Group: Expert Air Tightness Testing and Consultancy for Residential Developments

Air Tightness Testing is a method for measuring the amount of conditioned air that is unintentionally lost from the inside of a building as a result of unsealed gaps or cracks within the thermal envelope of the property (also known as air leakage or air infiltration). In straightforward terms, the procedure can be viewed as a way of measuring how ‘draughty’ a property is.

Often referred to as Air Pressure Testing or Air Leakage Testing, each test is completed in strict accordance with a standardised methodology detailed within a Technical Guideline known as ATTMA TSL1 Measuring Air Permeability of Building Envelopes (Dwellings) by an accredited Air Tightness Contractor.

For more information relating to Domestic Air Pressure Testing please explore the Frequently Asked Questions below and our graphic highlighting common sources of air infiltration within a residential building.

To discuss your Air Tightness Testing requirements further, please contact us on 0115 7270599 email us at, or complete our enquiry form.

Why is Air Tightness Testing required in Domestic Properties?

Apart from causing discomfort to occupiers, excessive air leakage increases the energy demand of buildings and therefore, the levels of carbon dioxide (CO2) emissions arising from occupation.

As part of the Government’s drive for improved energy efficiency and for reducing carbon dioxide emissions from the built environment, Air Tightness Testing was introduced to Part L1A of the Building Regulations in 2006 (as applicable to newly built domestic properties).

Asides from the standard requirements of Building Regulations, a number of self-builders and other property owners, also undertake voluntary Air Tightness Testing as part of broader environmental or sustainability certification schemes such as Passivhaus or BREEAM.

Common Sources of Air Infiltration in Domestic Properties

Domestic Air Tightness Testing FAQs

How is an Air Tightness Test Completed?

  • The Air Test is completed towards the end of the construction of a property when the internal envelope is complete, and all services are connected.
  • Prior to running the Air Tightness Test, the Technician will prepare the dwelling by sealing off (masking) any intentional (controlled) sources of ventilation such as extract fans, cooker hoods, trickle vents and log burners and by ensuring that all drainage waste traps contain water.
  • A UKAS calibrated fan (or fans) is temporarily placed within an external door to the dwelling before a number of measurements, and environmental readings are then taken. The property is then pressurised, or de-pressured and a range of readings are recorded at various pressure differentials.
  • Once the fan is running, the actual pressure test generally takes around 20 minutes, and results are available instantly. However, at EPS Group, we allow up to 2 hours to complete a test in order to ensure that there is an opportunity to address any unexpected problems that may arise.
  • During the course of the test, site workers or occupants can remain within the building without any health risks; however, it is important to note that individuals are unable to enter or exit the property whilst the test fans are running, and the unit is pressurised.

What Air Permeability Rate is required to pass an Air Tightness Test?

Approved Document Part L1A of the Building Regulations allows for a maximum air permeability rate of 10.00 m3.h/m2 per tested dwelling.

It is worth noting that this relatively generous air leakage rate is a maximum ‘backstop’ value, which is often superseded by a lower ‘target’ value detailed within the dwelling’s corresponding Design Stage SAP Calculation.

As a result of the increasingly stringent standards required to pass a SAP Calculation, it is a commonplace for target air permeability rates to be set at around 5.00 m3.h/m2 per tested dwelling.

Do all new build dwellings require an Air Tightness Testing?

The current edition of Approved Document Part L1A of the Building Regulations states that as a minimum Air Tightness should be completed on 50% of all instances of particular ‘dwelling type’, or a minimum of three units of each ‘dwelling type’, whichever is less. The following table summarises this test frequency:

Number of Similar Units Within a ‘Dwelling Type’

Minimum Number of Tests Required

1 or 2


3 or 4


5 or more


For different dwellings to class as being the same’ dwelling type’ they should have:

  • The same generic build form (e.g. detached house, end-terraced, mid-terraced, semi-detached, ground floor flat, top floor flat, bungalow etc).
  • Include the same number of storeys
  • Have the same Design Air Permeability Rate (Air Pressure Test Target)
  • Have a similar adjacency to unheated spaces such as garages, unheated stairwells etc.
  • Have the same principle construction details
  • Have a similar number of penetrations, for example windows & doors
  • Have an envelope area that does not differ by more than 10%
  • Please note that the sample testing requirements described above are the minimum ‘backstop’ requirements of Approved Document Part L1A of the Building Regulations and that any dwellings that are not tested are subjected to an increased air permeability ‘penalty’ of +2 m3/h/m2 of the sampled result within their corresponding SAP calculation.
  • The air permeability penalty can often cause the SAP calculation of a sampled property to fail, and as such, there is an increasing trend for developers to seek individual air tightness tests on all units within a development.

How Do I Pass an Air Tightness Test?

In order to have the best chance of passing an Air Tightness Test, we would recommend that you spend time ensuring that that the following common areas of air infiltration are well sealed before scheduling a pressure test. These areas are listed below and highlighted within the adjacent illustration:

  • Wall to floor junctions (below skirting boards)
  • Window and external door apertures
  • Pipework and drainage penetrations (soil stacks, waste pipes, water pipes, heating pipes)
  • Behind Kitchen/Utility units or fitted bedroom or bathroom furniture.
  • Under baths and shower trays
  • Around sockets and other electrical points.
  • Loft hatches
  • Bulkheads to loft storage voids

Whilst we are unable to guarantee that you will pass the Air Tightness Test, we allocate time within our appointments to allow our client’s an opportunity to undertake any permanent remedial works that we may identify during the course of the test.

How can EPS Group help with Domestic Air Tightness Testing?

There are many reasons to appoint EPS Group to provide your Domestic Air Tightness Testing

How can EPS Group help with Domestic Air Tightness Testing?

We pride ourselves on providing a client-focused Air Tightness Testing service. We allocate time within our appointments to allow an opportunity for any unexpected remedial works to be completed in order to provide the best possible chance of achieving a pass certificate.

We have been providing Air Tightness Tests since 2007, and all of our Technicians are vastly experienced with pressure testing all types of dwellings ranging from modest studio flats to large scale mansions. We are also accustomed to testing all types and sizes of commercial buildings, meaning that we are ideally placed to complete air tightness testing on mixed-use development.

There are many other reasons to appoint EPS Group to complete your Air Tightness Test including:


Highly Competitive Fees with substantial discounts for multiple tests.


All of our Technicians are accredited members of The Independent


Airtightness Testing Scheme (iATS)


Flexible Test Appointments Including Weekends


Domestic & Commercial Units Tested

EPS Group: A Partner for those in the Construction Industry

We value the importance of a solid working relationship with those in the construction industry, and for many, we serve as the reliable go-to-company to entrust from the planning stage of a development through to completion.

What Our Clients say:

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Let’s discuss your Domestic Air Tightness Testing project!

Jual Ahmed
Jual Ahmed
Excellent service from start to finish. I would highly recommend and will definitely use again. Thank you!
A great service and attended within a week of request. Polite knowledgeable engineer who completed the test quickly and efficiently...Thank you EPS
Steve Naylor
Steve Naylor
EPS group undertook the initial SAP design assessment, then the as-built assessment for my new property, including air test. They were super-responsive and made the appointment for the air-test within a few days of the request. The certificates were issued very promptly and they helped me through the process (I had never done this before). Really recommend them.
Nick Collingridge
Nick Collingridge
Great service from EPS Group. Their operative was friendly, efficient and very helpful. He carried out his survey quickly and then spent time walking round the property with me pointing out all the points at which air was infiltrating. He also passed on some invaluable tips about the best way to attend to the detailing of aspects of a property's structure to maximise air tightness. I am altogether very satisfied with the survey.
Mark Blood
Mark Blood
Have worked with EPS for several years now in connection with all of our energy assessment requirements. Extremely efficient service at very competitive fees and always available to offer advice on achieving compliance. Would definitely recommend.