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Air Tightness Test
The purpose of undertaking the air leakage test is to prove compliance with Building Regulations.
You are obliged to undertake one test only, but if you are building a very airtight house with a mechanical ventilation system installed, it might make sense to do two tests in conjunction with advice from your designer/builder.
The first would be done at the first fix stage once the initial airtight layer is installed to determine its quality and benchmark it against your design specification.
An air leakage test at the first fix stage is very cost-effective. Since the final layers of the house are not in place, finding and fixing the leaks is easy and inexpensive.
If your compliance or the functionality of installed mechanical ventilation systems requires a good outcome (e.g., ≤ 3 air changes per hour at 50 Pascal pressure differential), then it makes sense to do two tests.
If the house does not perform as designed, particularly where a mechanical ventilation system has been installed, it can never operate efficiently – wasting your money.
When we undertake an air leakage test, we do so to the highest standards (IS EN ISO 9972:2015) and in accordance with NSAI specifications and INAB Certification.
2eva staff undertaking air leakage tests are highly trained and experienced and will work with you to maximise your test outcome.
We often visit the site before the first set of tests to meet the air tightness champion and walk the buildings to be tested to identify visual flaws before testing. This is a win-win situation for the client and us, as it means that the actual testing process works better and ensures better outcomes.
As we are testing under the demanding NSAI Standards, we will test the building using both positive and negative pressure to achieve a minimum pressure difference of 50Pa.
The outcomes will be reported for both the air changes per hour rate and the air permeability rate required by the Building Regulations.
​Understanding Air Leakage Testing Requirements and Standards
As a builder/developer you have an obligation under either the 2011 or 2019 Building Regulations to complete tests to a defined minimum standard. This will depend on whether the project had Planning Applied for before or after 31st October, 2019.
This will have an impact on two key elements of your obligations – the first being the maximum upper limit you have to test to:
≤ 7 m³ h m² under the 2011 Building Regulations
≤ 5 m³ h m² under the 2019 nZEB/Building Regulations
The second is the number of air leakage tests that must be performed on the project. If dwellings are being completed under the 2011 Building Regulations, they are subject to the minimums set out in the Sample Regime that we can explain to you, but if under the 2019 nZEB/Building Regulations, each and every dwelling has to be tested.
We have vast experience working closely with our business partners to ensure that we maximise the outcomes on-site when undertaking air leakage testing. Our experienced colleagues work with your team before we ever get to the site to discuss how to prepare the building and the best methodology to employ.
Comprehensive Air Leakage Testing Services and Compliance Verification
If you are building a scheme of houses, then there is a requirement for a sample number of houses to be tested in line with Table 4 of the Part (L)
However, if one of the critical factors of your DEAP calculation for your BER depends on an input value lower than the backstop value of 7 m³/hr/m², then a test must be performed on each dwelling to prove the input value.
The n50 is the air change rate at and is expressed in air changes per hour (ac/h). It is the relationship between the total volume of air in m³ and how often leaks in the
building envelope allows the air to exchange at 50 Pascals air pressure difference.
The q50 is the air permeability rate and is expressed as m³ h m². It is an expression of the amount of air leaked from the dwelling in relation to the total exposed surface area
of the building (i.e., the ground floor, all exposed ceilings, and all external walls [including party walls/floors in the case of semi-detached, terraced, or apartment dwellings) at 50 Pascals pressure.
All tests we undertake are done to the highest standards (I.S. EN ISO 9972:2015) and in accordance with NSAI specifications.
The results of the air leakage test on each dwelling will be provided in a report in accordance with NSAI standards, and the outcome can be inputted into the final DEAP calculation to verify Compliance with 2011 Building Regulations or 2019 nZEB/Building Regulations.
Types of Air Tightness Test
Air leakage tests happen when a pressure difference of typically +/- 50 Pascals (Pa) is generated between the inside and outside of the building compared to natural air pressure using a fan suitable for this purpose. This can be either under pressure (i.e., air is pulled out of the building) or pressure (i.e., air is blown into the building) and, ideally, a combination test of both.
Air tightness testing equipment can be used in several ways.
The standard air tightness or blower door test requires that a single fan be set up in a doorway into an expandable frame that fills the doorway. Onto the frame is mounted a canvas-type membrane or cloth with a hole in it. The testing fan is then fit into the frame/cover and operated using bespoke software, generating positive and negative pressure as required. A single fan will normally be enough for a single dwelling.
The process is operated by a skilled, trained, and experienced operative. The operative will have the desired mix of onsite practical experience and the training to operate the equipment and advise clients of the location and severity of leaks.
Where suitable, as the picture to the right shows, we can use smoke to demonstrate the location of leaks—in this case, via a window slider.
Air Tightness Test FAQ
Frequently asked questions
