What is Air Tightness Testing?

Air Testing

Many of us have heard of Air Tightness Testing, or maybe you have been told that you need an Air Permeability test. But what exactly is it? When do you need it? And what is the process of an Air Tightness test? Here we will outline the basic understanding you should have before you begin your research into Air Tightness companies.

What is Air Tightness Testing?

Air Tightness Testing is a recognised method of measuring the extent to which uncontrolled flow of air is lost through the gaps and cracks in the fabric of a building. It is also referred to as Air Testing/ Air Pressure Testing/Air Leakage Testing. 

Air Testing falls under Part L of the Building Regulations and the Scottish Building Standards. England and Wales have had separate building regulations since 2011, however as far as carrying out an airtightness test, there’s no difference.  Reducing air leakage results in reduced heating energy use and lower CO2 emissions and therefore decreases the heating costs associated with the building and improves the occupant comfort. As the government strives to reduce CO2 emissions from new buildings, greater emphasis is on the quality of the fabric of a new building.

Do I need an Air Tightness Test?

Building Regulations require that energy calculations are carried out on all new buildings with all new dwellings being subjected to air testing in compliance with Part L of the Building Regulations and therefore in accordance with ATTMA Technical Standard (ATTMA TSL1) and buildings other than non-dwellings in accordance with ATTMA Technical Standard L2 (ATTMA TSL2). Air testing plays an integral role in ensuring that the energy calculation Building Carbon Dioxide Emission Rate (BER) is less than the Target Emission Rate (TER).

So whether you’re a small developer or a large housing contractor, you will need to perform an Air Permeability test on your new builds before completion.

When should an Air Tightness Test be performed?

Before you request an Air Leakage test, you must ensure that you have met certain requirements and that the properties are in fact, up to a standard of readiness. This includes;

  • All trickle vents fitted
  • Loft hatch fitted
  • Drainage traps filled OR sealed
  • Downlights & ceiling roses fitted
  • External door thresholds complete
  • Mains water feed penetration sealed
  • Masticing required for air seal complete
  • Boiler flue penetration sealed
  • Extractors fitted & sealed
  • SVP penetration to loft space sealed
  • All windows closed
  • 240v or 110v power to dwelling

If you have completed the above lists and are confident that all has been done up to a high quality standard, you are now ready to perform an Air Tightness Test.

What is the process of an Air Tightness Test?

Before the test takes place, you will need an initial assessment (usually free) to establish your air testing requirements. 

On the day the process is very straightforward and our experienced engineers will get to work right away. Although hard to understand, the basics of the process you need to know are as follows;

  • A fan is used to pressurise the test area (this can be either a positive or negative air pressure)
  • This allows a building differential pressures to be obtained and a pressure across the fan to be obtained
  • The data is collected across a range of pressures, ensuring that readings greater than 50Pa test pressure is obtained
  • The building differential pressures are adjusted for the building condition in its resting state (wind and stack effect) and the calculated fan flows are adjusted for environmental factors
  • The adjusted building differential pressure is plotted against the adjusted calculated fan flow on a logarithmic scale to identify the air permeability at a test pressure of 50Pa

This test procedure would normally take no longer than an hour to perform after setup and once complete, you will be issued with an on-site draft certificate.

Air Tightness Testing is a necessity for all new build developers and requires consideration at all stages of the build process with the final test being undertaken at completion stage. If you are in need of an Air Permeability test or would like to understand more about the process, please give us a call and we’ll be happy to discuss your specific requirements.

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