01621 810231

How to Pass a Test First Time | Air Tightness Testing

An Air Tightness Test, (which also might be referred to as an air leakage, air permeability or air pressure test) is a government mandated property test which makes sure that properties aren’t leaking air and wasting heat and energy.

It’s a requirement that new properties are tested, and knowing how to pass it first time can make the difference between finishing a project on time or running weeks late, whilst also saving a lot of money. Here’s how you do it:

The Air Tightness Regulations you have to meet

According to Part L1A of the building regulations, the maximum air loss is 10m3/hr/m2, when set to a pressure of 50Pa.

Best practice on the other hand recommends an air tightness of 7m3/hr/m2.

If you’re in Scotland, they have stricter regulations, with the maximum figure sitting at 7m3/hr/m2, for all dwellings.

Passing an Air Tightness Test, the first time out

How do you actually pass an air tightness test? Thankfully, it’s actually pretty straightforward in principle, but relatively involved in practice. Here’s a simple checklist that you should work down to make sure you’re ready.

  • External structure should be completed, including walls, ground and roof. This includes the doors, windows and all cladding.
  • Fixtures and fittings should be installed, including sockets and lights.
  • Plumbing work is installed and complete.
  • Any service pipes that pass through the structure are sealed.
  • Skirting boards are correctly fitted, as well as sealed at the top and bottom.
  • Areas without skirting boards should be sealed with expanding foam at the point of contact.
  • Any entry into roof voids, eg. loft hatches and storage doors, are fit with draft excluders.
  • Any property services (electric cables, pipes, etc) must be boxed in and sealed.
  • Garage doors are fitted with a draft excluder.
  • One door to the property must be at maximum 2.25m x 1.1m, so that the test can be carried out

During the test, existing ventilation systems should be sealed by the persons carrying out the test, so you don’t have to be concerned with sealing these off.

When is the best time to test?

According to the Air Tightness Testing Measurement Association (ATTMA,) 70% of tests are failed because the testing is performed too early.

The best time for your test is after all the building work is complete. So make sure all snagging is done, and the property is fully connected to the local amenities, but before any finished flooring or furnishings are put in.

Remember, by following these simple principles, you’re far more likely to pass your test first time, and avoid any unnecessary issues in the long term.

If you’re concerned about failing, you should read our guide on the ten most common reasons for failing an air tightness test, which you can find here.

iATS Registered and UKAS Recognised


We are registered with iATS (Independent AirTightness Testing Scheme) and use equipment calibrated by UKAS laboratories. Our testing procedures are also recognised by UKAS.