What is airtightness testing?

Under TGD L 2019 all new domestic and commercial buildings need an air tightness test when the building is complete. The air tightness test result must be less than 5 m3/hour/m2 @ 50 Pascals to satisfy the building regulations. You might also get an air tightness test when doing a deep retrofit of a building to identify the areas that are most drafty. It can be especially useful when coupled with a smoke test or thermal imaging survey to identify where you are losing heat and if windows are badly sealed

If you have natural ventilation and you get an airtightness test result less than 3m3/hr/m2, your home is too airtight. You need to introduce mechanical ventilation to help deliver adequate fresh air