Air Tightness Testing

Air Tightness Testing2018-06-20T15:25:15+00:00

Need to comply with Scottish Building regulations on air tightness? Looking for a local air tightness tester? Need some free advice?

We undertake air tightness testing (sometimes known as air leakage testing or air pressure testing) to comply with the requirements of Section 6 of the Scottish Building Standards. We use calibrated Retrotec equipment to de-pressurise a building and record air flow measurements.

Air Permeability Certificates can be issued within 24 hours – or if poor air tightness is detected, we can use our high-resolution thermography equipment and smoke testing to locate areas of costly air leakage to allow remedial work to be undertaken.

What is Air Leakage?

Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric of dwellings (sometimes referred to as infiltration, exfiltration or draughts). This is not to be confused with ventilation, the controlled flow of air into and out of the dwelling through purpose-built ventilators that is required for the comfort and safety of the occupants.

Excess air leakage leads to unnecessary heat loss, discomfort from cold draughts and increased energy costs.

Standards for air leakage?

Air leakage is quantified as air permeability (q value). This is the rate of leakage expressed in cubic metres per hour per metre of envelope area (m3 /hr / m2) in or out of the dwelling. It is measured at a reference pressure difference of 50 Pascals (Pa) by a fan pressurisation test.

When to Test?

In our experience the most common reason for new dwellings failing an air tightness test is for being “too air-tight”, with only natural ventilation (trickle vents) specified. Please check this with your architect/SAP Assessor prior to commencing your build.

Air Tightness Test – FINAL TEST Pre-test Checklist

For the final air test, the building should be complete and ready for occupants. Specifically:

  • All windows and external doors in place, and fitted with draught strips where required;

  • All windows and external doors in place, and fitted with draught strips where required;

  • All skirtings in place, all mastic completed around windows and skirtings to design specification;

  • Openings around pipe penetrations sealed to design specification;

  • Loft hatch in place with draught strip to design specification;

  • All sockets in place and screwed to wall;

  • All access panels to pipe chase in place;

  • All lighting in place, and in the case of down-lighters ‘pushed in’ to final position i.e. these are sometimes pulled out for decorating;

  • Boiler & stove flue pipes in place, and sealed to design specification;

  • Trickle vents should be closed but not sealed;

  • If applicable MVHR ventilation system should be switched off and sealed (externally is often easiest)

  • Please have a copy of the latest SAP calculation available (or e-mail to in advance)