Air Tightness Testing

WHAT IS AIR LEAKAGE?

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

What Is Air Tightness Testing?

Air tightness testing, sometimes also called air pressure or permeability testing, calculates the amount of uncontrolled air leakage through gaps and cracks within the fabric of your home or business property.

Thermal Image UK perform air tightness tests throughout Scotland, the North of England and further afield. We use calibrated Retrotec equipment to pressurise and/or de-pressurise a building and record air flow measurements. Our air tightness tests comply with the requirements of Section 6 of the Scottish Building Regulations Technical Handbook and Part L of the Building Regulations (England and Wales) for domestic and commercial buildings.

Image showing air tightness testing equipment

WHY IS AIR TIGHTNESS IMPORTANT?

Save Energy & Money

Improving the air tightness of a building will reduce uncontrolled heat loss and result in more efficient heating and cooling systems, so lower fuel bills and less CO2 emissions - a win for the environment and energy budgets.

Comfort for Occupiers

Addressing the air tightness of a building can vastly improve indoor air quality with better control over temperature and humidity levels, reducing draughts, sound pollution and mould build-up. Well-ventilated but air tight buildings provide a healthier living and working environment.

Building Protection

Significant damage can be caused by moisture which leaks into the fabric of a building and then condenses resulting in cold spots, mould, damp, rot and even structural damage. An air tight building is a durable building!

Image of an air tightness test being carried out.

HOW WE CAN HELP

Thermal Image UK have years of experience carrying out air tightness tests, from early advisory tests to those required for final certification. We can talk you through the process from start to finish, including advising on common reasons for a building to fail a test – in our experience, the most common reason for a new dwelling to fail an air tightness test is because is it “too air tight”. This usually occurs when there is only natural ventilation (eg trickle vents) specified in the design. We recommend you check this with your architect/SAP Assessor prior to commencing your build. In some circumstances (such as Passivhaus buildings, where a very high level of air tightness is required), you may wish to carry out an interim test before the plasterboard is installed, allowing any problem areas to be identified and fixed while access is still possible. You can expect a quick turnaround from your first contact with us to when we conduct the air tightness test

How we perform air tightness tests

Initial Contact

When we receive your enquiry we will discuss your requirements by phone or email. We may need some additional information from you, such as floor plans for the building, to provide you with an accurate quote for the work.

Site Visit

We will often conduct a site visit, especially for larger or more complex buildings, prior to providing a quote. This enables us to assess the scope of work and discuss actions to ensure the building is prepared for testing. When required, a method statement and risk assessment will be submitted ahead of the test. Tests are scheduled according to your preferred schedule and prevailing weather conditions.

Testing

Our air tightness tests are conducted using calibrated Retrotec blower door fans at 50 pascals pressure difference. By taking a series of air flow measurements we calculate the airflow rate into/out of the building. Using that number and the building’s volume or envelope area, we calculate the air leakage rate. The design target for newbuild dwellings is typically 5 or less. The higher the number, the more leaky the building! We can issue Air Permeability Certificates within 24 hours of the test.

Recommendations

If your building fails the air tightness test, we have extensive experience of working with onsite teams to investigate and identify areas that leak air excessively – we are one of few companies to combine air tightness testing with thermal imaging and smoke testing to do this. If the issues identified can be resolved quickly, we are often able to re-test the building on the same visit.

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Is Your Property Ready For An Air Tightness Test?

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 plasterboard/gyproc in place and sealed/taped as required

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

All kitchens and bathrooms installed and sealed 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. Wood burning stoves and AGAs etc. should not be lit at the time of the test.

Trickle vents should be closed, but not sealed.

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

Please advise the target air permeability of the dwelling/building in advance of the test.

We appreciate that sometimes all of the above cannot be completed at the point when the test is to be carried out. We will try to accommodate this, but you must email Tom Barbour in advance ontom@thermalimageuk.co.ukto discuss.

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