Commercial air leakage testing

Commercial air leakage testing

An air leakage test is a test to determine the level of uncontrolled air flow through gaps or cracks in the fabric of a building. The result of the air leakage test is expressed as a quantity of air leakage (m3 per hour) per square metre of building envelope.

Air leakage testing is a requirement of Approved Document L2A. Each building tested must achieve a maximum air permeability rate of 10m3/h/m2. In order to comply with the carbon emission target it may be necessary to achieve a lower air permeability rate. The required air permeability rate for each building can be found on the design-stage SBEM report for that building.

Too much air leakage leads to unnecessary heat loss (and consequently, higher CO2 emissions) and can lead to discomfort to the occupants through cold draughts.


How Energytest can help

ATTMA registered – As registered members of the Air Tightness Measurement Association you can rest assured that our air leakage test certificate will be accepted as evidence for Building Regulations sign-off.

ACCREDITATION – large buildings may need to be tested using multi-fan systems. This testing should only be undertaken by companies such as Energytest, that hold a “level 2” accreditation.

EXPERIENCE – Our air test engineers have experience of carrying out successful air leakage tests on buildings of all types and sizes.

SUPPORT – For added piece of mind our air test engineers will be happy to assist you with free advice throughout the construction process.

RELIABLE – Building Regulations sign-off is often time-constrained and stressful. We shall attend site at a time that is convenient for you and provide certificates within 24 hours of the test.

QUALITY – By using an ISO 9001 accredited organisation such as Energytest you can be confident in receiving a consistently high quality of service.

SAFE – Like you, we take health and safety seriously. All of our engineers are CSCS certified.

SINGLE-SOURCE-SOLUTION – As well as your air leakage test we can provide SBEM calculations and Energy Performance Certificates.

For buildings with a total heated floor area below 500m2, it may be possible to avoid the need for any pressure testing by using an assumed value of 15m3/h/m2 within the BER/TER calculations. Your SBEM assessor will be able to confirm if this is the case for your building.

  1. The integrity of the structure must be complete prior to the test. Please see “How can I improve the air tightness of a building?” below.

  2. Our engineer will need access to an external door (approximate size 2.1m high x 0.9m wide) and an electrical supply within 25 metres of the doorway.

  3. All controlled ventilation openings will be sealed with polythene sheet or self-adhesive tape during the test. These include mechanical ventilation fans, window trickle vents and open flues/chimneys.

  4. All exterior doors and windows must be kept closed during the pressurisation tests. The actual test (after set up) is usually completed in well under one hour. During this period no personnel should enter or exit the building. It is preferable that the building is unoccupied.

The majority of buildings tested achieve a first time pass. However, should this not be the case we shall advise you of all points within the building where leakage was detected, and remedial work is required. If it is possible for the remedial work to be carried out at once we shall allow a reasonable amount of time for the works to be complete and then re-test at no extra charge. If it is not practical to carry out the remedial work on that day we will arrange for one of our air test engineers to attend site again on another day once the works are complete.

  1. Refer to the Communities and Local Government accredited construction details.

  2. Seal any gaps where pipes and cables pass through the building envelope.

  3. Seal any gaps around windows and doors.

  4. Ensure all mastic and corking has been applied.

  5. Drylining is notoriously susceptible to air leakage. Ensure that the plasterboard is continuous (i.e. there are no holes behind fitted units, sinks/baths, etc). When drylining directly on to an external wall the plasterboard should be mounted on ribbons of plaster or adhesive around all the edges rather than dabs. Ensure the joints between boards are sealed and the plasterboard is correctly detailed at joints, corners, reveals and window sills.

  6. Draught strip all windows and doors.

  7. Draught strip any loft hatches.

  8. Seal holes around light fittings and pull cords in the ceiling. If the light fitting is not airtight then install an airtight box over the light fitting in the ceiling void.

  9. Ensure there is a good seal around boiler flue pipes.

  10. Where metal cladding is installed ensure junctions between cladding are effectively sealed, and pay particular attention to junctions between metal cladding and masonry walls.

  11. Check to ensure there are no leakage points concealed within areas above suspended ceilings.

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