Air Tightness Testing
Air Tightness Testing is also known as air permeability test, air leakage testing or air changes per hour.
The test measures the amount of uncontrolled conditioned air escaping from the interior of a building through gaps, holes and cracks.
Why do I need an Air Tightness Test?
Building Regulations (Part L) for domestic & commercial new builds or conversions require that the building meets or exceeds certain air permeability rates specified in the design stage SAP calculations. The method is to carry out an Air Tightness Test. Tests are carried out in accordance with ATTMA TSL1 & TSL4 standards.
Part L - Click here
ATTMA TSL1 standards - Click here
ATTMA TSL4 standards - Click here
What do I recieve at the end of the test?
Once the test is finished you will be provided with a certificate showing the results. This certificate will be lodged with ATTMA and if compliant will also satisfy the conditions of the Building Regulations part L. Passiv homes or low energy properties will also receive 3D modelled drawings and calculations for their files.
When Should an Air Tightness Test be carried out?
Usually you should carry out Air Tightness Testing towards the end of your project unless its a Passiv house or you have specified otherwise.
Tips for achieving Airtightness;
Click here for ATTMA guidance to help you determine when your building is ready.
Temporary sealing;
Click here for ATTMA guidance to determine what is/is not allowed to be sealed.
What are the benefits of Air Tightness Testing?
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Compliance with current Building Regulations.
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Impacts the buildings EPC rating.
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Reduced heat Loss & energy usage.
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Lower heating bills.
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Lowers C02 emissions.
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Stems the spread of fire.
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Thermal comfort due to consistent indoor temperatures.
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Prevents interstitial condensation reducing the risk of mould growth and structural damage.
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Improved, healthier indoor air quality as controlled air ventilation systems will manage pollutants and allergies.
How is the the test carried out?
Prior to us attending site we calculate the envelope of the building in m2 and the volume of the building in m3 (if Passiv/low energy) from the plans you have supplied using 3D modelling.
During the onsite test we will place a large UKAS calibrated fan in an expandable frame into the main external door of the building. The other external doors and windows remain closed with internal doors open. The fan will pressurise/depressurise the building whist our UKAS calibrated manometer reads the internal pressure, the external pressure and the strength the fan is having to work to create that pressure difference. A number of readings are taken with other factors such as barometric pressure and temperature which then allows air permeability to be calculated.
Whilst we are conducting your test, other contractors can continue work within the property. However, all windows and doors must remain closed for the duration of the test.
How long does the test take?
Once we have worked out your buildings envelope area/volume off site, The actual duration of the test will depend on the building size and the level of preparation undertaken before testing. Generally the duration of the actual test should take no longer than two hours.
What happens if My building fails the Airtightness Test?
If your building does fail, we offer a number of services to ensure that the process is ultimately a success. We will give you full feedback and suggestions to help you make changes which will ensure a pass during the second test. The retest can usually be completed on the same day if the reason for non compliance is fixed within 1 hour.