Domestic Air Pressure and Tightness Testing

ATTMA accredited Air Pressure certificates provided

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Air Pressure and Tightness Testing

House Air Pressure and Tightness Testing (Commonly referred to Air Leakage Testing or Air Pressure Testing) is a mandatory requirement for part L1A and L2A building regulations for all newly built houses (Commercial and Domestic).


An Air Pressure or Tightness Test is an energy audit that identifies any areas of unwanted air leakage in a building’s thermal envelope and should not take any longer than an hour to conduct.  The main reason for an Air pressure/Tightness Test is to create a more airtight building which in turn will reduce C02 emissions and lead to a reduction in heating costs and unwanted air leakage.  

All our house air pressure and air tightness test procedures are conducted in accordance to ATTMA (The Air Tightness Testing Measurement Association) standards and our aim is to improve the energy efficiency of your building at the most affordable market rates going. We provide  pressure testing throughout the UK. Whether you need a pressure test completing in Yorkshire, The Midlands, Greater Manchester or London we can complete testing at an affordable cost.

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Completing Air Pressure/Tightness Testing

Purple Energy have a dedicated team of engineers working throughout the country to provide accurate Air Pressure Testing and invaluable remedial advice, ensuring you achieve the air pressure results you require to pass part L building regulations.


The pressure test is a relatively simple and hassle-free experience if the appropriate guidelines are followed prior to our visit. One of our Air Pressure engineers will place a fan or number of fans to an appropriate opening. This is usually an external door. They will then proceed to take multiple readings at different air pressures.


Before the Air Pressure Test is completed we will tape all of the ventilation extracts, turn off any HVAC units and ensure all windows and doors have been closed.


If there are site works in the dwelling during the Air Pressure Testing process they must ensure windows are kept closed and doors are not tampered with. The Pressure/tightness test procedure should not take more than 45 minutes to complete, after which our engineer can provide you with an air pressure reading.  

1.) Arrival on site

Wind speed, air temperature and barometric pressures will be taken prior to testing. Quick check of building dimensions. 

Placing fan or fans on external opening (preferably an external door). Close all windows and external doors and tape ventilation terminals.

2.) Building preparation

2.) Building preparation

Take depressurised measurements from inside the building. Check for air leakage paths.  

3.) Depressurising

Results will be provided verbally to the client once the air pressure test has been completed. Certification will be issued within 24 hours of testing.   

4.) Certification

When do Air Pressure Tests fail

There are multiple recurring reasons why an air pressure test fails. These are the main culprits:


  • No sealing around skirting and windows

  • Lack of sealing around piping leaving the building

  • Incorrect installation of loft hatch

  • Down lights not installed

  • Holes in walls and ceiling


Should your air pressure/tightness test fail, rest assured one of engineers will be able to find where air leakage is occurring within the dwelling and provide the appropriate remedial work to help you achieve the result you are looking for.


Purple Energy have techniques available to identify where air leakage is occurring within a building. Some of these are:


  • Thermography - Is the process where an infrared camera is used to detect the difference in heat loss

  • Smoke test - Smoke pencils are placed in an area of leakage to identify any air flow.   

When is Air Pressure/Tightness Testing needed

We would recommend getting in touch with us as soon as possible to discuss the details of your air pressure test. This will ensure you achieve the score you are looking for, as one of our trained staff members can talk you through what is required prior to our visit.


Following the recommended guidelines below will provide the relevant information for a successful air pressure test:


  • All windows and doors must be fully installed

  • Gaps and holes must be sealed

  • 110v or 240v power needs to be available in the building

  • All soil pipes should be filled with water

  • Access to all rooms in the building is required

  • Any electrical sockets need to be installed


If there is anything you feel unclear about or you simply want to speak to one of our team members, don't hesitate to give our office a call.

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