Air Pressure Testing/ Air Tightness Testing


Also known as Blower door testing, Pressurisation testing and Air Permeability testing the Air Pressure Test became mandatory to all new dwellings as and from the 1st of July 2008.


An Air Pressure Test is carried out using a Blower door device, and once set-up the blower door device measures the air tightness of your dwelling and also helps to find the location of air leaks through the building fabric (gaps/cracks in the external walls, roofs, floors etc.).


The Test


The Blower door fan is temporarily fitted into the external door of your dwelling, and the associated equipment is set-up around this.  All remaining external doors and windows are shut.  All internal doors are secured in an open position to ensure free flow of air inside the dwelling.  All chimneys, flues and ventilation openings are temporarily sealed.  All combustion devices such as your heating system and gas water heaters etc. are switched off as the blower fan functions in de-pressurising your dwelling.


Once all preparations are complete the blower fan is switched on and functions in pulling the air out of the house (de-pressurising) thereby lowering the air pressure inside the dwelling.  The higher outside air pressure then flows in through all the unsealed cracks and openings, determining the air infiltration.  At this stage the auditors may use smoke pencils to detect the air leaks for you.

The speed of the fan is adjusted in order for multiple measurements to be taken and recorded over a wide range of pressures. These results are then averaged using specialist software to give an accurate result.




In order to comply with the Building Regulations TGD Part L 2011 a performance level of 7m3/(h.m2) represents a reasonable upper limit for air permeability.

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