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Whilst considerable effort has been made over the years, UK dwellings, in their full life cycle from the manufacture of the materials through to its construction, eventual ownership and use, still produce a considerable amount of carbon gases.


Improving the quality of a dwelling's envelope in its construction, bearing in mind materials and workmanship, is a way of reducing this pollution together with the end users energy bills.  It also reduces the possibility of a cold, draughty dwellings and helps eliminate common building defects such as “cold bridging”.


Approved Document L of the Building Regulations for England, Wales & Northern Ireland and Section 6 of the Technical Handbook in Scotland requires provision to be made for the conservation of fuel and power and an acceptable level of air permeability within a structure.  The air leakage of a dwelling or structure can be demonstrated by testing through the application of an Air Tightness or Air Performance Test (APT).


Air pressure testing is generally required for all newly constructed dwellings including some extensions together with heated commercial buildings.


With regard to conversions, alterations, extensions, listed or other controlled buildings, and APT is not normally undertaken and an assumed result is provided.  However, it is still possible to test and a formal result can be provided.


In simple terms a temporary airtight screen is fitted into an external door (normally the front door) of the dwelling and the building is sealed.  This includes the filling of traps with water, closing trickle vents and sealing extract fans.  (Extract fan testing from bathroom, toilet and kitchen fans may be requested and is subject to a different testing regime but are normally required by the Warranty provider).


A fan is then mounted in the screen and operated to blow air into or out of the dwelling to create a pressure difference between inside and outside of approximately 50 Pa.


The air tightness of the dwelling is quantified by measuring the rate of airflow through the fan while a range of pressure differences between the inside and outside of the dwelling are maintained.


Common areas of failure are noted below:


  • around service penetrations (pipe work, etc) including those enclosed / boxed-in;

  • behind fitted units or behind bath and shower tray panels;

  • at the junctions of external walls and floors;

  • around windows and doors, generally at the junction of the frame and the recess or threshold

  • at socket points around electricity consumer units.


We have an established a network of Approved Inspectors who can facilitate Air Pressure Testing at the end of the build and they are also able to work with you and provide a comprehensive air tightness design service.


Should you have any queries, require any further information or would like a bespoke quotation, please contact us.

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