Air Permeability & Pressure Testing - Temporary Sealing Guidance


This guide has been created to advise builders, developers, architects and building authorities about what in fact a temporary air is. It also details what is not acceptable when carrying out testing in accordance with the technical guidelines and set out by the Approved Document L1A.

What is an acceptable temporary seal?

All the temporary seals listed below should be carried out internally and it recommended that these works are done in advance and prepared ready for the test.

Mechanical Ventilation (Extractors, MVHR, Air Handling)

Mechanical ventilation systems such as wetrooms and kitchen cooker hoods must be switched off before being temporarily sealed for the test.

Trickle Vents

Trickle vents shall be closed and can be temporarily sealed. It is common practice for temporary sealing not to take place with trickle vents only being closed. Weather closed or sealed, closed trickle vents have minimal impact on the overall air permeability.

Air Conditioning

Air conditioning grills can be sealed internally. It is important to check and confirm that the air conditioning is switched off during the test.

Passive Ventilation

Passive Ventilation, such as air bricks to outside (hit & miss vents) should be temporarily sealed for the test. Ventilation grills (leading into boiler cupboards, for example) should not be sealed.

Chimney Flues

Chimney flues can be temporarily sealed for the test as these items are accounted for in the SAP calculation methodology. It is recommended that a chimney balloon is used.

Door Template

There may be occasions where the door fan equipment does not fit cleanly into the doorframe. It is acceptable to temporarily seal around the doorframe to ensure there is no leakage through the set up area.