A pressurisation test (also called a permeability test) is completed by installing a fan in the principal entrance doorway, sealing all fans, flues, chimneys, vents etc., and determining the air flow rate required to maintain an excess pressure of 50 Pascals (Pa) above outdoor air pressure. The pressurisation test must be completed in accordance with IS EN ISO 9972 by an individual or organisation competent to do so (NSAI or INAB accreditation for example). The test methods should be in line with the TGD L requirements:
The air permeability measured in this way, q50, expressed in cubic metres per hour per square metre of envelope area is divided by 20 for use in the DEAP software (to give an estimate of the air change rate per hour (ac/h) at typical pressure differences under real operating conditions). In this case, the structural infiltration entries of the ventilation: structural air tightness tab and building; windows/doors tabs (structure type, suspended wooden ground floor, draught-stripping of windows, doors, and attic hatches1) are not used. Section 1.5.4 of Building Regulations TGD L and provide further detail on air permeability pressure testing.
The result of a pressurisation test remains valid provided dwelling envelope changes (such as area changes, replacement of exposed elements, breaking of air barrier (for example inserting additional vents to the external) have not occurred since the test was performed.
Where the pressurisation test is not carried out, the ground floor must be specified as solid, suspended (unsealed) or suspended (sealed). A suspended wooden ground floor is considered sealed if all joints in the floor (at the edges and the floor itself) are draught sealed using membranes or adhesives.
In the case of a carpet on a suspended ground floor, while the carpet itself is unlikely to be airtight, a carpet underlay may or may not be airtight depending on whether it is proven to extend to the edges of the floor and the material in the underlay is airtight. When in doubt, it should be assumed that the suspended ground floor is unsealed. Air vents under the level of the suspended ground floor should not be included in ’intermittent fans and passive vents‘ in the ventilation: infiltration due to openings tab. The effect of these vents is already accounted for as part of the structural air tightness section. The suspended wooden ground floor entry does not apply to dwellings such as mid-floor or top floor apartments as these do not have a ground floor.
Relevant standards and minimum information required in air tightness test reports are detailed in TGD L Section 1.5.4. Also, as detailed in the DEAP Manual, the pressurisation test must be: “completed in accordance with IS EN 13829 by an individual or organisation competent to do so (NSAI or INAB accreditation for example)".
Note that the test standard IS EN 13829:2000 is now superseded by I.S. EN ISO 9972:2015. The list of NSAI accredited air tightness testers is here.
Air tightness test equipment calibration expiry
If the air tightness test certificate shows the calibration due date of the air tightness test equipment, and if that date was expired at the time the test was carried out then either:
A) A valid revised test must be provided, or
B) Written clarification from an NSAI (or equivalent) accredited air tightness tester must be obtained and held on file by the BER Assessor as to the acceptability of the original result.