Air Tightness Testing Requirements

Air tightness testing is a means to quantify the extent to which buildings 'leak' air through their envelopes (for example perimeter walls, roof and floor slab). Air leakage (also referred to as air infiltration) is a vehicle for energy wastage, resulting from the increased loads placed on the space heating and/or cooling systems by the constant uncontrolled flow of air through the building fabric.

Regulations

Building Regulations for England & Wales, through the Approved Document Part L ('Conservation of Heat & Power'), stipulate the air tightness testing of buildings. Currently, this requirement exists in three of the four Part L Approved Documents:
  • Part L1A: (applicable to new dwellings); and
  • Part L2A: (applicable to new non-dwellings)
  • Part L2B: (applicable to large extensions to non-dwellings) 
REVISED VERSIONS OF THESE APPROVED DOCUMENTS WERE INTRODUCED IN OCTOBER 2010, WHICH WILL HAVE A SIGNIFICANT IMPACT ON REQUIREMENTS FOR THE NUMBER OF AIR TESTS AND PERFORMANCE LEVELS.
PLEASE REFER TO THE DOWNLOADS ON THE RIGHT FOR MORE INFORMATION ON THE IMPACT OF THESE REVISIONS.
Revised ADL (from Planning Portal)


Competent Testers

Air tightness tests have to be conducted by 'competent persons', as clearly stated in the Building Regulation itself (Regulation 20B), and the supporting Approved Document Parts L1A and L2A:
"An approved inspector is authorised to accept, as evidence that the requirements…have been satisfied, a certificate to that effect by a person who is registered by The British Institute of Non-Destructive Testing in respect of pressure testing for the air tightness of buildings." (Building Regulation 20B)

In short, the only way for an air tightness tester to demonstrate competence for the purpose of conducting air tightness tests for Building Regulations purposes is to be registered (certified) by BINDT.

Reflecting the fact that the technical challenges posed by the air tightness testing of 'Dwellings' for Part L1A are generally more straightforward than those potentially posed by 'Non-Dwellings' for Part L2A, BINDT operates two registration schemes:
  1. The BINDT L1A Dwelling Air Tightness Tester Scheme
    The L1A Scheme has individual members who have been certified by BINDT as competent to conduct air tightness tests of dwellings, as required by Building Regulations Approved Document Part L1A.
  2. Membership of the ATTMA (Air Tightness Testing & Measurement Association)
    Membership of ATTMA is at an organisational level. Member organisations have to be UKAS-accredited air tightness testing laboratories, and have passed an ATTMA Technical Interview. Member companies are consequently certified by BINDT to conduct air tightness tests on any building type (ie both residential and non-residential). Their employed testing staff can therefore be deemed qualified to conduct the tests required under both Parts L1A and L2A.

For the testing of any building type: ATTMA Members

The ATTMA (Air Tightness Testing & Measurement Association) was formed in 2002 by leading air tightness testing organisations at the request of the Government, who have since relied upon ATTMA for the provision and regular updating of the definitive air tightness testing methodology (ATTMA TSL1 and ATTMA TSL2) that should be adhered to for all Building Regulations air tightness tests.

All ATTMA members are experienced testing organisations that are UKAS-accredited for air tightness testing and have successfully undergone initial vetting by the ATTMA Technical Committee.  

By virtue of their adherance to the requirements of BS EN ISO 17025 and BS EN 13829 (as confirmed by their UKAS accreditation), they operate internal employee training and competence systems that ensure that their testing staff are deemed competent, both by UKAS and BINDT.

Consequently, ATTMA member organisations and their employed testing staff are registered and certified by BINDT to conduct air tightness tests on any type of building.

List of ATTMA members


For the testing of dwellings: The BINDT L1A Dwelling Air Testers

Members of this scheme are individuals that have successfully undergone a BINDT-approved training course, examination and test appraisal regime. To summarise, each certified L1A Air Tester:
  • Has successfully completed an approved training course.
  • Has passed both theory and practical examinations.
  • Is covered by professional indemnity insurance.
  • Uses properly calibrated equipment.
  • Is working in accordance with an approved Quality System.
Where certified individuals are employed by a testing company, the company itself is not certified under this scheme, but they are obliged to conform with the scheme requirements and codes of conduct.

Note: Members of the BINDT L1A Dwelling Air Tester Scheme are not certified to test non-dwellings, as this would be to operate beyond the scope of their proven competence. Any L1 scheme members undertaking non-dwelling tests are in breach of the associated BINDT Code of Conduct, and risk loss of BINDT certification.

Refer to the links on the right hand side of this page to download a list of the current BINDT L1A registered testers.