Air leakage pre-completion testing for all projects from small housing developments to mixed use schemes


Part L of the Building Regulations sets the energy efficiency standards for new homes and requires that a sample of new homes on all developments is tested for air leakage (also known as air tightness, air permeability or air pressure testing).

In partnership with BSRIA we offer a complete post-completion testing service in England and Wales. BSRIA are members of ATTMA and we have the experience to help you on any project with:

When do you need air leakage testing?

Testing should be carried out on completed properties. We recommend that you discuss your requirements with us at the design stage and book provisional testing date(s) at the same time so that they're incorporated into your build programme. However, as a minimum, you should book tests 6 to 8 weeks before you need to clear any relevant Building Control conditions.

What are the Part L requirements for testing?

The required rate of sample testing for Part L varies depending on the edition and is applied to groups of dwellings that are defined as similar based on specific criteria described within the Approved Document.

Part L 2006 sampling rate  
No. of dwellings in dwelling type group Sampling rate
1 to 4 1 test
5 to 40 2 tests
41+ Test 5% dwellings

If using Accredited Construction Details (ACDs) then 1 test of each dwelling type may be sufficient.

Part L 2010 and 2013 sampling rate

3 tests of each dwelling type or 50%, whichever is less.

NB. untested plots attract a penalty of 2.0 m3/(m2.h) in the final DER calculation (a.k.a. the 'as-built SAP').

Part L 2010 significantly increased the amount of air leakage testing required and also changed the way the results are used in the as-built DER/SAP assessments

Need more information on Part L 2010? Visit TechZone

Case Studies:

NHBC Air Leakage Testing Service is delivered in Partnership with BSRIA a UKAS accredited laboratory No. 1053, a member of ATTMA and an associate member of BINDT.


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