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Commercial developments:- Don’t let air test failures delay Practical Completion

Top 10 steps to reduce Airtightness test failures:


Air tightness testing is often viewed as a nuisance – but you need it for Building Control compliance and therefore for Practical Completion.

So why not get it tight first time and avoid potential delays and costs caused by failing air tightness tests.

Build Check work pro-actively with clients to help ensure the risk of failure is minimised – there are 10 steps you can take prior to testing to avoid additional cost and delays:


1.       Identify your Target Leakage rate specified in your SBEM (or SAP) calculation for the building. A target of 5m3/hr.m-2 or less means that a building must be both designed and constructed with Airtightness in mind

 2.       For low leakage rate buildings, Build Check provide on site Design Reviews undertaken with members of the Design and Construction teams. This is not expensive and helps ensure all parties give due consideration to air tightness.

 3.       Site inspections should be undertaken at key stages of the construction - including prior to installation of ceilings and say 1 month prior to the test.

4.       Large buildings often fail their first test via leakage through ductwork systems. Discuss effective sealing of these with M&E Contractor


Typical leakage paths include:

5.       Dry lining – air must not get behind dry lining. The interface between floor slab and soffit should be sealed around complete test evnvelope.

6.       Metal decking – profile fillers should be used around the perimeter of the test envelope. Seal joints/sheets.  Perforated decking – avoid if at all possible!

7.       Column casings – must not let air into wall cavity or behind dry lining.

8.       Membranes within walls are often leak during a test and thorough checking should be undertaken throughout the contract

9.       Services risers: check service penetrations and that door/access panels are air tight.  

10.     At interface between structural steelwork and the ATB / Dry lining – especially check hard to reach places


About Build Check

We are a team of highly skilled UKAS and ATTMA  accredited specialists, providing both on-site and laboratory based testing and certification services to the construction and fenestration industries. Our knowledge of the latest building regulations is unmatched. Having quickly and accurately evaluated your requirements we will provide you with honest, impartial advice on how you can achieve compliance.         

For further information on Building tests Click here

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