Part L Building Regulations 2000, which came into effect on 6th April 2006, is one part of the Governments procedure to reduce the Carbon footprint of the UK. Within the Part L documents, requirements are placed upon new buildings to meet specific air permeability targets (10m3/h.m2 @ 50 Pa).

Whilst this requirement has been in place for a number of months at the point of publication of this article, it is the author's experience that on the whole the process of air tightness testing is still lacking in its understanding and importance by many in the building trade.

Air testing is no longer a nicety but an important implication to the building trade, and where contractors have not considered the implications of the air barrier, or worse where architects unaware of the new building regulations and design a structure that is complicated or in the worst case impossible to seal correctly in specific locations, the result can be unnecessarily costly to correct.

On the opposite side of the coin however, a number of companies realise the relevance of air testing, and the cost associated with attempting to remediate a failed test after construction has been completed.

This is where the key issues lies. Contractors, and Architect realising the implications of the air tightness testing and attempting at the point of design and build, to ensure that where practically possible measures are taken to correctly consider the design more carefully, and during construction, ensure that contractors are aware of the issues and take more care in their constriction methods.

A simple example that I have often encountered on site involves plumbers and electricians. As they start work and place cables and piping through the air barrier, (such as the cavity wall) they often create much larger openings than are necessary. This then adds the problem where these openings are not correctly sealed when work is completed, or in some cases not even sealed at all, and become hidden by internal panels, etc.

There is often the miss conception that air will be stopped by such barriers and the sealing of such openings is time consuming and unnecessary. Whilst air is in some way stopped by such barriers, it is by no means very effective. This is why it is imperative that such work is completed to a high standard, and checked regularly by the site manger to ensure that contractors are completing work as instructed. A single small location badly sealed on a large building will have minimal effect, but numerous breaks in the air barrier will.

But what are the implications of failing the air test? In some sectors of the building trade there is a miss connection that the fail is, whilst not good, is not important. They are unaware that without a pass, building control should not approve the completed building. The implications being, you are unable to hand over your building, or complete a sale.

However, often contractors are unsure about the process that can lead to a failure in an air test. The solution is simple, if you have no experience and are unsure; seek the advice of a professional ATTMA accredited company. Experience comes from practical application, and learning this through a costly failure of a project is not an effective method, and a problem I have encountered on a number of projects. It cost nothing to inquire through the various approved testing companies listed at the ATTMA website, but it can cost thousands in improvements and repeat testing.

To summaries the lessons are simple.. design appropriately and consider the air barrier, ensure construction is effective, and where unsure seek the advice of accredited professionals.

Steven Marriott
Test Engineer - STROMA Technologies