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If you think Australia is immune from condensation and sick building syndrome, then it is worth your time to read a report from the CSIRO which raised these exact same concerns and was published as far back as 2001 - long before recent increases in bulk fibre insulation levels.

“Higher levels of insulation may introduce unforeseen problems where they are incorporated into construction styles which have previously been relatively immune to condensation. This is because insulation, while it keeps some surfaces warm, also keeps other surfaces cold.”

“A simple example is domestic roof spaces. High levels of ceiling insulation means that roof spaces are colder, as they are not heated to the same extent from below.”

A generation of buildings in other temperate climates in Europe, North America, Japan and New Zealand have  been through a cycle of moisture related problems closely correlated to changes in construction methods to improve energy efficiency. The failure to consider the building envelope holistically created problems by trapping moisture within the structure.

A quick search on the internet on sick building syndrome, leaky homes or mouldy homes, reveals an embarrassing history of how the building industry has failed to learn from the mistakes made elsewhere.

Australia has a broad range of climates ranging from tropical to desert to alpine. Each of these climates presents an unique set of condensation issues. The good news is there are well researched and proven solutions that have been adopted successfully both here and overseas. If you are aware of the potential for problems, expensive rectification can easily be avoided at the design stage for a fraction of the cost of fixing a problem once the building is occupied.

Who is responsible when it all goes horribly wrong?

Common practice does not always mean best practice. Doing what was done 20 years ago and hoping that “she’ll be right” is being overly-optimistic. The buildings of today are simply not the buildings of 20 years ago.

It is common practice in the cold and temperate climates of Australia for buildings to have a layer of foil type sarking installed under the roof and/or behind the external wall cladding. Foil type sarkings used for their properties as radiant barriers have been maintained above dew point due to the lack of insulation.

However, the drive for a more energy efficient built
environment is leading to improved air tightness and the installation of more bulk insulation in the walls and roof space. Unfortunately this practice has a damaging knock on effect as the surface temperature of foil sarking vapour barriers falls below dew point, causing interstitial
condensation to form - as shown on the images opposite.

Nevertheless, contrary to warnings contained within the BCA and the basic rule of building physics - foil type sarkings continue to be installed behind the external wall claddings, brick veneer or under roof tiles in cold and temperate climates, often with ruinous results.  
                
So who will be held responsible when it all goes wrong?

It is the building designers responsibility to consider condensation risk as part of the design and to ensure that the materials are correctly specified and installed so that they do not cause condensation problems.

It is worth clarifying whether the architect or builder is taking responsibility for condensation risk and who will rectify any future problems. If the responsibility for design falls to you, seek strong assurances that your sarking is breathable enough to prevent condensation when used in combination with the insulation specified, and in the climate where you are building.

Condensation Risk Analysis Service 
Dynamic Composite Technologies offer a free condensation risk analysis service available through the Technical Advisory Service of our website.

Alternatively please send us the following information by email: info@dctech.com.au

• a basic cross section detail of the proposed wall/roof
• the thickness and type of insulation and other materials proposed
• details of construction types and proposed building use
• location of the project

Dynamic Composite Technologies use independent software, Australian climate data from the Bureau of Meteorology plus our database of common material properties to conduct a condensation risk analysis.