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How to quantify the need for subfloor ventilation

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Envirofan  specialise in subfloor ventilation, underfloor ventilation and roof ventilation consulting. When attempting to quantify the need for subfloor ventilation, there are three aspects to look at:


The picture above is an example of a severe subfloor ventilation problem which has been engulfed by mould and dry rot. The flooring material has expanded due to excessive moisture. In this case not only would a subfloor ventilation consultant be engaged, but also the services of a carpenter would be needed to replace the damaged floor.

Condensation as water droplets on timber and suspended concrete floors would be another indicator of  inadequate subfloor ventilation. As the consumer the first point of reference to look for with regard to subfloor ventilation requirements is to conduct a ‘visual inspection’  


Secondly in normal circumstances whilst walking on the floor it should not ‘bounce’. This occurs when joists and bearers under the building have absorbed moisture above its ambient moisture content. When this occurs these timbers expand and lift off the brick piers thus becoming slightly convexed. When effective subfloor ventilation is administered this should diffuse the pressure build up in the subfloor area by the extraction process, getting cross-flow ventilation on track. There are other causes why floors ‘bounce’ so a holistic approach must be taken into consideration.  

Musty Smell  

The presence of a ‘musty smell’ would also be apparent. This occurs when humidity and organic material in the subfloor area interact in releasing an odour which penetrates through the flooring materials whether tongue and groove or chipboard flooring. To our respiratory system, this is not healthy. It is best to rid the home of this smell by extracting it from the subfloor area by means of effective subfloor ventilation.

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