An ATTMA member has written a brilliant article on condensation management. The article focuses on ventilation and moisture control to avoid condensation problems.
The article touches on the difference between ventilation and air leakage. Ventilation is a system for removing and replacing air which includes exhaust fans, ducts, vents, doors and openable windows.
Air Leakage is the result of building imperfections or the gaps in the buildings envelopes. Ventilation systems are designed so they are planned to create air movement in the home whereas air leaks are the opposite, as they are unplanned and deviate from the designed air flow. Air leaks in the envelope of the home are responsible for the majority of moisture that makes it ways into spaces.
“Build tight and ventilate right”
The article mentions the expression ‘Build tight and ventilate right’. An advocate for Passive House building standards was quoted in Sanctuary magazine saying, “either go full certified Passive House or build a standard house, don’t go in between the two”. This was demonstrated in Kinglake, Victoria, where one home was rebuilt with an airtight vapour impermeable foil and within months, structural damage occurred due to condensation.
Whilst the above is an extreme example of what could happen, it is thought to be happening to many homes gradually in the walls and roofs of many cooler climate Australian homes. This is due to the impermeable foil which makes the house ‘unable to breath’. The internal envelopes of new homes are also still extremely leaky, and this combined with the external envelope being impermeable, makes matters worse as warm air which carries water vapour is trapped.
The article comments that a solution to this problem could be plasterboard as it is vapour impermeable and moisture travels very slowly through it, compared to air leaks.
In summary, in order to protect your home from condensation and potentially damaging structural damage, correct ventilation needs to be used in homes and not through gaps in the envelope
For the article in full – https://renew.org.au/renew-magazine/efficient-homes/condensation-management/