Home and Building, Volume 37 Number 6 (1975)
Forty-six per cent of New Zealand homes have mildew, according to a recent survey made by the Building Research Association of New Zealand. One home in five has repeated or prolonged attacks and one home in seven has condensation leading to damp wall linings.
BRANZ also reports that mildew can occur in any type of construction and is common in both mild and severe climates. It occurs on shoes and clothes in the wardrobes, on wallpaper, curtains and ceilings.
Condensation is also widespread, but appears to be heavier in colder climates. It occurs on windows, especially metal framed ones, on walls and ceiling linings. Condensation can leave water stains, help rot to set in and can cause mildew growth.
BRANZ advocates making sure there is some ventilation in all rooms at all times. The Association says many windows slightly open are better than one window fully open. If windows start steaming up, open them wider.
Short bursts of vigorous ventilation don't help much except when flushing out moist air, such as after a bath or shower. Indoor temperature should be at least 5°C warmer than outside all the time. A little heating usually uses less energy overall than a lot of heating in the evening only.
Both insulation and heating through-out the home will help to lessen the chances of mildew and condensation but will not prevent them, BRANZ says.