Mildew
Condensation and mildew are mainly winter problems and each year the Council receives many inquiries and complaints relating to condensation and/or mildew growth on walls and ceilings.
Condensation
All air contains water vapour, but can only hold only a limited amount without becoming saturated. The higher the temperature, the more it can hold. If there is too much moisture in the air for the temperature, then some will condense on the cold surfaces in the house. Condensation is widespread but appears to be heavier in colder climates.
It can be caused by construction faults but more commonly is caused by moisture generated by activities such as cooking, showering or failure to ventilate. It also occurs on windows, especially metal framed ones, and on walls and ceiling linings. Condensation can leave water stains, help rot to set in and can cause subsequent mildew growth.
Mildew
Mildew is a primitive form of plant life. It grows from spores that abound everywhere. It will grow in any home where humidity remains high, but will have difficulty surviving in a house with low humidity. Growth occurs when the atmosphere within a dwelling remains damp and when little ventilation is provided.
It can occur in any type of construction, is common in both mild and severe climates and it is often found on shoes and clothes in wardrobes, on wallpaper, curtains and ceilings.
More information
For more information or advice visit the BRANZ website, the Department of Building and Housing website, or contact the Council's Environmental Health Division: phone 211 1777.