Mould is a form of Fungus and is spread primarily by airborne spores which will develop and grow on almost any surface, providing the following conditions are present:
- Relevant indoor humidity of 80% or higher.
- Moisture, usually from condensation. Mould can develop in the absence of condensation, but its growth is accelerated by the presence of moisture.
- A nutrient. Research has shown that certain ingredients in most paints and also household dust and cooking fumes provide excellent food for Mould.
Two types of mould are common: Sooty Mould, which leaves surfaces with a brown or black stain and which usually occurs on the walls and ceilings of bathrooms, bedrooms and in cupboards. Untreated, this mould will spread to other rooms in the house. Green Furry Mould which grows on organic or organic bearing surfaces such as shoes or clothes.
How to prevent mould
Mould growth is retarded by the circulation of dry air. It follows that proper ventilation will prevent most Mould growth. To prevent Green Flurry Mould on clothes and footwear, ensure that they are thoroughly dry before storage.
Methods to prevent condensation and mould
- Reduce indoor humidity by good ventilation and regular airing. Keep exhaust fans clear of fluff and do not block air vents.
- Dry indoor air with space heaters and wipe dry any surface on which condensation appears. Avoid the use of kerosene heaters; unflued gas heaters may also cause problems.
- Dry clothes and shoes thoroughly before storage.
- Allow sunlight into the home whenever possible.
- Remove any sign of mould growth on walls, ceilings and furniture using diluted household bleach or suitable household cleaner.
- Furniture should not be pushed up against walls. This creates dark airless areas and allows mould spores to grow.
Condensation and mould in houses and flats
The weather in all seasons can bring with it condensation and mould growth problems in houses, units, townhouses and villas. Condensation can occur in any type of home construction, including Weatherboard, Brick Veneer, Solid Brick, Masonry and Monocrete.
Condensation and its causes
Atmosphere heavily laden with water vapour is referred to as being of high humidity. When highly humidified air comes into contact with any cold surface such as a wall or a ceiling, it chills and water vapour is extracted from the air, remaining as condensation on the cold surface. This process can easily be seen if a cold bottle of cold water is taken from the refrigerator, wiped dry and left to stand in humidity. Condensation forms quite quickly on the surface in the form of droplets. High humidity has accumulative effect on absorbent materials such as clothing hanging in the cupboard, or bed clothes, making them damp. Condensation will cause rust on metal surfaces such as spring wire mattresses.
How to prevent condensation
Condensation cannot occur if humid moist air is removed and replaced by dry air. Scientific investigation and practical experiments have shown that this can be achieved very simply by better ventilation of dwellings.
Some ways of improving ventilation are:
- Open windows and doors whenever possible. Where window locks are provided- lock windows open 10cm while not at home.
- On cold nights, when the house or flat is closed against cold, ventilation should be ensured during the day.
- If the dwelling is closed during the day, windows and inside doors should be open during the night, particularly in space where heaters are operating.
- Exhaust fans should be kept clean. Normal house fluff can block or partly block wall or ceiling ventilators and thus impede proper ventilation.
Warm air will not cause condensation on a cold surface, but moist air will. Some problems caused by warm moist air are created by:
- Kerosene and Gas room heaters
- Steam from cooking
- Washing dishes or clothes
- Clothes dryers which are not externally ventilated
- Steam from bathroom
- Drying damp clothes inside