Condensation & Mould Condensation arises because warm air can hold more moisture than cold air. For example air at 25 degrees C can hold about 20 grams of water per kilogram of air. This is its maximum water content so it corresponds to 100% humidity. If air in this state is cooled to 15 deg C then its maximum water content falls to about half this value and about 10 grams of water must condense out of each kilogram of air. This will occur as a fog of liquid droplets if the air is cooled as mass or as condensation of a surface if that surface provides local cooling of the air around it. The presence of condensation will be reduced in direct proportion to the increased temperature of the internal walls. Condensation has settled on the walls and windows of the subject unit, forming the basis for mould growth. Mould growth is evident in the unit in all rooms except the kitchen and hallway. The mould is particularly evident behind furniture and the like where there is insufficient cross flow ventilation present to disperse the natural exhalation being generated by the occupants. Typical quantities of water vapour produced in the home are (in litres per hour): Adult breathing 0.1, Hot bath 1.5, Washing machine 3.0, Clothes drier 5.0 and Shower 10.0. Many domestic and industrial appliances such as gas; oil and kerosene fired stoves, burners and heaters produce large quantities of water as a product of combustion. This problem does not arise with flued appliances. The dilution of moisture bearing air in the unit will also assist to reduce condensation. Normally this process is achieved through high wall vents, which continually encourage cool outside air to displace warm moisture laden air at the ceiling level.   Typical factors contributing to condensation problems in properties: Design characteristics of the home/unit: The structure has a closed design layout where individual rooms are isolated from each other; There may be damp conditions existing under the floor due to the presence of environmental damp such as excessive ground water of a persistent plumbing problem; Sub-floor ventilation may be inadequate; The high wall vents may be blocked or obsecured or non-existent; The problem rooms are located away from the warming rays of the northern sun; The heating provisions are inadequate or being used locally only. Living habits: Condensation settles on walls where normal household traffic activities are minimal. The dwelling is locked and left idle during the day; Mould may be particularly evident behind furniture, curtains and the like where there is insufficient cross flow ventilation being generated to disperse the prevailing humidity and the natural exhalation being generated by the occupants; The exhaust fans in the high humidity areas such as the bathroom or the kitchen may be inadequate or not being used appropriately.   Possible Rectification Options: High wall vent replacement internally and externally. Consider extended use of the kitchen, laundry and bathroom exhaust fans. If the exhaust fans vent to ceiling consider reventing to outside. If the internal heating is ineffective a heating specialist should be engaged to advise which heating system should be installed to generate even heat throughout the unit and effectively raise the dew point of the walls. The existing mould can be removed with standard houshold bleach or anti mould agent and the damaged paintwork replaced with an anti mould repainting specification. Installation of an anti-condensation unit located in the ceiling space and recirculating warm filtered air from the ceiling. For specialist advice, a sub-floor inspection can be arranged with our office which will give a full report on these issues. For further information on Condensation & Mould please call (03) 9885 9444 or send an email to enquiries@fgjames.com.au