Minimising Condensation in Buildings

This video provides an overview on the effects of condensation within buildings, as well as 10 key tips for reducing water vapour levels indoors due to regular occupant activities.


Australian Building Codes Board

Why is condensation a problem?

Persistent condensation can damage building contents, framing members, internal linings, external cladding, insulation materials.

High humidity in homes can trigger mildew and mould growth providing perfect conditions for dust mites.

Mildew, mould & mites can be detrimental to your health!

So what increases condensation?

Factors include: temperature and humidity, terrain, soil moisture, building form, exposure to weather, construction methods & materials, people & their behaviour in buildings.

Did you know?

Our habits and choices can increase indoor humidity.

Each adult contributes to approximately 3 litres of water vapour per day! Simply through breathing & perspiring.

This makes people one of the largest direct sources of unwanted indoor water vapour.

What can we do about it?

Apart from spending more time outdoors, there is little that can be done to avoid this.

10 key tips for reducing water vapour indoors.

1. Common sources of water vapour

Ensure that water vapour from these sources are ducted directly to the outside: showering, cooking, drying.

2. Cooking: range hoods

Do not depend on circulating range hoods to remove water vapour. Air is simply filtered for odours and grease and returned to the room.

A ducted range hood can collect and remove water vapour from cooking to the outside.

3. Cooking: stove tops

Place lids on saucepans while cooking and turn the heat down accordingly.

4. Natural ventilation

Open windows: in the bathroom after showering, in the kitchen while cooking, in the laundry while soaking, washing or drying clothes, and in other rooms when the weather permits and outdoor humidity is low.

5. Drying clothes

When using a tumble dryer that is not of the condensing type, ensure that: the air outlet is ducted outdoors, the ventilation duct is not leaking, and the duct discharges clear of any window or eave ventilation opening. \

If you are unable to dry washing outside or in a ducted dryer, choose a room that can be: heated, ventilated, and shut off from the rest of the building.

6. Lighting

Avoid light fittings that allow warm, moist air into a colder roof space. This increases the risk of condensation.

7. Heating

Do not store large quantities of firewood indoors unless there is adequate ventilation.

Avoid the use of unflued gas heaters. They can produce up to 5 litres of water vapour during a single evening!

8. Spas and Saunas

When installing a spa bath or sauna, ensure provisions are made to remove the high levels of water vapour.

9. Aquariums

Keep lids on fish tanks to prevent the formation of water vapour.

10. Plants and Water Features

Avoid introducing indoor plants or water features to rooms with limited ventilation.

Do you want more information on condensation prevention? This can be found in ABCB’s Condensation in Buildings Handbook.

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