Damp and Mould Guide for Australian Homeowners

Health Impacts of Mould

Mould produces mycotoxins and spores that trigger respiratory issues, allergies, and in vulnerable people (children, elderly, immunocompromised), serious health effects. Black mould (Stachybotrys) is particularly problematic. If household members experience unusual respiratory symptoms, mould may be a contributing factor.

Finding the Source of Moisture

Mould needs moisture to grow. Before treating mould, identify and fix the moisture source. Common causes in Australian homes: roof leaks (check ceiling after rain), plumbing leaks (check under sinks, behind washing machines), condensation (common in cool climates with poor ventilation), rising damp (affects older homes with no damp course), and inadequate sub-floor ventilation.

DIY Treatment for Minor Mould

For surface mould on paint (small area, less than 1m²) with no penetration into the substrate: clean with a diluted solution of bleach and water (1:10 ratio) or commercial mould killer. Wear gloves, eye protection, and a P2 respirator mask. Ventilate the area well. Treat, allow to dry, then repaint with anti-mould paint.

When to Call a Professional

For mould areas larger than 1m², any black/dark mould, mould in roof cavities or sub-floor areas, or mould that returns quickly after treatment — engage a licensed mould remediation specialist. They will test the mould type, contain the affected area, safely remove contaminated materials, treat structural elements, and provide an air quality clearance test after remediation.

Prevention in Australian Homes

• 1 Run exhaust fans in bathrooms and kitchens for 15 minutes after use
• 2 Install a whole-house heat recovery ventilation (HRV) system in cool, humid climates
• 3 Ensure sub-floor is well-ventilated — add sub-floor ventilation fans if condensation is visible on floor joists
• 4 Set split system to dehumidify mode during humid weather
• 5 Maintain indoor humidity at 40-60% — buy a hygrometer to monitor