Laundry Mould: Common Causes and How to Fix Them

Your laundry is supposed to make things clean — so why does it always seem to be the dirtiest room in the house when it comes to mould? Between the washing machine, dryer vents, wet clothing, and constant humidity, laundries are one of the highest-risk rooms for mould growth. If you’re fighting a losing battle against laundry mould, you’re probably missing the root cause.

Why Laundries Are High Risk

A single washing machine cycle can release 5-10 litres of moisture into the surrounding air through evaporation, steam from hot washes, and residual dampness on surfaces. If you’re drying clothes indoors on a rack, that adds another 2-5 litres of moisture per load. Multiply this by daily or near-daily laundry cycles, and the cumulative moisture load is enormous. When this happens in a small, enclosed room with poor ventilation, mould growth is almost inevitable.

Common Causes of Laundry Mould

• Inadequate exhaust ventilation: Many laundries have no exhaust fan, or have one that vents into the roof cavity instead of outside
• Indoor clothes drying: Drying clothes inside adds massive amounts of moisture to indoor air
• Washing machine issues: Front-loading machines trap moisture in door seals; residual water in drums supports mould growth
• Dryer vent leaks: Dryer exhaust ducting that’s disconnected, damaged, or venting into the roof cavity
• Plumbing leaks: Slow leaks from washing machine hoses, drain pipes, or sink connections
• Cold exterior walls: Laundries against exterior walls experience condensation in cooler months

Understanding the humidity and mould connection helps explain why controlling moisture is the single most important factor.

Fixing Laundry Mould

For existing mould on tiles, painted surfaces, and hard surfaces, clean with undiluted white vinegar using a scrub brush, then dry thoroughly. For mould on grout, apply a paste of baking soda and vinegar, let sit for 30 minutes, scrub, and rinse. For mould inside washing machines, run an empty hot cycle with 2 cups of white vinegar, then wipe the door seal and detergent drawer. For mould on walls, ceilings, or behind the machine, professional mould removal may be needed if the area is large or materials are damaged.

take our mould risk assessment to understand whether your situation requires professional attention.

Prevention Strategies

1. Install a proper exhaust fan that vents directly to the outside — this is the single most effective measure
2. Never dry clothes indoors without running the exhaust fan or a dehumidifier simultaneously
3. Leave the washing machine door open between loads to allow the drum to dry
4. Clean washing machine seals and detergent drawers monthly
5. Ensure dryer exhaust ducting is connected, sealed, and venting outside
6. Check all plumbing connections quarterly for slow leaks
7. Keep the laundry door open when not in use to allow air exchange with the rest of the house

If you’re also seeing mould in other rooms, check our guide on kitchen mould prevention for targeted prevention strategies across your entire home.