The Sunshine Coast doesn’t really get a dry season the way the inland parts of Queensland do. Even our cooler months bring overnight humidity high enough to keep mould happily multiplying in the wrong corners of the wrong houses. Late autumn and early winter are actually when we get the most mould-related call-outs, because owners notice it after they’ve cranked the air-con back and the airflow patterns in the house change.

A practical 2026 guide to keeping it under control.

What drives mould in coastal QLD homes

Three things, in order of importance.

Moisture. Mould needs moisture to grow. Coastal Queensland in 2026 has plenty. Ocean humidity, regular rain, condensation off cool windows in winter — all of it adds up.

Airflow. Without airflow, the moisture lingers in specific areas. Bathrooms after showers, laundries running dryers, kitchen windows after cooking, closets backed onto external walls. The lower the airflow, the higher the local humidity, and the better the conditions for mould.

Surface organics. Mould needs something to grow on. Painted plasterboard, untreated timber, the back of leather couches, fabric curtains pressed against walls — all of these provide the surface conditions mould needs to take hold.

You can’t really control coastal Queensland humidity at scale, but you can control airflow and surface organics, and those two are where the prevention work actually pays off.

What we see most often

The pattern of mould problems in Sunshine Coast homes in 2026 is consistent. The hot-spots are:

Ensuites and bathrooms with poor ventilation. Exhaust fans that vent into the roof cavity rather than to outside. Fans that don’t actually move much air. Fans that owners turn off the moment they leave the shower. The combination produces ideal mould conditions on the bathroom ceiling and along the wall-ceiling junction within 18 months.

Bedrooms with built-in robes on external walls. Cool external walls + closed robe doors + clothes that aren’t fully dry from the wash = a slow mould incubator on the back wall of the robe.

Laundries. Dryers vented into the laundry itself rather than to outside. Tubs without good extraction. The high humidity events from a dryer cycle can hit 90+ percent and stick around for hours.

Living room corners with limited airflow. Couches pushed against external walls, heavy curtains drawn shut for weeks at a time, lounges with limited cross-ventilation.

What actually prevents it

Run your exhaust fans for 15-20 minutes after showering, not 30 seconds. This is the single highest-leverage change most households can make. The moisture from a hot shower doesn’t dissipate in the time it takes you to towel off. Most modern bathroom exhaust fans use less power than a phone charger; running them properly costs almost nothing.

Get your roof cavity venting checked. If your bathroom exhaust vents into the roof cavity rather than to outside, you’re moving the moisture problem from one place to another. The mould you eventually find in the roof insulation is more expensive to fix than the bathroom mould would have been.

Open the windows when the weather lets you. Coastal Queensland has plenty of days in autumn and winter where the outside humidity is actually lower than inside humidity. Cross-ventilation for an hour or two on those days makes a real difference.

Don’t push furniture flat against external walls. Even 5cm of air gap behind a couch or wardrobe is enough to let the wall surface stay warm and dry. Furniture pressed against external walls creates a cold pocket where moisture condenses.

Watch your air-con condensate drains. Cracked or blocked condensate lines are a leading cause of mould in ceiling spaces near air-conditioning. The leak is often slow and hidden, and the first sign is a mould bloom on the ceiling below.

Cleaning what’s already there

If you’ve already got visible mould, the cleaning approach depends on how far it’s progressed.

Surface mould on tiles and grout. Standard mould-killing products work for this. Apply, let sit for the time on the label (not 30 seconds — most products need 5-10 minutes of contact time), scrub, rinse. The grout will usually need a follow-up treatment a week later to catch any spores you missed.

Mould on painted surfaces. More careful. The cleaning needs to remove the mould without destroying the paint. We typically use a diluted sugar-soap mix with a fungicidal additive, scrub gently, rinse, dry thoroughly. Heavily mould-affected paint sometimes needs to be removed and the surface repainted with a mould-inhibiting primer.

Mould in carpets. Hard to fix at the home level. Surface treatments give you a few weeks of relief but the mould typically returns if the underlying moisture issue isn’t fixed. The honest answer for severely mould-affected carpet is usually replacement combined with addressing the moisture source.

Mould in cavity walls or roof insulation. This is where the DIY answer stops. Professional remediation is genuinely warranted when mould is in the wall cavity or insulation. The cost is real but the alternative is recurrence and health issues for the occupants.

When to call us

Most home mould problems can be managed by attentive owners with the right approach. The situations where it’s worth calling in professional cleaning help:

After significant water damage events — a roof leak, a burst pipe, a flooded laundry. The mould risk in the 48-72 hours after a water event is the highest it’ll ever be, and professional drying and treatment in that window prevents most of the longer-term problems.

When you’re trying to sell or move out of a rental. Bond cleaning standards in Queensland include mould treatment, and what looks like minor mould to a current occupant often reads as a major issue to a property manager doing the bond inspection.

When mould is recurring despite your best DIY efforts. Recurrence usually means there’s a moisture source you haven’t identified, and a professional eye on the house often spots what’s been missed.

The honest reality of mould prevention in coastal Queensland is that it’s an ongoing maintenance discipline rather than a one-off solution. The households that stay on top of it spend a few minutes a week doing the right things and have few problems. The households that ignore it for months at a time pay for it eventually, usually at end-of-lease or sale time when the cost of fixing accumulated neglect is at its peak.