How to Remove Mould From Outdoor Concrete

If you've got green or black patches spreading across your concrete driveway, patio or paths, you're dealing with mould and algae. It's incredibly common in Wollongong and the Illawarra — the coastal climate provides the perfect conditions for organic growth to thrive on outdoor surfaces. Professional pressure cleaning in Wollongong removes it safely and properly.

Left untreated, mould and algae don't just look bad. They trap moisture against the concrete, making the surface slippery and potentially accelerating wear. Here's how to deal with the problem properly.

Why Mould Grows on Concrete

Concrete is porous. That means it absorbs moisture, and moisture combined with shade and organic matter (like leaves and dirt) creates the ideal environment for mould and algae to colonise. South-facing surfaces, areas under trees, and sections of driveway that stay damp are the usual suspects.

In coastal areas like Wollongong and Shellharbour, salt spray adds another layer — it leaves a residue that organic growth can cling to more easily.

Can You Remove Mould Yourself?

For light growth, a bleach solution and a stiff broom can provide a temporary fix. But there are real limitations:

• Bleach kills surface growth but often leaves the root structure intact, so mould returns within months
• Domestic pressure washers lack the power to remove deeply embedded growth
• Improper pressure washing can etch or damage the concrete surface
• Run-off from chemical cleaners can damage surrounding gardens and lawns

The Professional Approach

Professional mould and algae removal combines the right pressure with appropriate treatment solutions to kill the growth at the root and remove it from the surface. This means:

1. Assessing the surface — not all concrete can handle the same pressure
2. Applying a targeted treatment to kill mould and algae at the source
3. Cleaning with appropriate pressure to remove growth without damaging the concrete
4. Rinsing thoroughly to remove all residue and spores

This approach doesn't just clean — it treats the cause, meaning the surface stays cleaner for much longer.

Preventing Mould From Coming Back

Once your concrete is properly cleaned, a few steps help slow regrowth:

• Trim back overhanging branches to increase sunlight and airflow
• Keep the surface clear of leaves and organic debris
• Consider sealing the concrete — a quality sealer reduces porosity, making it harder for mould to take hold
• Schedule regular concrete cleaning to catch growth early

If mould and algae are taking over your outdoor concrete or pavers, ClearView Exterior Services can help across Wollongong and the Illawarra — including Shellharbour, Thirroul and Kiama. Request a free quote or call 0403 507 558.