Which stains and problems are common on Sydney driveways?
Sydney's humid coastal climate and regular rain give algae and moss a good start on any surface that stays damp. South-facing drives and those under trees are the worst. Common problems include:
- Green and black algae on sloping or shaded concrete, which can also make the surface slippery.
- Tannin stains from fallen leaves, flowers and seed pods, including jacaranda and fig in many suburbs.
- Oil and brake fluid marks near the garage door or kerb.
- Rust spots from metal furniture, pots or sprinklers.
- White salt-like deposits, known as efflorescence, on newer concrete or pavers.
Why does the surface type matter?
Plain broom-finished concrete is the most forgiving. Exposed aggregate can lose small stones if the pressure is too high. Sandstone and some older pavers are soft and can be etched or pitted, so they need lower pressure and a wider tip. Sealed or stencilled concrete may need a gentler wash to avoid stripping the sealer.
