Why Queensland roofs get dirty so fast
Warm, humid weather is exactly what algae, mould and lichen need. Near the coast, salt air and sea breezes keep surfaces damp for longer. Up the range, cooler, misty winters do the same job. Either way, roofs here grow things faster than in drier parts of the country.
Most of that black streaking isn’t dirt at all. It’s algae feeding on the roof surface, and it spreads a little further every year.
What makes your roof need cleaning sooner
Shade: overhanging trees keep a roof damp and drop leaf litter that feeds growth.
Direction: south-facing roof sections get the least sun and usually go black first.
Location: bayside suburbs and misty range towns both grow mould quickly.
Roof type: textured concrete tiles hold moisture and growth more than smooth metal.
Signs it’s time
Don’t go by the calendar — go by what you can see from the ground. Black or dark streaks running down the roof, crusty grey or orange spots of lichen, green moss in the valleys, or gutters filling faster than usual are all good signs a clean is due.
How to make a clean last
The biggest difference is how the roof is cleaned. Pressure cleaning blasts growth off the surface, but the roots survive and it grows back quickly. It can also crack tiles and strip coatings. A soft wash kills the growth at the root, so the roof stays clean far longer.
Between cleans, trimming back overhanging branches and keeping gutters clear both help. And please stay off the roof — it’s slippery and it’s not worth the risk.