The short answer: about once a year
For most Auckland homes, a soft wash once every 12 months keeps mould, algae and lichen from taking hold. Our climate is warm and wet for much of the year, which is exactly what these organisms love — so build-up happens faster here than in drier parts of the country.
A yearly wash is usually enough to keep your cladding looking fresh, protect your paintwork, and stop grime becoming stubborn and harder (more expensive) to remove later.
When you might need it more often
Some homes green up faster than others. If your place is shaded, surrounded by bush, north-facing walls that stay damp, or close to the coast, you may notice mould returning within six to nine months. South-facing walls that get little sun are the usual first offenders.
If you can already see green or black patches, dark streaks under the gutter line, or a chalky film on the cladding, that’s your cue — it’s ready for a wash regardless of when the last one was.
Why regular washing saves money
Mould and algae don’t just look bad — left long enough they work into paint and sealant and shorten the life of your cladding. A gentle wash on a sensible schedule is far cheaper than repainting or replacing surfaces down the track.