The green side of the fence: why one face always grows a coat
Green growth favours one face because that face barely sees the sun. In Sydney, south-facing and tree-shaded fence panels stay damp long after rain, and algae and mould need only moisture and shade. The fix depends on the material: timber wants a low-pressure soft wash, while BlueScope's TB-4 bulletin calls for gentle fresh-water washing on Colorbond — never a harsh blast.
The sun does the accounting
Stand at your back fence and check the compass. In the southern hemisphere, the south face of anything gets the least direct sun — and a fence line hemmed in by a neighbour's hedge or the shadow of the house gets almost none. That face stays wet for hours after rain and holds overnight dew well into the morning. Algae and mould don't need soil. They need moisture, shade and a surface that stays damp. A shaded fence panel is all three.
That's why the growth maps so neatly. The green coat sits on the south side, thickens toward the bottom of the palings where ground moisture wicks up, and runs hardest behind shrubs where air barely moves. The street side of the same fence — same material, same age, same weather — stays clean because it dries by mid-morning. It isn't a fault in the fence or the finish. It's a microclimate, and it will keep doing exactly this until someone washes it properly.
Timber forgives a soft wash, not a pressure gun
A pressure gun will strip green off timber in seconds, and it will take the timber with it. High pressure furs the grain, blasts out the softer wood between growth rings and leaves a surface that grabs dirt and spores faster than before. Soft washing works the other way around: low pressure, a cleaning solution that kills the growth and its spores, then a controlled rinse. The green dies and lets go. The timber keeps its surface, and the regrowth clock starts from zero instead of from a scarred, thirsty face.
Be clear about what a wash cannot do. It won't reverse grey UV weathering — that's the timber itself changing colour, not a film sitting on top. It won't fix rot, a leaning post or a lifted paling. What it does is show you the truth: once the coat is off, you can see whether the fence needs oil, stain or a carpenter. If a re-oil is on your list, wash first. Coating over live mould just seals the problem in.
Colorbond is painted steel, and BlueScope says so
Colorbond is steel wearing a baked-on coat of paint, and the people who make it are specific about its care. BlueScope's Technical Bulletin TB-4 requires regular fresh-water washing of coated steel, more often near marine environments, and warns against harsh treatment of the surface. That matters on Sydney's harbour and coastal fringe — Manly, Mosman, the Eastern Suburbs — where salt rides the sea breeze and settles on every panel the rain doesn't rinse.
So a green Colorbond fence gets a different job from a green timber one. No aggressive pressure that can damage the coating, no harsh treatment the bulletin warns against — a gentle wash that lifts the growth and the salt together, then a thorough fresh-water rinse. The sheltered lower sections and the shaded face need the most attention, because they're precisely the parts natural rainfall never reaches. Done right, the panel comes back to its actual colour, which most owners haven't seen in years.
One green panel is a boundary problem
One furry panel is not one furry panel. Spores don't respect the joins — if the conditions along your boundary grew a visible coat in one spot, the neighbouring panels are colonised too, just a season behind. Wash a single panel and you get a patchwork: one bright rectangle in a dull run, with regrowth creeping back in from both sides. The sensible unit of work is the boundary, not the panel. Clean the whole run and every section starts from the same day zero.
Then accept the schedule the sun sets. The shaded face will always green up first — expect it to need attention more often than the sunny side, and plan for that rather than being surprised by it. A whole-boundary clean also tells you the real state of things: which posts are soft, where the coating is chalking, which panels the hedge is holding wet. That's information worth having before a cleaning job quietly becomes a replacement.
A firm number for the whole boundary
Fence work doesn't get a flat rate, because a flat rate would be a guess. Length, height, growth, access and material — timber and Colorbond are different jobs — all move the price, so Schmick quotes fences per job. The instant quote takes about 60 seconds and returns a firm, bookable price, and that price holds unless the place turns out to be materially different from what you described. No inspection theatre, no waiting for a callback.
If the fence has grown a coat, the shaded side of the house usually has too — the same microclimate works on render, weatherboard and paths. Bundling services on one visit saves 5 to 15 per cent, so it's worth pricing the soft wash or the driveway at the same time. Either way, start with the number. The green took years to arrive; finding out what it costs to remove takes about a minute.