How often should you wash and re-oil a fence?
Wash a fence once a year. Timber wants re-oiling every one to two years — sooner on a sun-hit western run, later in shade. Colorbond and coated steel need only a regular fresh-water wash, never oil. The shade side, where moss and mould gather first, sets your real cadence. Homes near the coast wash more often.
Once a year keeps the fence honest
A fence lives outdoors with no roof over it. Rain, pollen, road film and airborne mould all land on it and stay. Give every fence a wash once a year and you reset that build-up before it bonds to the surface. Do it in spring, after the wet months have done their worst and before summer bakes the grime on. One pass at the right pressure and a fence can look a decade younger.
Yearly is the floor, not the ceiling. A fence under a leafy canopy, beside a pool, or catching salt off the water will ask for a second wash before the year is out. You will know, because the low third goes green first. That green is algae and mould holding moisture against the surface, and moisture is what ages every material — timber, steel and masonry alike. Wash it off and the clock slows down again.
Timber drinks oil on a one-to-two-year clock
Bare timber that has been washed still needs feeding. Oil is what keeps the boards from drying out, cupping and going silver-grey. On most Sydney fences, re-oil every one to two years. A western or northern run that takes full afternoon sun burns through its oil faster — call that the one-year end. A sheltered or south-facing fence holds colour longer and can stretch toward two. The test is water: if it stops beading and soaks straight in, the oil is spent.
Re-oiling is not the same job as painting, and it is not maintenance you can defer forever. Once timber greys and the surface fibres lift, oil no longer soaks in evenly and the finish goes blotchy. At that point you are sanding back, not topping up. Wash first, let the boards dry for a few days, then oil onto a clean, dry surface. Skip the wash and you seal dirt and mould under the coat — which is how fences rot from the inside out.
Colorbond wants water, never oil
Colorbond and other coated-steel fences never take oil. The colour is baked into the coating, so all it wants is washing. BlueScope's Technical Bulletin TB-4 is explicit: coated steel needs regular fresh-water washing to remove the deposits that would otherwise sit and corrode it. A hose and a soft brush, or a gentle wash, is the whole routine. No oil, no sealer, no harsh chemicals — TB-4 warns against harsh treatment that strips the coating right off.
Location moves the dial. TB-4 tells homeowners within a few kilometres of the coast to wash more often, because salt-laden air settles on the steel and accelerates corrosion between rains. Rain rinses the exposed faces for you, but the sheltered spots it never reaches — under rails, behind posts, the back of a fence against a wall — are exactly where salt and grime concentrate. Those are the panels worth a deliberate wash a few times a year on an eastern-suburbs or Manly block.
The shade side sets the clock
Forget the calendar for a moment and read the fence. The shade side always fouls first. A run that never sees direct sun stays damp longer after rain, and damp is what moss, lichen and black mould need to colonise. That is why one face of a fence can look tired while the other still looks fresh. The greenest side is telling you your real washing interval, whatever the material sitting underneath the growth.
So set your cadence by the worst-affected panel, not the best. If the shady southern run is green again eight months after a wash, that is your number — wash twice a year and re-oil the sunny runs on their own slower clock. Cleaning cannot undo damage that has already set in, though. Timber gone punky and soft, or steel with the coating rusted through, is past washing. Honest fences get replaced, not scrubbed — the wash keeps a sound fence sound.
Your exact number, in about 60 seconds
Fence work is quoted per job. Price turns on length, material, how much growth has taken hold, access down the side of the house, and whether you want a wash only or a wash plus re-oil. That is too many variables for a rule-of-thumb figure, so Schmick prices each fence on its own terms rather than pretending one number fits every yard in Sydney.
The instant quote sorts it in about 60 seconds: describe the fence and it returns a firm, bookable price that holds unless the place is materially different when we arrive. Booking the fence alongside a house soft wash or gutter clean on the same visit trims 5 to 15 percent off the total. Get your exact number, then decide — no inspection visit, no vague estimate, just the figure.