A large share of Point Piper properties run down to the water, and many have a seawall, a set of stairs, a jetty, a pontoon or a boat shed at the bottom. These are the hardest-working structures on the property and the ones with the least margin for error when they are cleaned.
The reason is simple. Everything that comes off them goes straight into Sydney Harbour.
Why the waterline is a different job
On the rest of the property, runoff from a wash goes to garden and soil, which filters it. At the waterline there is no filter. Biocide, detergent, loosened paint and organic sludge enter the harbour directly.
That rules out the soft wash chemistry used on roofs and walls for anything that drains to the water, and it rules out careless work with anything else. Polluting waters is an offence under the Protection of the Environment Operations Act, and the harbour is the most visible place in Sydney to commit it. More: where the dirty water goes.
Seawalls
Most older seawalls around the peninsula are sandstone blocks, some with later concrete capping or repairs. The face sits in the splash zone, permanently wet and loaded with salt, marine growth and the black biological staining that sandstone collects everywhere in Sydney.
The cleaning question on a seawall is mostly a structural question first. Look for open joints, missing mortar, undermining at the toe, and blocks that have rotated or moved. Washing a wall with failed joints drives water into it, and on a seawall that is already happening twice a day with the tide. A wall that is moving needs a coastal engineer, not a cleaner.
Where the wall is sound, the capping and the dry upper face can be cleaned at low pressure with fresh water, working with the tide so nothing is done below the waterline. Never high pressure on the sandstone face. More: what high pressure does to sandstone.
Jetties and pontoons
Timber decking over water grows algae fast, and wet algae on timber is as slippery as ice. The commonest accident on a waterfront property is a fall on the jetty, not anything on the roof.
Timber jetties get a low-pressure clean with fresh water and a scrub, not a pressure wand. High pressure tears the soft early wood out of the board and leaves a furred, splintered surface that grows algae faster than before. Composite decking has its own warranty conditions on cleaning methods, worth checking before anyone starts. More: composite decking.
Check the fixings while you are there. Galvanised and stainless fasteners in the splash zone corrode, and a handrail bracket that has rusted through is a safety issue that cleaning will reveal rather than cause.
Boat sheds and harbour stairs
Boat sheds collect everything: salt on the walls, mould inside where air does not move, rust on roller doors and hinges, and bird droppings on any ledge over the water.
The inside of a shed is often the dampest space on the property. Ventilation does more than cleaning here, and stored timber, ropes and fabric should be dry before they go back in.
Harbour stairs are a combination of sandstone treads, concrete, and metal handrails. Treat them as three separate surfaces with three separate methods, and treat slip resistance as the main outcome. More: slip resistance on outdoor surfaces.
Timing
Work the low tide. Avoid strong onshore wind, which drives spray and overspray back onto the property and the neighbours. Autumn, after the summer boating season and before winter swells, is the natural point in the year.
Our broader guide on jetty, pontoon and seawall cleaning on Sydney Harbour covers approvals and access in more detail. For the rest of a Point Piper property through the year, see the Point Piper maintenance calendar.
