Why Does My Patio Go Green and Slippery?
And What Actually Takes It Off

Moss needs three things and a New Zealand back yard hands it all three: shade, damp, and something organic to feed on. A corner with a fence on two sides and planting around it stays wet long after the rest of the yard has dried, which is why that corner always goes first.

The Part That Matters Is Not How It Looks

Moss holds water. That is the whole problem. A mossy paver after rain behaves like a wet tile, and the people most likely to find that out are the ones least able to take the fall. The faint damp smell that comes with it is the second half of the story. Looks are the last reason to wash a patio, not the first.

Why the Head on the End of the Hose Decides the Result

A bare wand throws one jet. On a concrete slab that jet cuts stripes — you get the moss off and leave a corduroy pattern behind that shows up every time the light is low. A rotary concrete attachment spins its jets under a shroud instead, so the pressure lands evenly across the slab, and the spray stays under the hood rather than across the furniture and up the fireplace.

On the BBQ area at this house that head did something extra: it lifted old paint marks left on the concrete by earlier work around the property, along with the moss. That is a bonus rather than a promise — it depends on the paint and how long it has been sitting there.

The Honest Warning About Painted Timber

The fence in that corner was painted, and in places the paint had already lifted where moss had been working underneath it. The wash took that loose paint off with the moss. That is not damage — the paint was going anyway — but it does mean a return visit to touch it up, which happened the next day here.

If you are booking a wash on painted timber, expect it and plan the touch-up in. Anyone who promises you otherwise has not washed many fences.

How Long Before It Comes Back?

That depends on the spot, not on the wash. A shaded corner behind a fence will green up again sooner than an open driveway, because the conditions that caused it are still there. If you want the green held back longer, a moss treatment after the wash is the thing that does it — the wash alone only resets the clock.

Do Several Small Areas at Once

This is the practical bit. Each of these three areas on its own barely feels worth a call-out, which is exactly why they sit there annoying people for years. Together they came to two hours and $220, because the gear only comes off the van once.

See the full project — all three areas, before and after →