Will Water Blasting Strip the Paint Off My Fence?
Sometimes — and That Tells You Something

The short answer: if the paint is sound, a careful wash will not take it off. If moss has been living in it for years, it very well might — and when it does, the wash has not caused the problem. It has found it.

Moss does not grow on healthy paint. It needs somewhere to hold, which means a coating that has already gone chalky, cracked or porous. By the time there is a green crust on a fence, the paint underneath has usually finished its working life. It is still there, but it is no longer stuck down.

What the Wash Found

On this fence the moss and the paint came off together. Keeping the lance well back did not separate them, because there was nothing holding the paint down any more. By the end of the wash the lower section was bare timber, the length of the run.

Worth saying plainly: that is not a disaster. Paint that comes off under a wash was going to come off anyway — in sheets, over the next couple of winters, somewhere less convenient. What it does do is change the job on the spot, and that is a conversation to have before any paint is opened, not after.

Why Not Just Paint the New Part?

That was the original request. The fence had been raised for privacy, so there was a new section of palings sitting on top of the old rails — two timbers of very different ages.

Fresh paint on new timber next to twenty-year-old paint does not blend. It draws a line exactly where you were hoping nobody would look. If the two halves are meant to read as one fence, they have to finish the same — which is why washing the old half was in the plan to begin with.

The Thing That Decides the Price Is the Construction

People quote fences by the metre in their heads. It is the wrong unit. This one has boards on both faces, so every metre is two metres of surface, and the lower half is open rails with gaps between them — edges, ends and undersides that no roller will reach.

A flat, one-sided fence of the same length is a fraction of the work. So when you are comparing prices, the question is not how long it is. It is how many faces there are.

Mask the House Before You Spray, Not After

This fence runs close to the weatherboards, and the lower section has gaps between the rails. Spray it from the far side and black paint goes straight through those gaps at the house. So the wall and the windows went under plastic sheeting first.

Fine black overspray on a white weatherboard house is not something you wipe off. It sits in the grain and in the texture of the paint, and the fix is repainting the wall.

So Should You Wash It First?

Yes — but go in knowing it might change the job. If your fence is green and the paint is old, there is a real chance the wash leaves you with bare timber and a bigger paint job than you planned. The alternative is painting over moss and failing paint, which looks fine for one season and then lifts.

Eight hours, $850 — washing and painting, both faces, with twelve months on the work.