Best pressure washer for decks and fences

Decks and fences are where pressure washers do their most visible damage. Concrete forgives a mistake; softwood records it as a permanent fuzzy stripe. The specification that matters most on wood is therefore not the maximum figure on the box — it is whether the machine has a lower setting, and whether the maker publishes it.

The short answer

Cleaning units, and why wood cares about both numbers

Generac describes PSI and GPM as figures that have to be read together: pressure lifts dirt, flow carries it away. Multiply them and you get cleaning units, which is the only single number that compares machines fairly.

On a driveway you want the 6,000. On a cedar deck you want something closer to the 2,200 — and note that eco mode drops flow as well as pressure, which is the wrong half to lose when you are rinsing. This is why nozzle choice matters as much as the machine setting: a wide fan reduces the force per square inch without reducing the water available to carry debris away.

The number nobody publishes

The two, on published figures

1. Greenworks 60V — the one with a published lower gear

Three thousand PSI and 2.0 GPM at maximum, and — the reason it leads this page — a published eco mode at 2200 PSI and 1.0 GPM. Having two stated operating points on one machine is exactly what a deck job wants: full power for the concrete path, eco for the boards.

Cordless also removes the cord from a job done on a raised platform with railings and furniture in the way, which is a real practical gain rather than a spec-sheet one.

The limits: up to 30 minutes of runtime, so a large deck is a two-battery job, and Greenworks does not publish a nozzle count, hose length or detergent capacity for this model.

#ad Check the Greenworks 60V 3000 PSI Cordless Pressure Washer price on Amazon — how we're funded.

2. Sun Joe SPX3000 — the gentler machine with more nozzles

Rated at 2030 PSI and a certified 1.2 GPM, which is about 2,436 cleaning units — close to the Greenworks eco mode, but as the machine's normal state rather than a reduced one. On wood, starting from a lower baseline is a defensible way to buy.

Five quick-connect nozzles are the practical advantage. The 40 degree fan is the deck nozzle, the 25 degree is for stubborn algae at a distance, and the soap nozzle carries the cleaner. Two removable 0.9 L detergent tanks let you switch between a wood cleaner and a rinse without emptying anything.

It is corded, at 35 ft of cord and 20 ft of hose, so the reach around a deck is bounded by an outlet. And with no published eco mode, the only way to turn it down is the nozzle and your distance.

#ad Check the Sun Joe SPX3000 Electric Pressure Washer price on Amazon — how we're funded.

A method that does not need a published safe PSI

1. Fit the widest fan nozzle you own — the 40 degree, never the 0 degree. Nozzle angle changes force per square inch more than any dial on the machine.
2. Start at 18 to 24 inches from the surface, on a board that does not show — the underside of a step, the back of a fence panel.
3. Move closer in small increments until the wood cleans. Stop the moment the grain starts to raise or fur; that is your limit for that board on that day.
4. Work along the grain, keep the nozzle moving, and overlap passes. Stopping in one place is what carves the stripe.
5. Let it dry fully before sealing. Washing raises moisture content, and sealing over wet wood traps it.

Full nozzle detail is in our pressure washer nozzles guide, and the hard-surface case is in pressure washing a driveway.

The warning that still stands

The U.S. Consumer Product Safety Commission has warned that pressure washer streams can cause serious injury, including driving material under the skin — an injury that can look minor and be anything but. On a deck the added hazards are height and a wet surface underfoot. Wear eye protection, keep both feet planted, and never brace a railing with the hand holding the wand.

Who should skip both

• Old, soft or splintered decking. If boards are already failing, washing accelerates it. Scrub with a deck cleaner and a stiff brush instead.
• Painted or opaque-stained wood. Pressure lifts coatings unevenly, which turns a cleaning job into a stripping job you did not plan.
• Composite decking with a warranty. Check the manufacturer's own limit first; several publish a maximum PSI for their boards, and that published figure beats anything on this page.

What we cannot tell you

We have not washed a deck with either machine. Neither manufacturer publishes a safe pressure for wood, a nozzle-by-nozzle force figure, or a recommended standoff distance. Greenworks publishes no nozzle count, hose length or detergent capacity for its 60V machine. The cleaning-unit arithmetic above is ours, and it compares machines — it does not tell you what your particular cedar will tolerate. Only a test board does.