Pressure washers: what they clean well, and what they quietly destroy

A pressure washer is the most misused tool in the garden shed, and the damage it does is quiet: mortar joints grooved by a narrow jet, render stripped to patches, deck boards furred into splinters, window seals blown. The machine is genuinely excellent - within a narrow set of rules about distance, angle and nozzle. Those rules are all one idea: the jet's cutting power falls off explosively with distance, and everything about safe use is staying on the right side of that curve.

The nozzle-distance discipline

Start every job with the widest fan nozzle and the nozzle at arm's length from the surface, then work closer only until the dirt lifts. The narrow red pencil jets are for metal and stone stains at point-blank range in expert hands - they will carve grooves into concrete, gouge timber and shatter mortar, so treat them as tools you own but do not use. Hold the jet at a shallow-ish angle to the surface rather than dead-on: it gets under dirt instead of drilling into the material. Keep the jet always moving - a stationary jet in one spot for three seconds is how stripes and scars happen - and never wash downward across a joint you do not want water forced into.

What stays off the list

Painted render and aged pointing (the jet strips or blasts out what took a tradesman hours), asphalt roofs - loose granules gone for good - car paint at close range, anything electrical, and window glazing seals. Old soft deck timber washes into fuzz; use the widest fan, the right deck cleaner, and accept a gentle touch. And never operate the machine from a ladder: the kick when the trigger pulls, aimed wrong, is a fall waiting to happen - wash ground-level surfaces and use a telescopic lance for the rest, feet on the ground.

The prep that makes it fast and safe

Close windows and doors on the wall being washed; sweep first so the jet is not firing grit like sandpaper; cover soft plants and give the lawn a pre-soak so detergent does not burn roots; and keep detergents to the washer's own low-pressure detergent nozzle, applied then rinsed - never through the high-pressure jet. After any pre-paint wash, the clock matters more than the shine: timber and masonry must dry fully before paint or stain goes on, which is the whole subject of painting over damp - wash in dry weather, wait the honest number of dry days, then paint.

Used this way the washer earns its garage space twice a year: paths and patios in spring, walls and fences before winter - slots that fit naturally into the spring reset and the autumn checklist. For anything the jet cannot reach or should not touch - high walls, fragile roofs, anything structural - the professional-window has the same logic as the fence-and-shed maintenance questions: the machine is for surfaces you can stand next to, and everything else is a ladder-and-expertise problem.