Pressure Washing: 4 Things You Should Never Spray

TL;DR: A pressure washer can strip paint, crack mortar, and wreck a roof in seconds. Here are the four surfaces to never blast — and what to do instead.

_Last reviewed: July 2026 · 3 min read_

A pressure washer is powerful enough to cut wood and strip paint, so the most important skill is knowing what not to spray. Never aim high pressure at asphalt roof shingles, painted wood trim, electrical or AC units, or brick mortar joints. Each of those can be permanently damaged in seconds — and the repair costs far more than the dirt you were trying to remove.

Can you pressure wash a roof?

Not with a standard pressure washer. The force strips the protective granules right off asphalt shingles, taking years off your roof's life and voiding many warranties. It can also drive water up under the shingles. If your roof has moss or algae, use a low-pressure "soft wash" with the right cleaning solution, or hire a roof-cleaning pro. (While you're thinking about the roof, here's a roof inspection checklist.)

Why shouldn't you pressure wash painted wood?

High pressure peels paint and splinters soft wood fibers, leaving a fuzzy, damaged surface that needs sanding and repainting. On painted trim, siding, and old wood, drop the pressure way down, use a wide fan tip, keep the wand moving, and stay well back. Better yet, soft-wash painted surfaces with a cleaning solution and a soft brush.

Is it safe to pressure wash around outlets and AC units?

No. Water and electricity don't mix, and a pressure washer can force water deep into outdoor outlets, light fixtures, and the delicate fins of an air-conditioning condenser. Bent AC fins restrict airflow and make the unit work harder. Keep the spray well clear of anything electrical, and clean AC coils gently with a garden hose and a fin comb instead.

Will pressure washing damage brick?

It can. Blasting mortar joints up close hollows out the mortar that holds the wall together, leading to loose bricks and water intrusion. If you pressure wash masonry, use a wide fan tip, keep moderate pressure, and stay at least a foot or two back. Crumbling joints are a sign you need repointing, not more pressure.

Save your settings for next time

The right tip, pressure, and distance for each surface are easy to forget by next season. Jot down what worked — "wide tip, low pressure for the deck; soft-wash only on painted trim" — so you're not relearning it every spring. Okoniq Property Hub keeps those notes with the rest of your home's records, in one private place in your browser. The U.S. Consumer Product Safety Commission also publishes safety guidance worth a look before you start.

Frequently asked questions

What can you safely pressure wash?

Concrete driveways, patios, sidewalks, fences (with care), and vinyl siding generally handle pressure washing well — using the right tip and a safe distance.

What pressure is safe for a house?

Use a wider (lower-pressure) tip for most home surfaces and start farther away, moving closer only if needed. Hard surfaces like concrete tolerate more than wood or siding.

Should I hire a pro?

If you're cleaning a roof, multi-story exterior, or delicate masonry, a professional with soft-wash equipment is worth it — they carry the insurance for the risk.

Okoniq Property Hub helps homeowners and landlords keep maintenance, bills, and contractor info in one calm place. Get started free.

FAQ

How much does it cost to soft wash a roof instead of pressure washing?

Professional roof soft washing typically runs $300–$600 for a single-family home, depending on roof size and local rates — far less than replacing damaged shingles.

What is the difference between pressure washing and soft washing?

Soft washing uses low pressure and a chemical cleaning solution to break down dirt, algae, and mold, while pressure washing relies on high-pressure water alone to blast surfaces clean.

Can pressure washing void my roof warranty?

Yes — many asphalt shingle manufacturers will void the warranty if you use high-pressure washing, because it strips the protective granules off the shingles.

What tip should I use on a pressure washer for painted siding?

Use a 40-degree (white) tip or wider for painted siding, keep the wand at least 12–18 inches away, and test on an inconspicuous spot first to avoid peeling paint.