Home › Blog › What You Should Never Power Wash
Published June 5, 2026 · By PowerWashingExpert Field Team · ~8 min read
Quick answer: Never aim a pressure washer at a roof, old or soft mortar, AC condenser fins, electrical components and meters, painted or stained wood, windows, screens, vehicles, or anything with lead paint. High pressure strips, gouges, drives water where it should not go, and voids warranties. Those surfaces get soft washed at low pressure with the right chemistry instead. Hard flatwork like concrete driveways takes pressure. Everything fragile, sealed, painted, or above eye level usually does not.
A pressure washer is a powerful tool, and that is exactly the problem. The same 3,000 PSI that strips winter grime off a concrete driveway will shred a roof, blow water behind your siding, and flatten the fins on your air conditioner in seconds. Most of the damage we get called to assess in Metro Detroit was not caused by dirt. It was caused by someone with a rented machine pointing it at the wrong surface. Here is the list of what to keep the wand away from, and what to do instead.
This is the big one. Never pressure wash asphalt shingles. The protective mineral granules that give a shingle its life are held in an asphalt binder, and high pressure blasts them straight off. You end up with a roof that looks briefly cleaner and ages years overnight. Worse, pressure drives water up under the shingles and into the deck, and it voids nearly every shingle manufacturer's warranty.
The black streaks on a Metro Detroit roof are a hardy algae called Gloeocapsa magma, and you kill it with chemistry, not force. Roofs get soft washed: low pressure, a cleaning solution that does the work, a gentle rinse. The split between high pressure and low-pressure soft washing is the whole subject of our soft wash vs power wash guide, and the roof is the clearest case for soft wash there is.
Newer brick in sound shape can handle controlled pressure. Old brick and the mortar between it often cannot. Decades of Michigan freeze-thaw leave mortar joints soft and crumbling, and a pressure washer will carve that mortar right out of the joint. On the older homes around Royal Oak, Ferndale, and the historic Detroit neighborhoods, that is not a cosmetic issue. Open joints let water into the wall and undermine the masonry.
Aged masonry gets cleaned at low pressure with a masonry-safe cleaner, and any failing joints get repointed by a mason. If a crew shows up ready to blast a 1920s brick house at full pressure, send them home.
The condenser unit sitting next to your house is wrapped in thin aluminum fins that bend if you look at them wrong. Pressure flattens them, airflow drops, and the unit works harder and dies sooner. Clean a condenser coil with a garden hose and a dedicated coil cleaner, rinsing gently from the inside out. The same goes for dryer vents, exhaust caps, and anything with delicate metal or moving parts. The pressure washer stays in its case for all of it.
Water and electricity is an obvious one, but people forget the exterior electric meter, outdoor outlets, light fixtures, and the service entrance when they get into a cleaning rhythm. Forcing water into any of these creates a shock hazard and can short the circuit. We cover and avoid all exterior electrical when we wash a house, and we never aim pressure at a meter or panel. If grime is building up around a fixture, wipe it by hand with the power off.
Decks, fences, and painted wood siding are easy to ruin with pressure. High PSI gouges soft cedar and pine, leaves a fuzzy raised grain that needs sanding, and tears paint and stain off in strips. A deck can be cleaned beautifully, but it is done at low pressure with a wood-safe cleaner, working with the grain. The exception is deliberate paint stripping as prep for a repaint, and even that is a controlled process, not a side effect of cleaning. If your goal is a clean deck you can re-stain, low pressure and chemistry get you there without chewing up the boards.
Pressure forces water past window seals and into the frame and wall cavity, where it has no way out. It can crack older single-pane glass and blow the seal on a double-pane unit, which leaves permanent fog between the panes that only a glass replacement fixes. Screens tear or deform. Windows are washed by hand or rinsed at low soft-wash pressure as part of a house wash. The wand never touches the glass.
People love to pressure wash their cars and trucks. At a true low-pressure setting with a wide tip held well back, a rinse is fine. The damage happens when someone uses a narrow tip up close, which chips paint, forces water past door and window seals, strips wax, and can dent thin body panels. If you are going to rinse a vehicle, keep the pressure low, the tip wide, and the distance generous. Better yet, use a hose and a mitt.
This one is a safety issue, not just a damage issue. Homes built before 1978 may have lead-based paint, and pressure washing flaking lead paint scatters contaminated chips and dust across your yard, which is a real hazard around kids and gardens. The EPA's lead-safe rules govern how older painted surfaces are handled. If you have an older Metro Detroit home with failing paint, that is a job for a lead-safe certified contractor, not a pressure washer.
Here is the simple test we use. If a surface is fragile, sealed, painted, covered in living growth, or above eye level, it almost always needs soft washing, not pressure. Roofs, siding, wood, screens, and old masonry all live in that group. Hard, durable flatwork like concrete driveways, sidewalks, and parking lots takes pressure with the correct tip and technique. When something sits in the gray area, the move is to test an inconspicuous spot first and adjust, which is exactly what a professional does before committing.
Knowing which method a surface needs is most of the job. The other half is timing, and we lay out when to clean each exterior surface across the Michigan season in our seasonal cleaning guide. For the surfaces that genuinely do take pressure, like a salt-loaded driveway or a commercial parking lot, the right pressure and chemistry get a great result safely.
If you are not sure whether your project needs pressure or soft washing, that is exactly the call to make before someone causes damage. We assess the surface, pick the method, and tell you straight if part of the job should not be pressure washed at all.
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No, not with pressure. High pressure strips the protective granules off asphalt shingles, voids most manufacturer warranties, and forces water under the shingles into the deck. Roofs get soft washed instead, with low pressure and a cleaning solution that kills the black algae streaks chemically. Anyone running a pressure wand across your shingles is shortening the life of the roof.
Newer brick in sound condition can take controlled pressure, but old or soft mortar cannot. High pressure blasts deteriorated mortar out of the joints, and on historic Metro Detroit homes that can mean real structural and water-intrusion problems. Aged masonry should be cleaned at low pressure with the right chemistry, and any failing joints should be repointed, not blasted.
You bend the condenser fins flat, which chokes airflow and drops the unit's efficiency. Those thin aluminum fins are not built for pressure. A condenser coil should be cleaned with a garden hose and a coil cleaner from the inside out, gently, never with a pressure washer. The same caution applies to dryer vents and any exterior mechanical equipment.
Carefully, and only at low pressure. High pressure gouges soft wood, tears off paint and stain, and leaves fuzzy raised grain that has to be sanded. Decks and painted siding are cleaned at low pressure or soft washed with a wood-safe cleaner. If you are stripping failing paint for a repaint, that is a prep step done deliberately, not an accidental result of cleaning.
Pressure forces water past the seals and into the window frame and wall, and it can crack older single-pane glass or blow out the seal on a double-pane unit, causing permanent fogging between the panes. Windows are washed by hand or with a soft wash rinse at low pressure. The pressure wand belongs nowhere near the glass.
If the surface is fragile, sealed, painted, organic-growth covered, or above eye level, it usually needs soft washing. Roofs, siding, wood, screens, and old masonry fall in this group. Hard flatwork like concrete driveways and parking lots take pressure with the right tip. When in doubt, a reputable Metro Detroit crew tests an inconspicuous spot before committing to a method.
PowerWashingExpert is a Metro Detroit exterior cleaning company serving residential and small commercial properties across Oakland, Macomb, and Wayne counties. Our crews match the method to the surface, soft washing the fragile stuff and reserving pressure for the flatwork that can take it. Free quotes, written estimates, no contracts. Call us or request a quote online.