Can Pressure Washing Damage My Home's Siding?

Yes, it can. And the worst of it usually doesn't show up the day of the job.

If you're thinking about renting a pressure washer and doing your siding yourself, or you're vetting a company to do it for you, this is the question to ask first. Siding is where I see pressure washing go wrong more than anywhere else on a house, and fixing it costs a lot more than the cleaning ever would.

The short answer

Siding gets damaged when someone runs too much pressure, holds the tip too close, or sprays up at it instead of down. At low pressure with the right mix, most siding cleans up fine.

The machine doesn't know the difference. That part's on whoever's holding the wand.

How pressure washing damages siding

Vinyl gets brittle, especially when it's cold out, and enough force will crack a panel or pop it loose. Once it's cracked, you're not cleaning it anymore. You're replacing it.

Wood is softer. High pressure tears up the grain and leaves it fuzzy and splintered, and that raw wood soaks up water until you refinish it. On painted or stained siding of any kind, too much pressure takes the finish right off, and what started as a cleaning turns into a repaint.

The worst damage is the kind you can't see. Siding is built to shed water running down it. It isn't built for water driven up and under it at a few thousand PSI. Aim a pressure washer upward or straight into the seams and you push water behind the panels and into the wall, which is how people end up with mold and rot inside the house. You won't see it the day of the job. It turns up months later, when it costs a lot more to fix.

Which siding is most at risk

Any siding can be damaged, but some types are less forgiving than others:

• Vinyl cracks under pressure, and the overlapping seams make it easy to drive water behind it.
• Wood and cedar splinter and lose their finish fast.
• Fiber cement (like Hardie board) is tougher, but the manufacturer still calls for low pressure, and too much force chews up the paint and the caulk.
• Aluminum dents easily, and on older panels high pressure can strip what's left of the paint.
• Stucco chips and cracks, and once the surface opens up, water gets in.

Every one of those does better with less force. That's why soft washing exists.

Why rental jobs cause the most damage

The pressure washers you rent from the hardware store are strong, and nobody sets them up for siding before you drive off. Most people crank the pressure all the way up, grab a narrow tip because it "cleans faster," and stand too close to the wall. Any one of those can wreck a panel.

The rest of the damage shows up later. Spraying up under the laps soaks the wall behind them. Blasting the green film off without killing it means the algae grows right back. It feels like it's working while you're doing it. A season later the green is back, and sometimes there's water in the wall too.

The right way to clean siding

For most siding the answer is less pressure, not more. Soft washing runs at about garden-hose strength with a cleaning solution that kills the algae and mildew, so I can rinse it off without forcing water into the wall. Because it kills the growth instead of knocking it loose, the house stays clean a lot longer, too.

On a siding job I set the pressure for whatever your house is made of, keep the spray angled down so water runs off the laps instead of under them, and wet down your plants before and after. It takes longer than blasting it. It's also why nothing gets damaged.

Getting your siding cleaned

Wes's Waterworks is family-owned and owner-operated here in Marietta. When you book, you're dealing with me, not a call center.

Call or text me at 678-984-9542, or send me the details here. I quote off Google Earth, so you'll have a real number the same day without anyone coming out. If you want a ballpark first, here's what a house wash usually runs.

Serving Marietta, Kennesaw, Acworth, Woodstock, Powder Springs, Smyrna, and the rest of Cobb, Cherokee, Paulding, Fulton, and Bartow counties. See residential services for everything I clean, or the service areas page for the full map.

Common questions

Can you pressure wash vinyl siding? You can, but keep the pressure low, and for most homes a soft wash is the better call. Too much force cracks vinyl and drives water behind the panels. I set the pressure for the material on every house.

Will pressure washing my siding cause mold? It can. If water gets forced behind the siding and into the wall, it can sit there long enough to grow mold and start rot. Keeping the spray low and angled down keeps the water on the outside.

Is soft washing better for siding than pressure washing? For most siding, yes. It cleans without the force that damages panels, and it kills the algae instead of just knocking it off, so the walls stay clean longer.

How often should I clean my siding? With Georgia humidity, about once a year works for most houses. Shaded and north-facing walls grow algae faster and may need it sooner.