Pressure Washing vs. Soft Washing: What's the Difference?

Every week somebody calls me and says, "I need my house power washed." And every week we have the same little conversation. Because here's the thing. I'm probably not going to power wash your house. Not most of it, anyway.

I'm going to soft wash it.

That's not me being picky. They're two different jobs with two different tools. Pick the wrong one and a $200 cleaning can turn into a $2,000 repair. I've seen it happen on houses all over Atlanta, usually after somebody rented a machine from the hardware store on a Saturday.

So here's the real difference, from a guy who does both every day.

Pressure washing vs. soft washing at a glance

What pressure washing is actually good at

Concrete. That's the big one.

Your driveway is basically a rock, and it can handle a real beating. Red clay, tire marks, that green film on the shady side, the black gunk under the basketball goal. High pressure gets all of it. We use a surface cleaner on flat concrete, which is a spinning bar under a round cover. It cleans evenly, so you don't end up with those zebra stripes you see on DIY jobs.

If your driveway or walkway looks rough, that's a driveway cleaning job, and pressure is the right call.

Your siding is a different story.

What soft washing is (and why "soft" doesn't mean weak)

People hear "soft" and figure it doesn't work as well. It's the other way around.

That green and black stuff on the north side of your house is alive. It's mold, mildew, and algae, and around here it loves our humidity. When you blast it with high pressure, you're basically mowing it. The top comes off, but the roots stay down in the pores of the surface. Give it one humid Georgia summer and it's back.

Soft washing kills it instead. We apply a properly diluted cleaning solution at low pressure, let it sit long enough to do its job, then rinse it off gently from the top down. The growth is dead, not just trimmed. That's why a soft-washed house stays clean a lot longer than one that got blasted.

It's how we handle every house wash and every roof cleaning we do.

Which one does your home need? Surface by surface

Vinyl siding: soft wash

Vinyl siding overlaps like shingles to shed rain coming down. High pressure sprays up and under those laps and pushes water into your walls. Now you've got wet insulation and maybe mold growing where you can't see it. Not worth it.

Roofs: soft wash only

Those black streaks on your shingles aren't dirt. They're a type of algae called Gloeocapsa magma, and it feeds on the limestone filler in asphalt shingles. Pressure washing a roof knocks off the granules, and those granules are what protect your shingles from the sun. Most shingle makers warn against pressure washing for exactly that reason. Soft washing kills the algae and leaves the granules alone.

Brick and stucco: soft wash

Stucco can crack and chip under high pressure. Older brick can lose mortar between the joints. A soft wash with a gentle rinse cleans them without chewing them up.

Wood decks and fences: a little of both

Wood sits right in the middle. It needs a cleaner to kill the mildew and the gray, but it also needs some pressure. Just not much. Too much and the wood gets fuzzy and splintered, and you can't take that back. We keep the pressure low and use a wide tip. Here's more on our deck and fence cleaning.

Driveways and sidewalks: pressure wash, then treat

Concrete gets the pressure. But a lot of times we'll follow up with a soft wash treatment on the green spots. Pressure gets it clean. The treatment helps keep the green from coming right back.

Windows: neither one

Pressure on glass can blow out the seals. That one gets its own post: The Truth About Window Cleaning.

Before

After

"My neighbor's guy pressure washed his whole house and it looked great."

I believe you. It probably did look great. That day.

The damage from the wrong method doesn't always show up right away. Here's what I look for when I'm called out to a house that got blasted:

• Wood that feels fuzzy or furry when you run your hand over it
• Light and dark stripes across the driveway
• Chalky streaks on the siding, or paint peeling in spots
• A bunch of shingle granules sitting in the gutters
• Green coming back within a few months
• Foggy double-pane windows

Whoever you hire, ask them three things before they start. What pressure are you using on my siding? What are you putting on my roof? How are you protecting my plants? If they can't answer all three without blinking, keep shopping.

How often should you wash your house in Atlanta?

For most homes around here:

• House: once a year. If you've got a lot of shade or trees, the north side might want twice.
• Driveway and walkways: once a year, more if you're parked under pines.
• Roof: when you start seeing black streaks. A good soft wash usually buys you a few years.

Spring gets rid of the pollen. Fall gets the house ready for the holidays. Either one works.

Right tool, right surface. That's the whole secret.

James Mahone, owner, JR Pressure Pros