Pressure Washing vs. Soft Washing: What Is Actually the Difference?

People call and say they want their house pressure washed. What almost all of them actually want is their house to stop looking green, and in most cases pressure washing is not how you get there.

The two terms get used like they mean the same thing. They do not, and the difference is worth about five minutes of your time before you hire anybody, including us.

Pressure washing is force

Pressure washing means using high-pressure water to physically remove what is stuck to a surface. The water does the work by hitting the dirt hard enough to knock it loose.

That is exactly right for hard, dense materials:

• Concrete driveways, walks, and slabs
• Sound brick and masonry
• Curbing and street aprons
• Parking lots and drive lanes

These surfaces can take the force. They are hard enough that the water moves the dirt without moving the material.

Soft washing is chemistry

Soft washing means applying a cleaning solution at low pressure, letting it work for a few minutes, then rinsing it off. The solution kills and releases the organic growth. The water just carries it away.

That is the right method for anything that force would damage:

• Vinyl, fiber cement, and painted siding
• Soffits, fascia, and gutters
• Wood decks, fences, and railings
• Stucco
• Screened enclosures
• Older masonry with soft mortar

The pressure in soft washing is closer to a strong garden hose than to a pressure washer. That surprises people, and then they see the result and stop worrying about it.

Why more pressure is not better

Here is the part that costs homeowners money.

Green on the north side of your house is a living thing. It has roots in the surface. If you blast it off with high pressure, you remove what you can see and leave what you cannot, so it comes back faster than it would have. Meanwhile you have driven water up behind the siding, where it will sit, and you may have carved a permanent stripe into the material.

A cleaning solution kills it. That is the difference between clean for a season and clean for a year.

On concrete the same logic runs the other direction. A surface cleaner at a sensible pressure is the fastest way to get a driveway evenly clean. Trying to soft wash a driveway and calling it done just leaves you with a slightly lighter dirty driveway.

How to tell which one you need

The simplest test for a homeowner: could you scratch it with a key?

If yes, that surface is soft enough that high pressure will mark it. Siding, wood, screens, and painted anything all fall in that group. Those get soft washed.

If no, and it is a poured slab or solid masonry with joints in good shape, it can take pressure.

A lot of properties need both on the same visit. A typical house wash job here is the siding soft washed and the driveway and walkway pressure washed with a surface cleaner, and there is no conflict in doing both, as long as whoever is holding the wand knows which is which.

What to ask whoever you hire

If someone quotes you a house wash, ask what pressure they run on siding. If the answer involves a number in the thousands, or they cannot answer, that is your answer.

It is easier to explain this once than to fix it after.