Can Pressure Washing Damage Your Patio? What You Need to Know

Can Pressure Washing Damage Your Patio?

The short answer is yes — used wrong, a pressure washer can do real damage to your patio. The longer answer is that with the right technique, the right pressure, and the right nozzle, pressure washing is safe and effective. Here's what you need to know.

How Pressure Washers Damage Paving

There are three main ways a pressure washer can damage your patio:

1. Etching the Surface

A narrow, high-pressure jet directed at one spot for too long will cut a groove into the surface. This is most visible on sandstone and concrete — you'll see lighter lines where the jet has been. Once etched, the surface can't be repaired without re-laying.

2. Blasting Out the Pointing

If you direct the jet into the joints between slabs, you'll wash out the sand, resin, or cement that holds them in place. Once the pointing is gone, the slabs can move, water gets underneath, and you're back to a sinking patio.

3. Stripping the Surface Off Sandstone

Indian sandstone has a riven, textured surface. A powerful jet at close range can strip that surface off, leaving a smooth, pale patch that looks nothing like the surrounding stone. It also makes the slab more porous and prone to staining.

How to Pressure Wash Safely

If you're doing it yourself:

• Use a wide fan jet, not a pinpoint jet — the wider the fan, the gentler the spread of pressure
• Keep the lance at least 30cm from the surface — closer isn't better, it's just more destructive
• Keep the jet moving — never hold it in one spot
• Angle the jet at 45 degrees — this directs the water across the surface, not into the joints
• Use the right pressure — 100–130 bar is plenty for most patios. More isn't better.

What Pressure Should You Use?

• Concrete paving: 120–150 bar — concrete can take it
• Indian sandstone: 100–120 bar — be gentle, keep the lance moving
• Porcelain: 120–150 bar — porcelain is hard, but still use a fan jet
• Block paving: 100–130 bar — be careful not to blast the sand out of the joints
• Natural limestone: Avoid pressure washing entirely — it's too soft

When to Call a Professional

If your patio is heavily stained, moss-covered, or hasn't been cleaned in years, a professional clean is worth it. We use surface cleaners — rotary attachments that clean evenly without the etching risk of a lance — and we know the right pressure for each material.

Request a free online quote for professional pressure washing.

MSJ Landscaping — pressure washing across South Manchester and Cheshire.