How to Clean a Patio or Paver Surface

A patio is where a lot of people learn — the hard way — what a pressure washer can cost them. The pavers come up gleaming, the transformation is instant and satisfying, and then over the following weeks the surface starts to feel loose underfoot, gaps open, weeds appear. The washing did not damage the pavers. It quietly removed the thing that was holding them together. Understanding that one mechanism is most of what separates a clean patio from a clean patio that stays sound.

What is actually holding a patio together

Here is the counterintuitive heart of the whole subject. On a paver surface, the pavers are not what keeps things stable — the sand packed into the joints between them is. That joint sand does two jobs at once. It locks the pavers against each other so they do not rock or shift underfoot, and it fills the narrow gaps where weeds would otherwise find a foothold.

A high-pressure stream aimed into those joints scours the sand straight out. The immediate result looks spotless, which is exactly what makes the mistake so easy. But with the sand gone, the pavers begin to shift and separate over the following weeks, and weeds move into the emptied gaps. What felt like a thorough cleaning had, underneath, undone the structure of the patio. So the guiding principle is not only "protect the surface of the pavers" but "protect the joints between them" — and that means lower pressure, a wide-angle tip, keeping your distance, and never aiming the stream straight down into a joint.

Different patios, different tolerances

The right amount of caution depends on which of a few common surfaces you have:

• Pavers (concrete or clay) live and die by their joint sand. Gentle cleaning and re-sanding are the twin priorities.
• Natural stone varies enormously — some types are far softer, more porous, or more easily etched than they look. A test spot and a gentle method matter most here.
• Poured concrete patios are more durable and behave much like other concrete, though even they can etch and stripe under too much force.

When you are genuinely unsure how much force a surface can take, pressure washing versus soft washing is a good reference for erring toward the gentle side — which, on a patio, is nearly always the right side.

Cleaning without excavating the joints

The safe method leans on cleaner and patience rather than force, and it reads almost like the opposite of a power-washing session:

1. Sweep the patio to clear loose debris.
2. Rinse gently to wet the surface.
3. Apply an appropriate cleaner, follow its directions, and let it dwell so it can break down dirt, algae and moss.
4. Scrub stubborn spots with a stiff brush — reach for the brush, not for more pressure.
5. Rinse at low pressure, keeping the stream from digging into the joints.

If you do use powered equipment, keep it low, wide and well back. The mental image to hold is lifting the grime off the top, not excavating the seams between the stones. That single restraint prevents most of the damage this article is about.

Moss and algae in the shade

Patios that sit in shade or stay damp are magnets for moss and algae, and they are the growth people most often mishandle. Because these are living growth and not plain dirt, force is the wrong tool — it strips the visible green while leaving the roots behind, so it grows back, often within weeks. An appropriate cleaner treats the growth at its source. The same low-pressure approach used for algae on walls works on a patio floor.

And because moss and algae feed on moisture and shade, they will keep returning as long as those conditions hold. Improving drainage so water does not pool, and letting in more light where you can, does far more for the long term than any single cleaning. If the patio sits close to the house, keeping gutters clear so runoff is not dumping onto it removes one hidden source of the dampness that feeds the growth.

The step people skip: re-sanding

Because cleaning almost always washes at least some sand out of the joints, re-sanding is not an optional extra — it is what turns a clean patio into a clean, stable patio. The steps are straightforward:

• Let the surface dry fully before you add any sand.
• Fill the joints with appropriate joint sand, following the product's directions for sweeping it in and setting it.
• Do not skip it. Under-filled joints leave the pavers free to shift and the weeds free to move in — the very problems the cleaning was supposed to solve.

Re-sanding is the difference between a job that lasts and one that quietly comes apart. It is also a useful gauge of whether the cleaning went well: if you are watching sand pour out of the joints as you rinse, the pressure is too high or aimed too directly, and it is worth easing off before you finish. Watch, too, for pavers that rock underfoot, gaps that widen in the days afterward, etching on stone or concrete, or discoloration on natural stone from a cleaner that was too harsh — each is a sign to adjust rather than push on.

Most small patios are well within reach of a careful homeowner. It is worth calling in help when the area is large enough that re-sanding a great many joints becomes a project in itself, when stubborn moss or ingrained staining resists your efforts, when you have delicate or valuable natural stone and cannot predict how it will react, or when the job really calls for thorough re-sanding you would rather see done properly than half-filled.