Sandstone and pavers are where a lot of well-intentioned weekend pressure washing goes wrong. Both are softer and more variable than the concrete most people practise on, and both punish a heavy hand in ways that do not show up until the surface has dried.
Why sandstone needs a different approach
Sandstone is a sedimentary stone with visible grain and a relatively soft, porous surface. Direct high pressure does not just clean it, it erodes it. What you get is a subtly pitted surface, often with visible wand marks where the operator paused, and because the freshly eroded stone is more porous than what was there before, it soaks up dirt faster from that point on.
The damage is usually invisible while the stone is wet. It appears a day later when everything dries and the light catches the texture differently.
Sandstone responds far better to a treatment that kills the organic growth in the pores, dwell time, and a wide fan tip at low pressure. Slower to do, and the surface keeps its face.
Pavers: the joints are the weak point
With pavers the units themselves usually survive pressure fine. The problem is the sand in the joints. High pressure strips jointing sand out in seconds, and once it has gone the pavers lose their interlock, start to rock underfoot, and let water down into the bedding layer where it undermines the whole area.
A properly done paver clean either works at a pressure that leaves the joints intact, or accepts that the sand will need replacing and re-sands as part of the job. What should never happen is stripping the joints and walking away, which is unfortunately the most common outcome of a hire-yard pressure washer.
Efflorescence is not dirt
The white chalky bloom that appears on pavers is efflorescence, mineral salts drawn to the surface as water moves through the unit. Cleaning it off with water alone often makes it worse, because you have added the very thing that transports the salts. It needs a specific treatment, and it can recur while the paving is still curing or if there is a drainage problem underneath.
Sealing afterwards
Both sandstone and pavers benefit from sealing after cleaning, more so than plain concrete, because both are more porous. On pavers, a sealer also helps stabilise the joint sand. The same rule applies as with a driveway: the surface must be fully dry first.
What good looks like
A properly cleaned sandstone or paved area comes back to an even tone across the whole surface with no banding, no wand marks, and joints still full. If you can see stripes, the pressure was too high or the pass pattern was wrong. If the pavers move underfoot afterwards, the joints have been stripped.
We clean sandstone, travertine, exposed aggregate and paved areas across the Brisbane metro, including pool surrounds in Grange, Carindale, Kenmore Hills and Birkdale. If you are not sure what your paving is made of, a photo is usually enough for us to tell you and to quote it properly.
