How to clean pavers, brick & sandstone

Paved patios and pool surrounds take a beating in Canberra. Between the damp, cold months and shaded courtyards that never quite dry out, it doesn't take long for a tidy paved area to turn green, slippery and tired-looking. The good news is that most paving cleans up beautifully — but only if you match the method to the material. Concrete pavers, clay brick pavers and natural sandstone all behave differently, and treating them all the same is how surfaces get damaged.

Know what you're cleaning first

Before you point a pressure washer at anything, work out what the paving actually is. Poured or moulded concrete pavers are hard-wearing and tolerate a fair bit of pressure. Clay brick pavers are tough on the face but can be brittle at the edges and around the mortar. Natural sandstone (and limestone) is soft and porous, and needs a gentle, low-pressure approach — more on that below.

The problems are usually the same across all three: black mould and algae, moss and weeds sprouting in the joints, crusty lichen spots, dark leaf and tannin staining under trees, and chalky white efflorescence where salts have risen to the surface. Each responds best to treatment rather than brute force.

The general method for concrete and brick pavers

For hard-wearing concrete and most brick paving, a straightforward process gives the best, longest-lasting result:

1. Sweep the area to clear loose leaves, grit and debris.
2. Treat first. Apply an appropriate mould and algae treatment and give it time to work, rather than relying on the machine to do everything.
3. Pressure wash with a flat surface cleaner attachment instead of a narrow wand. The surface cleaner spins the water evenly across the paving and leaves a clean, stripe-free finish — narrow tips leave zebra stripes and gouge marks.
4. Re-sand the joints. Sweep fresh jointing or paver sand into the gaps once everything has dried.

That last step matters more than people expect. This is very much a treat-first job rather than a blast-first one — the same thinking behind soft washing vs pressure washing, where a cleaning solution does the heavy lifting and the water simply rinses it away.

Sandstone: go gentle

Sandstone deserves its own rules. Because it's soft and porous, it needs low pressure and a pH-neutral cleaner — essentially a soft-wash approach. Two things damage it fast: acids etch and discolour the stone (the same goes for limestone), and high pressure pits and erodes the surface, leaving it rough and patchy. If in doubt, dial the pressure right back and let the cleaning solution do the work. You can't undo a pitted sandstone patio.

Brick and older mortar

Older brick paving and anything with lime or soft mortar needs a careful hand too. Too much pressure can blow out the mortar joints and cause spalling — the surface of soft or aged bricks flaking away. Keep the pressure moderate, keep the tip moving, and never park a narrow nozzle close to the brick face.

Moss and weeds in the joints

Moss and weeds growing between pavers are a joint problem, not just a surface one. The trick is to kill or treat them first, remove them, then re-sand. If you simply blast them out with the pressure washer, you strip out the jointing sand along with them — and bare joints let moss and weeds come straight back, often worse than before. Treat, remove, re-sand: that order is what keeps them away.

Sealing and pool surrounds

Once pavers or sandstone are clean and dry, sealing is worth considering. A good sealer helps the surface resist staining, moss and general weathering, and makes every future clean quicker and easier.

Around pools, cleaning is also a safety issue. Algae films make surrounds slippery and unsafe underfoot, so it pays to clean them regularly. Keep in mind that pool water — whether salt or chlorine — also weathers the surface over time, so pool paving generally needs a little more attention than a dry courtyard.

A quick Canberra note

If your paving is in a shaded courtyard or a south-facing patio, expect moss and mould to establish quickly through the damp, cold months. These spots rarely get enough sun to dry out, so regular treatment and improving airflow where you can will do more good than an annual heavy clean.

What to avoid

• Acids on sandstone or limestone — they etch and permanently discolour soft stone.
• Holding a turbo or pencil tip too close — it leaves marks, rings and lasting damage.
• Blasting out all the jointing sand — it loosens the pavers and opens the door to weeds and moss.

FAQs

Can you pressure wash sandstone?

Only at low pressure with a pH-neutral cleaner — never use acids. Sandstone is soft and porous, so it's better treated as a soft-wash job rather than blasted with high pressure.

Do you need to re-sand pavers after cleaning?

Yes — pressure washing removes the joint sand between pavers. Re-sanding locks the pavers back in place and slows weeds and moss returning.

How do you stop moss coming back on pavers?

Treat and remove it rather than just blasting it out, re-sand the joints, seal the surface, and improve sun and airflow where you can so the area dries out faster.

Will pressure washing damage brick pavers?

It can — too much pressure can blow out old mortar or spall soft brick. Use moderate pressure and the right technique, especially on older paving.