Drainage is the biggest factor
Standing water is concrete's long-term killer. Water that sits on the surface through 8 hours of overnight chill, then heats in morning sun, expands and contracts the slab unevenly. Do this for a few winter seasons and you get surface delamination, spalling and accelerated sealer breakdown.
Walk your driveway and patio after the next big winter rain. Look for puddles that haven't drained within 30 minutes. Common causes:
- Settling soil at the slab edges altering the runoff path
- Blocked drainage grates from leaves + sand
- Negative slope toward the house wall (most common DIY-build mistake)
- Garden bed mulch creeping onto the slab edge and trapping water
Check your sealer condition
The simplest test: pour a cup of water onto the slab. If the water beads up like wax, your sealer is intact. If the water absorbs into the concrete and darkens the surface, you're overdue for a re-seal.
Winter is the right time to re-seal. The cooler temperatures slow the sealer cure so it penetrates deeper, and there's less UV to flash-cure the surface. We typically re-seal customer driveways in June-August.
Salt + coastal exposure
For homes within 5km of the coast (Scarborough through to Cottesloe and down to Fremantle), salt is doing measurable damage every winter storm. Salt crystals push into surface pores, expand on freeze-thaw cycles, and accelerate sealer breakdown by 30-50%.
The fix is dead simple: hose the slab down after every storm. Two minutes with a garden hose washes off the salt deposit before it can crystallise. It looks like nothing but it's the single highest-impact maintenance task you can do.
Moss and algae on shaded sections
South-facing alfresco floors, shaded paths, areas next to large trees — these zones don't dry properly through winter and become moss/algae hotspots. Beyond the visual issue, biological growth holds moisture against the slab and degrades the sealer.
Spot treatment with a 1:10 vinegar-water mix kills moss without harsh chemicals. Avoid chlorine bleach — it strips concrete sealer along with the moss. Brush with a stiff bristle (not wire), rinse, allow to dry, then spot-reseal if needed.
Our 20-minute winter checklist
This is what we do on our own driveways once a month June-August:
- Hose down after every storm. Salt washes off in seconds before it can damage anything.
- Sweep loose grit. Sand + leaf debris hold moisture against the slab — sweep, don't pressure-wash.
- Test sealer with a water cup. If it doesn't bead, plan a re-seal.
- Walk the edges. Look for settling, garden bed creep, blocked drainage.
- Spot-treat moss with the vinegar mix on any shaded sections.
- Note any new cracks > 2mm for spring inspection.
Twenty minutes a month. Saves your slab for an extra 10 years easily.
About Richard Marsh
Founder · CoastCrete · 20+ years on the tools
Richard founded CoastCrete in Perth after a decade of pouring driveways, alfrescos and pool surrounds across the metro. He writes the articles, answers the calls, and runs the crew personally on every job — so what you read here is the same advice he gives clients on-site every week.
Read more articles by Richard →Common questions
How often should I re-seal in Perth?
Every 3 years within 5km of the coast (Scarborough, Trigg, Cottesloe). Every 5 years inland. Indoor polished concrete: 5-7 years between burnishes.
Is it OK to pressure-wash decorative concrete?
Sparingly, and only on low setting. Pressure washers can strip the sealer in a single pass. We recommend a soft brush + garden hose for routine cleaning.
Does winter rain damage concrete?
Rain itself doesn't damage decorative concrete — but standing water does, and salt-laden rain near the coast does. The fix is good drainage + a quick hose-rinse after storms.