Can you lay a resin driveway over existing concrete?

It's one of the most common questions we're asked in Geelong: "I've got an old concrete driveway — can you just lay resin over the top?" Overlaying existing concrete is genuinely one of the best things about resin-bound stone. There's often no need to break out and cart away a perfectly serviceable slab, which saves you money, days of mess, and a skip-bin's worth of landfill. But — and it's an honest "but" — it only works when the concrete underneath is up to the job. Here's exactly how we decide.

Is your existing concrete actually suitable?

A resin-bound surface is only ever as good as what it sits on. We trowel a beautiful, seamless finish — but if the slab beneath it moves, cracks or stays damp, that finish will eventually tell the story. So before we quote an overlay, we run a few straightforward checks at your free site assessment. Three things matter most.

• 1. It's structurally sound

  The slab carries the load — resin-bound stone doesn't add structural strength. We look for a stable base that doesn't rock, drum or flex underfoot, with no significant settlement, heave or crumbling. Sound, hairline-cracked concrete is usually fine; concrete that's lifting, sinking or breaking up is not.

• 2. It's fully cured

  Resin won't bond reliably to "green" concrete that's still releasing moisture. A freshly poured slab needs roughly three to four weeks minimum to cure before we'll overlay it — and we confirm it with a moisture test rather than guessing off the calendar.

• 3. It's dry & clean

  The aliphatic polyurethane binder needs a dry, contaminant-free surface to grip. Trapped moisture, old sealers, paint, oil stains or curing membranes all interfere with the bond, so the slab is cleaned and prepared, and laid in suitable weather.

About that moisture test

This is the step a lot of cheaper quotes skip — and it's the one that quietly causes failures down the track. Concrete can look bone-dry on top while still holding moisture deep in the slab, especially a newer pour or one over damp ground. If that moisture has nowhere to go, it pushes up against the resin film and undermines the bond.

So for any slab that's new, recently laid, or that we have doubts about, we carry out a moisture check before committing to an overlay. New pours get the full ~3–4 week cure window plus a test — not one or the other. It's a small step that protects a 5-year guarantee, so we don't treat it as optional.

How cracks and movement joints are handled

Here's a principle worth understanding before anyone quotes you: a resin overlay doesn't make existing cracks or joints disappear. It manages them honestly. Concrete moves — it expands in summer heat and contracts in the cold, and it has deliberate control and expansion joints built in precisely so that movement happens where it's planned rather than at random.

Trowelling a thin, rigid skin straight across those lines and pretending they aren't there is exactly how an overlay fails. The slab moves, the movement has to go somewhere, and a buried joint will telegraph straight back through the new surface as a crack. So we don't bury them — we work with them.

Existing cracks

• Static hairline cracks in an otherwise sound slab are typically cleaned out and filled with an appropriate flexible repair before the wear course goes down.
• Active or working cracks — ones that open and close as the slab moves — are a different matter. These tell us the slab is still moving, and that movement needs to be either accommodated with a managed joint or addressed at the base.
• Widespread or structural cracking is a sign the slab itself may be past overlaying — see when to replace it below.

Movement & expansion joints

Existing expansion and control joints are honoured, not buried. The standard practice is to carry the joint up through the new resin-bound surface so the two layers move together. It's a small detail that keeps the finish looking deliberate and, more importantly, stops the slab's natural movement from tearing the surface apart. If your concrete has joints in it now, expect to see those lines reflected — by design — in the finished resin.

Profiling: keying a smooth slab so resin grips

A brand-new, power-floated concrete slab can be almost glassy — and resin struggles to grip a polished surface. "Profiling" (you'll also hear it called keying, abrading or mechanically preparing the slab) simply means roughening that smooth face slightly so the binder has texture to bond into. Think of it like keying a wall before you paint it.

Depending on the slab, this is done by grinding, shot-blasting or scarifying the surface, then thoroughly removing all the dust so we're laying onto clean, sound concrete. A well-profiled slab is the difference between a wear course that's genuinely bonded for the long haul and one that's relying on luck.

When the concrete should be replaced instead

We'd rather lose a sale than lay a premium surface over a base that's going to let you down. An overlay saves real money — but only when the slab deserves it. There are times when the right, honest answer is to repair the base properly or start again. We'll tell you if your driveway is one of them.

An overlay generally isn't the right call when the slab is:

• Structurally failing — lifting, sinking, rocking, drumming when you walk on it, or breaking into pieces. No surface finish fixes a slab that's come apart.
• Heavily or actively cracked — widespread cracks, or cracks that are clearly still moving, mean the movement will reflect through almost any overlay.
• Suffering from rising damp or persistent moisture that a moisture test confirms and that can't be resolved — the bond won't hold.
• The wrong fall, or badly ponding — if water pools on the existing slab, that won't change under a non-permeable overlay, so the fall may need correcting first.

In some of these cases a localised repair, a bonded screed, or building a fresh permeable base is the better route — and if you want drainage rather than a sealed surface, a new permeable build-up is the only way to get there. We assess all of this on site and put the genuinely right approach in your written quote, not just the cheapest one.

So — should you overlay your concrete?

For a great many Geelong driveways, overlaying sound existing concrete with resin-bound stone is a smart, cost-effective upgrade: a seamless, UV-stable, low-maintenance surface, no demolition, and far less waste — all backed by our 5-year written workmanship guarantee. The keys are an honest assessment of the slab, respecting its cracks and joints rather than hiding them, profiling a smooth surface properly, and being clear that over solid concrete the result is durable but not permeable.

If you'd like to know whether your slab is a good candidate, the best next step is a free site visit. You can also get a rough figure first with our instant estimate tool, see the look across our resin driveways service page, or dig into the wider topic in our resin driveways in Geelong guide and the cost guide.