Sealing a driveway is one of those jobs that gets sold as essential and is frequently not. It is worth doing on some surfaces in some locations, and on others it is money spent to create a future maintenance liability.
Here is how to tell which situation you are in.
What sealing actually buys you
Three things, in order of how much they matter.
Resistance to staining. Unsealed concrete is porous. Oil, rust, leaf tannin and tyre rubber soak in rather than sitting on top. A sealed slab gives you time to clean a spill before it becomes permanent, which on a light-coloured or decorative driveway is the main argument.
Protection from salt and water ingress. This is the real one in coastal Sydney. Water carrying chloride into concrete is what drives both surface scaling and, over a long enough period, corrosion of any reinforcement. Further from the coast it matters considerably less.
Appearance. A film-forming sealer deepens colour and adds gloss. On exposed aggregate or coloured concrete this is often the actual motivation, and there is nothing wrong with that as long as you know you are buying a cosmetic finish with a service life.
When not to bother
Plain grey structural concrete, inland, in reasonable condition, with no decorative finish and no particular staining risk, does not need sealing. It will be fine unsealed for decades. Anyone telling you otherwise is selling.
A driveway that is already badly stained should not be sealed until the stains are out. Sealing over a stain makes it permanent and removes your options — the stain is now under a coating.
A slab with structural cracking or scaling needs assessment, not a coating over the top.
And new concrete needs to cure first. Generally 28 days minimum, and longer before a penetrating sealer will take properly.
Which product for which driveway
The fundamental choice is between a sealer that forms a film on the surface and one that penetrates into it. We cover the full range in choosing a concrete sealer, but for driveways specifically:
Plain concrete, coastal. Silane-siloxane penetrating sealer. It defends against salt and water, which is the actual threat, and it has no cosmetic failure mode. Five to ten years. It will not change how the driveway looks, which is the trade-off people find hardest to accept.
Exposed aggregate. Solvent-based acrylic if you want the stones to pop, water-based if you want something subtler. Expect to recoat every two to three years, and budget for that at the outset rather than being surprised by it.
Stencilled, stamped or coloured concrete. Acrylic. The decorative finish is the whole point and it needs the film to stay vivid.
Brick or concrete pavers. A penetrating sealer, plus consideration of whether you want the jointing sand stabilised at the same time. Film sealers on pavers tend to look wrong and trap moisture in the joints.
Heavily trafficked or commercial. Polyurethane, for the abrasion resistance.
Wet look, and the thing to know about it
The wet-look finish that makes exposed aggregate look permanently just-rained-on is achieved with a solvent-based acrylic, usually at a higher build.
Two things people are not always told. It is slippery when wet, which matters on a sloped driveway and matters a lot around a pool. And it is the finish most likely to go white or cloudy if there was any moisture in the slab at application, or if water later gets underneath the film.
That blushing is not a stain and cannot be cleaned off. It is moisture trapped under the coating, and fixing it means stripping the sealer and starting again.
Where it goes wrong
Almost every failed driveway seal we are asked to look at comes down to one of four things.
The slab was not clean enough. Residual oil, tyre rubber, efflorescence or organic growth gives the sealer nowhere to bond, and the coating peels in patches. Oil stains in particular need proper treatment rather than a wash.
The slab was not dry. Sydney humidity and a tight timeline is a bad combination. Most products want several genuinely dry days after washing.
It was applied too thick. Two thin coats outperform one heavy coat on every film-forming product. A thick coat traps solvent, stays soft, and marks under tyres.
It was done in the wrong conditions. Direct summer sun on a hot slab flashes solvent off before the product levels, leaving lap marks.
There is also a timing issue specific to driveways: a car parked on a freshly sealed acrylic surface before it has fully hardened leaves tyre prints that do not come out. Most products want a few days before vehicle traffic, and in warm weather longer, not shorter.
How often
Acrylic on a Sydney driveway in full sun: two to three years, realistically closer to two on a north or west-facing slab.
Penetrating silane-siloxane: five to ten, and you test it by seeing whether water still beads.
Polyurethane: five to ten, but recoating needs proper preparation rather than a wash.
The simple test for any of them is to pour a cup of water on the driveway. If it beads and sits, the sealer is working. If it darkens the concrete and soaks in, it has gone.
Getting it done
If you want the slab cleaned and sealed properly, including stain removal first and the right product for the surface, that is driveway sealing, and the cleaning that has to happen first is driveway cleaning.
And if the honest answer for your driveway is that it does not need sealing, we will tell you that instead.
