This is the question everybody asks on pour day, usually while the crew is still cleaning up. Fair enough, since your car is parked on the street until you get an answer.
The short version
| What | How long |
|---|---|
| Walk on it | 24–48 hours |
| Passenger car or small SUV | about 7 days |
| Full-size truck or work van | 10–14 days |
| RV, trailer, dumpster, loaded truck | 28 days |
| Pressure wash or seal | 28 days, and sealing often later |
Those are warm-weather numbers. A pour in late October gets different dates, and we'll give you the real ones for your job rather than the generic ones.
Why a week and not a day
Concrete doesn't dry. It cures, which is a chemical reaction between the cement and the water, and that reaction keeps going for weeks. The number you'll hear people throw around is 28-day strength, because that's the age concrete is tested at.
At seven days a typical mix has somewhere around two-thirds of its 28-day strength. That's enough for a car. It isn't enough for a loaded trailer tongue putting a few thousand pounds through a jack foot the size of a saucer.
And that's the real risk with driving on it too early. It's not that the whole slab collapses. It's point loads: a jack stand, a trailer tongue, a heavy tire parked in one spot on a hot day. Those leave you a permanent dent or a crack in a slab that would have been fine a fortnight later.
Cold weather changes everything
Concrete gains strength much more slowly as the temperature drops, and below about 40 degrees it nearly stops. A slab we pour in mid-November might need twice as long to hit the same point as one poured in July.
That's why we pour into early December with an accelerator in the mix, warm water and insulated blankets over the top, and why from about late December through February we'll tell you to wait for spring instead of taking your deposit. Two hard reasons:
- You can't compact a frozen base. And the base is the part that decides whether the slab is still flat in twenty years.
- Concrete that freezes in the first few days never gets its surface strength back. It'll look fine in March and start coming apart a couple of winters later.
The first year matters more than the first week
Here's the part people skip, and it does more damage than parking early ever does.
No ice melt on new concrete for the entire first winter. Not rock salt, not the blue stuff, not the bag that says "safe for concrete" on the front. Use sand for traction instead.
New concrete hasn't developed the surface density to shrug off chloride yet. Salt doesn't dissolve concrete directly, but it dramatically increases how many freeze-thaw cycles the surface goes through and pulls water deeper into it. On a slab in its first winter, that's how you end up with a sandy, flaking surface by year three on concrete that was poured properly.
After the first winter, keep it modest. A penetrating siloxane sealer every three to five years is cheap insurance on a driveway that sees a lot of street salt tracked onto it.
A few other first-year things
- Keep it damp the first week if it's hot. If we've left cure on it, you don't need to do anything. If it's 95 degrees and windy, a light sprinkle a couple of times a day in the first few days genuinely helps.
- Don't park in exactly the same spot every day for the first month, especially in heat.
- Expect hairline cracks and some color variation. Both are normal. Cured concrete keeps changing tone for a couple of years, so a new slab next to an old one will look mismatched at first and then close up a lot.
- Leave the joints alone. If a crack shows up along a saw cut, that's not a failure. That's the joint doing its job.
Quick answers
Can I park on it after 3 days if I'm careful?
We'd rather you didn't. At three days a warm-weather pour is still well short of where it needs to be, and the damage from going early isn't dramatic, it's a dent or a crack in one spot that you then live with. If you're stuck, tell us when we schedule and we'll talk about where to leave a section accessible or how to sequence the pour.
How long before I can seal it?
At least 28 days, and often longer. Concrete needs to release moisture before a sealer goes on, and sealing too early can trap water under the film and cause it to blush or peel. For a brand new slab we'd generally wait until the following spring, after it's been through a winter.
Does rain right after the pour ruin it?
Light rain a few hours after finishing is usually fine and sometimes helps the cure. Heavy rain while the surface is still soft can wash the paste off the top and leave it weak and pitted, which is why we watch the forecast and will move a pour rather than gamble. If it rains hard on a fresh pour, tell us and we'll come look.
Got concrete that needs work?
Tell us what you're looking at and we'll tell you what it needs, what it costs, and when we could get to it.