How Thick Should a Concrete Driveway Be?
Concrete Foothill Rialto answers how thick a concrete driveway should be, a question with a clear answer for a car, a clear answer for an RV and an honest disagreement in the middle.
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The slab as it starts
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The planned slab (illustration)
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The usual answers
| Use | Typical thickness | Reinforcement often used |
|---|---|---|
| Walkway | 4 in. | Wire mesh or fiber |
| Patio | 4 in. | Wire mesh, fiber or a rebar grid |
| Car driveway | 4 in.; some choose 5 in. | A rebar grid on chairs |
| RV, trailer or truck pad | 5–6 in. | A rebar grid on chairs, closer spacing |
One San Bernardino contractor's FAQ gives four inches against five to six inches with rebar, and a Los Angeles contractor's guide gives four inches as standard and five to six for RVs and heavy trucks.
Why weight matters
A slab spreads a wheel's load over the ground below it. A thicker slab spreads it wider and is stiffer, so it bends less. A motorhome puts a heavy load on a few tires, and a slab built for cars flexes under it and cracks, most often at the edges and where the wheels sit.
Where builders disagree
Some builders pour five inches for every car driveway because the extra inch is a small share of the cost. Others stay with four. Some add rebar everywhere; others use mesh or fiber for patios and walks. The disagreement is real, and a good quote says what thickness, what reinforcement and where it sits, so the buyer can weigh the choices.
What the extra inch costs
On the calculator, going from a four-inch slab with a rebar grid to a five-to-six-inch slab with rebar adds about $1 to $2 per square foot, or roughly $480 to $960 on a 480-square-foot pad, out of a total of several thousand. It is the cheapest insurance the slab offers.
Thickness is not everything
A thick slab on loose ground still cracks. The base, the compaction, the reinforcement at mid-depth, the joints and the cure matter as much. The thickness the contractor and the mix maker give is the right one for the job.
Where this leads
- Service page: RV Pads and Side-Yard Concrete — A heavier slab for an RV, trailer or side-yard access, and what to settle before it is poured.
- Local page: Concrete in Las Colinas
- All services and typical prices: Concrete in Rialto
- More illustrated guides: Concrete Guides
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