A driveway formed for a concrete pour, with rebar raised on chairs over a compacted gravel base

Slab thickness guide

How Thick Concrete Should Be for Walks, Patios and Driveways

Four inches for a walk, five to six where cars park or turn, and six with rebar where heavy vehicles sit. Call and we will size your slab to what it has to carry.

Call for an Estimate (262) 583-6057

Free, no-obligation estimates. We answer the phone or call back the same working day.

The short answer

How thick concrete should be

A walk is usually four inches thick, a slab where vehicles park or turn is five to six inches, and a slab where heavy vehicles sit is six inches with rebar.

Thickness follows the load, not the size of the slab, and a patio is sized the same way, by what it carries. Each extra inch of driveway thickness adds almost 50% to what the slab can bear and about 20% to the material cost, so we size it to the load instead of guessing high or low.

Here is how we size a slab by what sits on it.

Concrete slab thickness by the load it carries
What it carries	Where you see it	Thickness
Feet	Walks and sidewalks	4 inches
Cars that park or turn	Driveways, garage slabs and parking pads	5 to 6 inches
Heavy vehicles that sit	Pads where a heavy truck or trailer stays parked	6 inches#4 rebar on chairs at 18 inches on center

The mix

The mix for exterior concrete

Exterior slabs take a 4,000 psi "air-entrained" mix, because outdoor concrete here has to live through freeze-thaw every winter.

The air is the part that earns its keep in our winters. Tiny bubbles through the paste give freezing water somewhere to go, so the surface holds instead of popping and flaking; the Portland Cement Association explains the science behind it.

Thickness and mix work together: the right depth in the wrong concrete still flakes and pits, and the right concrete poured too thin still breaks under the load. On a driveway the slab also needs the right drainage slope and a sealer once it has cured.

Exterior slab mix

4,000 psi

Compressive strength

Goes into: Walks, patios, driveways and other outdoor slabs
Air: Entrained, the winter-grade mix
Driveway slope: Graded so water drains off
After cure: Sealed on driveways

Reinforcement

Rebar and fiber reinforcement

Patios get fiber mixed into the concrete, and steel goes in where a slab spans backfill or carries heavy loads.

Fiber in the mix

Patios

A patio carries people, chairs and a grill rather than vehicles, so fibers through the concrete hold it together without a layer of steel.
Steel over backfill

Slabs that span filled ground

Where a slab crosses ground that was dug out and filled back in, such as along a foundation, steel carries it across the softer fill.
Steel under heavy loads

Where heavy vehicles sit

The six-inch slab gets #4 rebar on chairs at 18 inches on center, so the steel sits inside the concrete instead of on the ground under it.

Every driveway gets reinforced concrete over a compacted gravel base that drains.

Under the slab

The base under the slab

The gravel base goes as deep as the excavation shows it needs to, and clay ground calls for a thicker compacted base.

That is why nobody can give you an honest base depth over the phone. We dig to the right depth, place the base material and compact it thoroughly, and what we find in the hole decides how much stone goes back in.

Clay holds water and moves when it freezes, so it gets more compacted stone between it and the concrete. A thick slab on a thin base over clay is still a slab waiting to heave.

Call Sophisticated Concrete

Concrete slab4 to 6 inches, set by the load

Compacted gravel baseDepth set by what the dig finds

Native groundClay calls for a thicker base

Next to thickness

Neighbors on Their Driveways and Walks

Our Google reviews, as the people who left them wrote them.

Sophisticated Concrete did a fantastic job on my driveway! The team was on time and professional, completing the project exactly as promised. The quality of their work was impeccable, and they offered great prices too. I am extremely satisfied with the outcome and would highly recommend them to anyone in need of concrete services. Great work Mike I will definitely be recommended you with all friends and family’s !!

Yosi ZaragozaGoogle review

I recently had the pleasure of working with Sophisticated Concrete for my driveway and side walks, and I couldn't be happier with the results. They did an amazing job, exceeding all my expectations. The team was incredibly punctual, arriving right on time and completing everything perfectly. Not only was the workmanship top-notch, but their prices were also very reasonable. I highly recommend Sophisticated Concrete for anyone looking for high-quality concrete work. Thank you so much Mike it was a pleasure.

luke martinezGoogle review

Great work, very detailed and great price. I would recommend to anyone looking to get concrete work done!!! Great company overall.

Tyler ColonGoogle review

Planning a New Slab? Call First.

Tell us what it will carry. We come out, measure it, check the ground and write the whole estimate, thickness and base included, before anything is poured.

Call for an Estimate (262) 583-6057

Free, no-obligation estimates, and we quote the whole job before we start, with no surprise charges after.

How Thick Concrete Should Be for Walks, Patios and Driveways

How thick concrete should be

The mix for exterior concrete

Rebar and fiber reinforcement

The base under the slab

More thickness questions

Driveway width

Vapor retarders

Driveways we pour

Neighbors on Their Driveways and Walks

Planning a New Slab? Call First.