Concrete flatwork FAQ: scope, cost, and specs

Last updated: October 1, 2026

What does flatwork cover, what does it cost, how thick should the slab be, and which cracks are normal? This concrete flatwork FAQ answers the questions our crews field on almost every pour. Flatwork is roughly 80 percent of the concrete a homeowner ever buys, so most people asking are asking for the first and only time. We answer each one straight, dollars and all, because standard flatwork runs $5.32 to $15.61 per square foot and guessing at that number is how a budget goes sideways before the first truck shows up.

What flatwork covers

Flatwork covers most of the concrete a buyer ever orders, roughly 80 percent of it. Three answers sort the category out.

What is concrete flatwork?

Concrete flatwork is any horizontal pour finished level or at a controlled slope. Driveways, patios, sidewalks, garage aprons, slabs, and building pads all count. If you walk on it or drive on it and it sits flat on the ground, it’s flatwork. The word separates these ground-level pours from vertical work like walls and footings, and one shared set of rules governs all of it, whether the pour is a 100 square foot stoop or a 20,000 square foot warehouse floor. See our concrete flatwork guide for the full breakdown.

What projects fall under concrete flatwork?

Flatwork covers a wide range. The common project types:

• Driveways, residential and commercial
• Patios, stoops, and porches
• Sidewalks and walkways
• Garage, shop, and interior slabs
• Equipment and RV pads
• Warehouse, retail, and distribution center floors

Residential flatwork is the bulk of what a homeowner buys. Commercial flatwork, the spec-grade end of the category, lives on our commercial flatwork page.

What is the difference between residential and commercial flatwork?

The difference is the spec. A residential crew pours to a thickness and a finish. Commercial flatwork answers to a structural specification with measured flatness tolerances, heavier reinforcement sized to rack and forklift loads, and a paper trail that follows the slab from subgrade compaction through the final profiler readout. From the curb the two can look identical, because a gray slab is a gray slab. Underneath, the load requirements, flatness numbers, and finish compatibility set them apart, and only one of the two gets checked with a Dipstick profiler before anybody signs off on it.

Cost and value

Cost is the first question on almost every call. Here’s how the number actually builds.

How much does concrete flatwork cost per square foot?

Standard broom-finished concrete flatwork runs $5.32 to $15.61 per square foot installed. Sidewalks sit near the low end, patios run $5.30 to $17.72, and stamped or exposed-aggregate finishes climb toward the top. Commercial spec-grade slabs start at $6.19 per square foot, depending on thickness and the flatness target. Where you land inside that band comes down to thickness, reinforcement, finish, demolition, and how much square footage there is to spread the fixed mobilization cost across. Our concrete cost guide breaks down every line.

Why does flatwork pricing vary so much?

Flatwork pricing varies because five variables move almost every number across a $5.32 to $15.61 per square foot band. Thickness sets the ready-mix volume. Reinforcement decides whether the slab holds together when the ground shifts. Finish controls how many labor hours the surface eats, and it swings the widest of the five. A broom-finished patio and a stamped patio of identical size pour the same slab underneath; the entire price gap sits in surface labor and decorative material, not concrete. Demolition, site access, and total square footage move the rest.

Is a thicker slab worth the extra cost?

Usually, yes. Moving from 4 inches to 5 or 6 inches costs more per square foot because the deeper pour pulls in 25 to 50 percent more ready-mix, but slab strength scales with the square of thickness, not straight-line with it, so a small jump in inches buys an outsized jump in load capacity. A 4-inch driveway under a loaded one-ton truck cracks where a 5-inch slab holds. Nobody goes back and adds an inch after the truck leaves, so thickness is a decision you get one shot at.

Slab thickness and mix design

What rolls across the slab sets the recipe, not the size of the pour.

How thick should a concrete driveway be?

A residential driveway carrying cars and light trucks needs 4 inches of concrete over a compacted base. Go heavier for heavier loads. For RVs, work trucks, or any vehicle over 8,000 pounds, step up to 5 or 6 inches, and add a #4 rebar grid while you’re at it. Patios and sidewalks that only carry foot traffic are fine at 4 inches under ACI 332, the residential code that treats 4 inches as the floor for slabs-on-grade.

What concrete mix do you use for flatwork?

Mix follows the load. Residential walkways run fine on a 3,000 to 3,500 psi mix, driveways carrying vehicles want 4,000 to 4,500 psi, and commercial slabs use a minimum 4,000 psi mix with three-quarter-inch aggregate. For slabs that will be polished or coated, we keep the water-to-cement ratio below 0.45 so the surface densifies properly later. Watch the water at the truck. A mix watered down on site to make it easier to place is the most common way a strong spec becomes a weak finished slab.

Do you need a vapor barrier under a slab?

A vapor barrier belongs under any slab inside a conditioned space or under a floor covering. The 10 to 15 mil polyethylene sheet blocks ground moisture from migrating up through the concrete, which is what causes coating failures, efflorescence, and that musty smell in a finished garage. Exterior driveways and open patios generally skip it because the surface breathes and dries to open air. The call turns on what goes on top of the slab and whether walls enclose the space.

On a slab that is already poured, the honest answer is that nobody can see it from the top. The sheet is under the concrete, the crew that placed it moved on years ago, and the paperwork almost never survives the build. So we read the floor instead of the file. White powdery efflorescence, dark patches that get darker after a wet week, a musty smell in a closed garage, or an old coating that peeled off in sheets all point the same direction. Taping a square of plastic down overnight is a hint, not a verdict, so before we commit a coating to a slab with no barrier we can confirm, we run a moisture test on the concrete itself and let that reading decide what goes on top.

Pouring, finishing, and curing

The pour everyone watches is the short part. The base and the cure decide the outcome, and the rest of the build has to work around both.

What happens during a flatwork pour?

A flatwork pour runs six stages: subgrade preparation and compaction, base and reinforcement placement, concrete placement, finishing, joint sawcutting, and curing. The order is fixed. Everybody watches the troweling because it’s the part that looks like the finished product, and it isn’t the part that decides anything. The base and the first week of curing decide whether the slab lasts. That finishing pass is the last 10 minutes of a job that’s mostly dirt work, crushed aggregate, steel placement, and timing, and a broom finish over a soft, uncompacted subgrade cracks and settles inside two winters no matter how clean the surface looked on day one.

How long does concrete flatwork take to cure?

Concrete reaches roughly 70 percent of its design strength in 7 days and approaches full strength near 28 days. You can walk on most flatwork after 24 to 48 hours and drive light vehicles after 7 days, but the chemistry only completes if the slab stays wet through that first week. A proper 7-day moist cure, or a cure-and-seal membrane sprayed on right after finishing, raises final surface strength and abrasion resistance by 30 to 50 percent against a slab left to air-dry in the sun.

What finish options are available for flatwork?

The finish sets both the look and the traction, and it has to match where the slab lives. The common choices:

• Broom finish: dragged across the floated surface for slip resistance on exterior driveways, patios, and sidewalks.
• Exposed aggregate: the top paste washes off to reveal the stone for a high-traction patio.
• Stamped concrete: textured mats pressed into the wet slab to mimic stone, brick, or plank.
• Steel-trowel: a smooth interior finish, the starting point for polishing or coating.

Match the finish to the use. A surface troweled smooth outdoors turns into a skating rink in the rain, and a broom finish indoors fights the clean look a polished or coated floor wants.

Joints and crack control

Concrete cracks. Good flatwork decides where.

Why does new concrete crack?

Some cracking is built into how concrete behaves, and it isn’t a sign anybody did the job wrong. The slab shrinks as it cures, and control joints get cut to steer that shrinkage into straight lines instead of random cracks, so a hairline crack at or running into a joint is working exactly as designed, same as a zipper doing its job. The cracks that signal a real problem look different: wider than a quarter inch, offset vertically so one side sits higher than the other, or curving in a way that ignores the joints entirely. Those almost always trace back to the base. Poor compaction, no drainage, or expansive clay lifting the slab.

Where do control joints go and when are they cut?

Control joints space at 2 to 3 times the slab thickness in feet, so a 4-inch slab gets joints every 8 to 12 feet and a 6-inch slab every 12 to 18 feet, with the saw reaching one quarter of the slab depth. Timing is the part rushed crews get wrong. Sawcut joints go in within 6 to 12 hours of finishing, early enough to control the crack before shrinkage stress builds and late enough that the saw doesn’t ravel the edges. Commercial pours follow the column-line grid per ACI 302.1R, and on a large pour the saw starts while finishing is still running on the far end.

Flatness and commercial specs

Commercial floors live or die on measured numbers, not eyeballed flatness.

What flatness specs can you hit on commercial flatwork?

Standard commercial flatwork meets ACI 117 FF 35 minimum, and higher tolerances are available on demand. Floors that will receive polished or coated finishes pour to FF 50 or higher, verified with a Dipstick profiler at 72 hours, and high-tolerance applications like VNA warehouses and automated storage can reach FF 50/FL 30 or above with supplemental screeding and re-straightening. On commercial work the FF and FL numbers are the spec, not a suggestion. A slab either hits its number or it doesn’t, and the profiler readout says which.

Why does the pour spec matter for the finish?

The pour specification determines whether the finish succeeds, and on a polished or coated floor that carries further than most buyers expect, because the slab is the floor. There is no covering to pull up and swap out when you change your mind, so “we can always change the flooring later” quietly stops being true the day the concrete is placed. A slab poured for carpet or tile never got a flatness target worth measuring and very likely got an acrylic cure film sprayed across it, and both of those get corrected later on somebody’s dime: 10 points under an FF target buys 2 to 3 extra grinding passes, and the cure film has to be mechanically removed before a coating will bond to anything.

New concrete does not settle the question either. A brand-new pour can be clean, flat to the eye, and still have been placed for a floor covering nobody is going to install, which is the most common way a fresh slab turns into a grinding bill. Our Pour-4-Polish specification exists to close that gap, which is why we ask what’s going on top before the first truck arrives instead of after the concrete sets.

Can our other trades keep working while you are on the floor?

Usually yes, as long as the floor itself stays ours. Grinding and polishing throw dust and run loud, so anyone who needs quiet or clean air works another zone that day, and freshly placed concrete is off limits to everybody until it takes weight. Coating is the strict case. Once primer or a base coat goes down, that section belongs to our crew until it cures, because a bootprint in a wet coat is a redo and not a touch up, and the redo costs the schedule more than the wait ever would. On an occupied building we stage the work in sections so the place keeps running while one area sits closed, and on a new build we would rather have a clean floor for two days than share it for five. Send us the trades you cannot move and we will sequence around them.

How do we protect the floor for the rest of the build?

Cover it, and cover it with something that breathes. Hardboard or heavy protective paper, seams taped to each other and never taped down to the floor, carries a finished slab through the punch list, because adhesive on a coated or polished surface can lift color or leave a mark when it comes back up. Sheet plastic laid flat is the common mistake: it traps moisture against the concrete and can leave a haze or a stain that has to be ground off later. Everything after that is housekeeping. Keep steel wheels, pipe cutting, and drywall mud off the covering, park nothing heavy on a bare point load, and wipe spills the day they land instead of the week somebody notices them. The floor goes in late for good reason, but there is always one more punch item, so put the covering in the schedule rather than improvising it out of leftover cardboard the morning the painters show up.

Can you coordinate with our GC on a commercial build?

Yes. About half of our commercial work comes through GC partnerships, and it helps to know we show up at two separate points in your schedule rather than one. The slab pour sits with the structural work, early, while the site is still open enough to get trucks and screeds onto the pad. The finish work is a late trade: it waits until the building is dried in, the roof is on and the wet trades overhead are done, and it goes in ahead of trim, base, and final fixtures so nothing gets dripped, cut, or dragged across a finished floor.

We provide a pre-pour submittal package with mix design, joint layout drawing, reinforcement plan, and FF/FL target specs, then carry our own insurance, keep daily logs, and meet commercial documentation requirements including safety plans and workmanship warranty certificates for the completed work. A coordination meeting before a large pour, the kind ACI 302.1R calls for, catches more problems on paper than on the slab, and we recommend it for any pour above 5,000 square feet. Crews are typically three to six weeks booked, so the useful time to call is when the sequence firms up, not the week the slab is ready for us.

Getting started with Bel Covo

The last questions cover scope, coverage, and the workmanship warranty on the work.

Can you pour the slab and finish it in one job?

Yes, and it’s almost always the cheaper path. Running the pour and the finish under one scope removes a second mobilization charge, the scheduling risk of lining up two contractors, and the finger-pointing when a rough surface or a missing vapor barrier becomes the finisher’s problem. Our Pour-4-Polish process pours the slab to spec and refines it to the finished surface under one workmanship warranty on the work, so the slab is engineered from the start to receive whatever finish you choose.

Do you offer a warranty on concrete flatwork?

Yes. Bel Covo backs flatwork with a workmanship warranty on the work itself. The coverage is on our pour and finish, not on slab movement we trace to a base or drainage problem and flag before the job, and the terms show up in the quote, in writing, so you know what’s covered before any concrete is placed. Have any contractor you’re considering, us included, walk you through the warranty terms line by line before you sign.

How do I get a quote for concrete flatwork?

Get your price in about 2 minutes through the online quote tool, or send a few photos and the dimensions. A real quote needs five facts: square footage, thickness, reinforcement, finish, and whether anything has to come out first. We return a range built on actual installed data, with no callback wait and no pressure. When the same crew pours the slab and finishes it, one quote covers both. Measure it once, and we’ll tell you what it actually takes.