Concrete is one of the most popular man-made construction materials on the planet, with about ten billion tons poured each year.
But while it’s the base material for structures like bridges, dams, parking garages, and traditional warehouses, it’s easy to overlook another common use:
Or what we call “concrete flatwork” in the construction industry.
From the shiny warehouse floors to the parking lot out front to the loading dock at the rear, your building is likely to have tons of flatwork in and around it.
So read on for your complete guide to concrete flooring!
What Is Concrete Flatwork?
Flatwork is a smooth, paved surface poured flat along the horizontal plane.
Everyday examples of flatwork include concrete slab sidewalks and residential driveways. In the industrial world, flatwork appears in the form of warehouse floors, parking lots, and loading docks.
At its core, flatwork is remarkably simple with just three ingredients:
- Aggregate: Sand, gravel, or crushed rock
- Cement: Binds the aggregate together when combined with water
- Water: Hardens the slab through hydration
We’ll discuss the pouring and curing process further down!
Pros and Cons of Concrete Flatwork
Flatwork is the default choice for any structure requiring a sturdy foundation — flooring, walkways, stairs, ramps, etc.
But flatwork isn’t the only option, nor is it always the best.
So before you approve your project’s schedule of values (SOV) with a row dedicated to flatwork, let’s weigh the pros and cons!
There’s a reason concrete flatwork is everywhere in our world:
Here are the most common reasons commercial companies and homeowners choose concrete flatwork:
Strength and Durability
The draw of this method is, by and large, its reliability.
Industrial-grade flatwork can withstand ~6,000 PSI of force. That’s equivalent to the weight of two Toyota Corollas condensed into a single square inch.
This strength evolves from the flatwork’s structural components. Pouring the concrete mix over a steel-reinforcing bar (rebar) increases the slab’s tensile strength to last 20–30 years.
When installed by professionals, this durable concrete can resist potholes in parking lots and avoid cracking under the weight of heavy production lines.
The Better Business Bureau lists more than 38,470 licensed concrete contractors with expertise and tools needed for large-scale flatwork jobs, like retail floors or 1,000-car lots.
Home improvement stores also stock 50-pound bags of concrete mix for smaller DIY projects, such as replacing a single slab of a walkway.
Concrete flatwork requires very little in the way of maintenance, especially with proper installation and upkeep.
Once the concrete fully cures, sealant acts as the surface’s protective shield. This invisible layer blocks the tiny holes in the concrete that typically absorb water and chemicals, causing stains.
But the inevitable industrial stains and spills don’t signal the end for flatwork, either. Yearly 3,000+ PSI power washing and resealing can keep the concrete in impeccable shape, both aesthetically and functionally.
No-frills, gray concrete slabs are standard in the construction industry. Flatwork is still semi-customizable, though.
Many concrete contractors offer add-on customizations, like:
- Troweling pigment into freshly poured concrete
- Stamping in designs or business logos
- Scoring or rolling a pattern to mimic other surfaces, like brick
- Brushing the surface to expose the rough aggregate for slip resistance
These options allow the rare opportunity to turn something as plain as concrete into a branding tool or an aesthetic touch.
Unfortunately, the integrity of flatwork is at the mercy of several factors out of your control, such as temperature changes and earth shifts.
These drawbacks may leave you second-guessing what “we’ve always done” in search of a better alternative:
Cracking and Chipping
Concrete expands with heat exposure and shrinks when ground temperatures plummet (this process is called “thermal cracking”).
Problems arise when temperature changes aren’t subtle. Unexpected heat waves after days of 50-degree weather could cause rapid expansion and, eventually, cracking. This cracking is partially avoidable with small gaps between slabs (expansion joints), as it leaves the concrete space to expand.
While cold weather typically shrinks poured concrete, winter weather can also trigger cracks via expansion. Concrete is a porous surface that absorbs water. Below-freezing temperatures could freeze this water and force expansion.
Dirt and Stains
The sealant-and-power-wash tag team is remarkably effective in reducing stain and dirt buildup in concrete flatwork. However, flatwork isn’t immune to staining in more industrial settings.
For example, spilled oil or grease in auto workshops could leave behind unsightly dark blotches. In factories and warehouses, dripped chemicals and tracked-in dirt may increase the need for cleaning.
When the ground underneath a section of poured concrete starts to shift, it’s at risk of settling, or sinking.
It’s rare, but in areas with heavy rainfall, it’s possible. Narrow gaps between the soil and concrete — either from poor preparation or burrowing rodents — gives the slab the freedom to settle.
Related: Tilt-Up Concrete Pros and Cons
Most Common Uses of Flatwork in Construction
Flatwork is one of the most reliable horizontal, flat surfaces in residential and commercial construction.
Let’s shift gears to discuss the role it plays in each industry.
Whether you’re lounging in your backyard or walking through the neighborhood, you’re never too far from flatwork.
It lines American streets in the form of sidewalks and gutters. It also appears in backyard patios and as a subfloor in basements and garages.
The most common residential uses for flatwork include:
- Pool decks
- Basement floors
- Garage floors
- Concrete patios
Poured concrete is even more common in the commercial edge of the industry. However, given its long-term durability and simple maintenance, flatwork is popular for any walkable or driveable surface.
In commercial construction, flatwork appears in:
- Parking lots
- Dumpster pads
- Garages, warehouse, and factory floors
- Sidewalks and entryway walkways
- Concrete driveways
- Loading docks
- Steps and stairs
- Office floors, when polished or stained
How Much Does Flatwork Cost?
The cost of concrete work depends on the square footage, slab thickness, prior grading, and the cost of materials. Generally speaking, a 4-6-inch-thick concrete slab could cost anywhere from $4 to $8 per square foot.
For plain concrete without any customizations, here’s what you’ll pay in the commercial edge of the industry:
|Use||Estimated Square Footage||Approximate Cost|
(One 3’ x 3’ Square)
|9 sq. ft.||$36–$72|
(50’ x 4’)
|200 sq. ft.||$800–$1,600|
(24’ x 24’)
|576 sq. ft.||$2,304–$4,608|
(100 9’ x 18’ Stalls)
|16,200 sq. ft.||$64,800–$129,600|
|Warehouse||185,000 sq. ft.||$740,000–$1,480,000|
|Department Store||250,000 sq. ft.||$1,000,000–$2,000,000|
Project prices will increase once you factor in:
- Local labor costs
- Extra thickness
- Vapor barriers or sealants
- Prep work, including grading or slab removal
- Dyes, pigments, or tints
- Stamping, patterns, or designs
- Rebar or mesh
How Long Does Flatwork Take?
Depending on its intended use, the entire flatwork process could take 24 hours to two weeks to complete.
Freshly poured sidewalks and driveways dry within 24–48 hours. By then, the slab is ready for foot traffic, though it’ll be another 5–6 days before the concrete reaches 70% of its strength.
Most 10,000 square-foot exterior projects — like parking lots or sidewalks — are ready for use within a week. So if your company is open during business hours Monday through Friday, you can schedule a sidewalk replacement for Friday afternoon and have customers safely walking on it by Monday.
It’ll be about 28 days before the concrete is fully cured, hardened, and able to support heavy machinery.
Interior flatwork projects tend to be a bit more complex, especially in large warehouses or retail pads. Factors like rebar, vapor barriers, insulation, and extra square footage could double the projected timeline.
Two weeks is more than enough time to allow the concrete to dry and support mild use. However, this may also require a bit more strategy for pre-existing offices and warehouses. Laying a new flatwork area by area is the best way to resurface the interior without shutting down operations for 28 days.
Concrete Flatwork vs. Other Alternatives
Concrete flatwork is a popular choice for large commercial spaces and areas that receive plenty of traffic, both vehicle and foot.
However, the type of project you’re planning may determine whether asphalt or pavers are better alternatives to flatwork. Below, we’ll explain how concrete flatwork compares to each.
Concrete vs. Asphalt
Asphalt is the black aggregate mixture commonly used in roads, highways, airport runways, walking trails, and parking lots.
This pavement outperforms concrete in colder climates, as it’s less likely to contract or shrink with freezing. It also runs at half the cost (about $2–$4 per square foot) and is usable within a few hours.
Like concrete, asphalt surfaces can survive 20–30 years with a protective seal coating applied every 1–3 years.
However, 18-wheelers and heavy trucks can deteriorate asphalt and cause potholes or sinking. Though functional and durable, asphalt is also plain and considered the low-end option.
Concrete vs. Pavers
Pavers are the latest landscaping craze for homeowners sprucing up their backyard or improving curb appeal with stone or brick.
This flatwork alternative is most common in residential walkways, patios, porches, and pool decks. Yet, they can also add a touch of colorful luxury outside of business as walkways and entryways.
Compared to concrete, pavers tend to be the higher-end and longer-lasting option.
It takes a team of professionals to lay each brick or stone, using polymer sands to connect them and create custom patterns. This interlocked style makes pavers easier to keep pristine, drain water, and replace individual bricks instead of an entire slab. But, the narrow gaps between each require more weeding and cleaning.
The Flatwork Process
Now that you’ve decided on flatwork over asphalt and pavers, it’s time to prepare yourself and your company for the installation process.
The steps below explain how rebar-reinforced slabs come to be:
Soil Excavation and Site Preparation
Proper site preparation is the best way to prevent the future settling, cracking, and chipping of concrete.
This means “excavating,” or clearing and flattening the ground.
The excavation process begins with a single-drum roller, which compresses the soil to ready it for a flat concrete slab. The cleared area should be deep enough to fill with a few inches of subbase (slag or gravel) to prevent natural settling and shifting in the future.
At this stage, the contractor may also lay a vapor barrier to prevent moisture and water in the subbase from soaking into the slab.
While quite viscous, concrete will flow into odd shapes without properly set boundaries. Therefore, the construction crew will use wood or plastic to create an outline for the slab as it’s being poured.
This step also ensures straight edges.
Reinforcements like rebar or welded wire mesh for interior flatwork can keep slabs together without sacrificing tensile strength. Most projects benefit from rebar positioned in a grid-like formation at about two-thirds of the height of the slab.
A ready-mix truck will pour the concrete into the mold after mixing the cement, aggregate, and water into a thick mixture. The poured concrete will then undergo the screed and trowel process to create a dense, flat surface.
Freshly poured concrete needs 28 days to dry completely as it “cures” and becomes a harder surface. The subcontractors can apply a sealant to prevent stains and water absorption when the concrete is fully cured.
Further reading: How Concrete Buildings Are Made
The pouring and curing of concrete surfaces is a standard process in commercial construction. It’ll secure a long-lasting foundation that’ll last for decades.
Looking to have flatwork poured in or around your building? Email us at firstname.lastname@example.org to get your project started!