In Plain English
Quick Answer
Any horizontal concrete surface — driveways, sidewalks, floor slabs — as opposed to walls or columns.
Definition
Definition
Horizontal concrete construction including slabs-on-grade, sidewalks, driveways, and patios, as distinguished from vertical concrete work such as walls and columns. Flatwork requires careful subgrade preparation, proper reinforcement placement, and skilled finishing to achieve flat, crack-resistant surfaces. It is among the most common types of concrete construction.
Context
Why It Matters in Bidding
Flatwork is usually bid by the square foot and is labor-intensive at the finishing stage, so estimators must account for subgrade prep, reinforcement, joint layout, and finish type, variables that swing the unit price significantly. Because horizontal slabs are highly visible and prone to cracking or unacceptable flatness, scope gaps in a flatwork bid such as omitting vapor barriers, flatness tolerances, or saw-cut joints routinely become change orders and callbacks.
Example
Example
The concrete sub's flatwork bid broke out the warehouse slab by square foot but added separate lines for the vapor barrier, wire mesh, and the specified FF/FL floor-flatness finish the spec demanded.
See Also
Related Terms
FAQ
Questions Contractors Ask
How is concrete flatwork estimated and priced?
Flatwork is measured by square foot of surface area, then priced with line items for excavation and subgrade prep, gravel base, vapor barrier, reinforcement, the concrete by cubic yard, placement, finishing labor, and saw-cut control joints. Curing, sealers, and any specified flatness tolerance also add cost, so a complete takeoff covers far more than slab area alone.
What is the difference between flatwork and vertical concrete in a bid?
Flatwork is horizontal concrete such as slabs, sidewalks, and driveways, while vertical concrete includes walls, columns, and elevated structures. Vertical work needs formwork and bracing that flatwork largely avoids, but flatwork demands far more finishing labor. Separating the two in a bid lets the estimator apply the right productivity rates and crew costs to each.
Why do floor-flatness specifications affect a flatwork bid?
Specs often require FF flatness and FL levelness numbers, and tighter tolerances demand more skilled finishers, laser screeds, and sometimes additional measurement and remediation. A superflat high-tolerance warehouse floor costs substantially more per square foot than a standard sidewalk, so estimators must read the flatness criteria carefully before applying any unit price.
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