How to build a winning concrete flatwork bid

Concrete flatwork looks like a simple bid until you've lost margin on a few. Square feet times unit price feels like the whole equation, and then you're three weeks into the job watching labor hours run 30% over and wondering why.

The contractors who consistently make money on flatwork have a more granular bid model than "SF × $/SF." Below is the line-item structure that catches the costs that actually move margin, broken into the categories worth bidding separately.

The four cost legs of a flatwork bid

Every flatwork line item should price out four legs:

1. Concrete material: Yards required, mix design, delivery, pump if needed, waste factor
2. Labor: Placement crew, finish crew, hand work, joint sawing
3. Forming and reinforcement: Formwork, expansion joints, dowels, mesh or rebar
4. Site prep and finishing: Sub-base prep, vapor barrier, curing compound, joint sealant

Bidding flatwork as a single $/SF number bundles all four into a black box. When the job runs over, you can't tell which leg blew up. When the bid wins below market, you can't tell which leg you under-priced.

Square-foot measurement: the easy part you can still get wrong

The takeoff itself is straightforward. Area in square feet. The mistakes come from:

• Forgetting curb returns and isolation strips. A walk that goes around a building footprint includes the corner radii. Measuring rectangle-by-rectangle without subtracting overlaps double-counts the corners.
• Using nominal vs actual dimensions. A "5-foot walk" is sometimes 4'-10" wide once you account for tolerances. On a long run, that 2-inch difference is a meaningful SF reduction.
• Ignoring thickness variation. A 4" walk and a 6" drive both bid as flatwork SF, but the concrete yards per SF differ by 50%. Take off thickness as a separate column on every line.

Cleanest takeoff structure: SF × thickness × mix grade. That gives you yards (volume) and SF (formwork/finishing) on the same row.

Mix design pricing: the spread you didn't see coming

Most contractors anchor on a "3,000 PSI mix" as their default and quote everything off it. Real flatwork bids reference 5–8 different mixes, each with a different price:

• Sidewalk mix. 3,000 to 3,500 PSI, often air-entrained in cold climates
• Drive/parking mix. 4,000 to 4,500 PSI, sometimes with fiber reinforcement
• Heavy-duty pavement. 4,500 to 5,000 PSI for truck routes or industrial applications
• Decorative mix: Colored, integral pigment, or stamped concrete with admix charges
• Fast-track mix: High early-strength for applications needing 24-hour traffic
• Warm-weather or cold-weather adjustments: Retarder or accelerator admixtures

The unit price spread between mixes can be 25–40%. Quoting all flatwork at the cheapest mix and discovering at submittal that the spec calls for the highest mix is a classic margin compression.

The other mix-related miss: shrinkage and waste. Concrete plants charge for ordered yards, not delivered yards. A typical waste factor is 5–10% depending on placement complexity. On a $50K concrete order, that's $2,500–$5,000 you have to absorb if you didn't price it.

Finish-type variation: where labor lives

Finish type drives labor productivity more than any other variable. Same SF, same thickness, same mix can have a 2× labor cost difference depending on finish.

Rough productivity ranges (varies by region and crew):

• Broom finish: Fastest, baseline productivity
• Trowel finish (machine). 1.3–1.5× the labor of broom
• Hand-trowel finish. 1.8–2.5× the labor of broom (used for tight spaces or premium finishes)
• Stamped or textured. 2.5–4× the labor of broom, plus the stamping form rental
• Exposed aggregate. 1.5–2× the labor of broom, plus the surface retarder and washing
• Salt finish, rock-salt, or sand-blast: Varies widely; price per project

Bidding all finishes at the broom rate is the most common flatwork miss. The job comes back with a "trowel finish in lobby, stamped at entry" spec and the labor budget is suddenly 60% short.

Joint and reinforcement: the line items that disappear

Two cost categories that consistently get under-priced:

Joints. Saw-cut control joints, tooled control joints, isolation joints, expansion joints, dowel-bar baskets, and joint filler/sealant are all separate cost items. On a typical drive-and-walk job, joints run 10–18% of the total flatwork cost. Bidding them at 5% (or rolling them into the SF unit price) underprices the bid by 5–13%.

Reinforcement. Wire mesh, rebar, fiber additives, and dowels each have different material costs and labor productivity. A walk with #4 rebar at 18" o.c. each way is a different bid than the same walk with mesh. The rebar is 3–5× the cost. Specifying which reinforcement type goes where should be on the takeoff sheet, not in the assumptions tab.

Sub-base and finishing details

The two costs at the start and end of the job that often get scoped as "GC's responsibility" but somehow end up in the flatwork bid anyway:

• Sub-base prep: Fine grade tolerance, compaction, moisture conditioning, vapor barrier installation
• Curing and protection: Curing compound, blankets in cold weather, sealing/sealer if specified

Read the spec section. If sub-base is specified to ±0.05' tolerance, that's a fine-grade item, not earthwork. If curing compound is specified by manufacturer, that's a material line, not an inclusion. Move them to flatwork or get an explicit GC sign-off that they're handling it.

The hard call: subcontract or self-perform

Most grading shops do some flatwork in-house and sub out the rest. The question for each bid: which side of the line is this job on?

A useful heuristic:

• Self-perform small-to-medium walk and drive packages, typically under 5,000 SF, with broom or basic trowel finish, on jobs you're already doing the earthwork
• Sub out decorative work (stamped, exposed aggregate, integrally colored), large-volume placements over 10,000 SF, anything with a tight schedule that competes with your earthwork crew
• Build a partnership with one or two specialty flatwork subs you trust, so subbing out doesn't mean shopping every job

The mistake here is binary thinking: "we always self-perform" or "we always sub out." The right answer changes by project, and the bid model should support both options on the same takeoff sheet.

Markup is the easiest part

Once the four legs are priced out and constructability factors are applied, markup is the easiest part of the bid. A typical flatwork markup runs 15–25% depending on the market, the GC, and the competitive landscape.

The shops that consistently make money on flatwork aren't the ones with the lowest markup or the highest. They're the ones whose underlying cost numbers are the most accurate. Markup is just the layer on top. It can't fix bad costing.

If your shop is bidding flatwork at one $/SF number, the upgrade that pays back fastest is breaking it into the four cost legs above. You'll catch the under-bids before they go out, you'll have a defensible number when the GC pushes back, and you'll see exactly where margin is leaking when a job runs over.