CONCRETE FLATWORK: THE 72-HOUR FLATNESS CLOCK
Floor flatness and levelness are measured under ASTM E1155 as FF (short-range bumps, roughly every 2 feet) and FL (long-range slope, roughly every 10 feet), and the standard requires measurement within 72 hours of final troweling, before loading and partitions.
This page covers one problem. The full picture for this trade, including the other places margin leaks, is on the concrete flatwork operating system page.
WHERE THE MONEY GOES.
Floor flatness and levelness are measured under ASTM E1155 as FF (short-range bumps, roughly every 2 feet) and FL (long-range slope, roughly every 10 feet), and the standard requires measurement within 72 hours of final troweling, before loading and partitions. That window is the finisher's whole defense: "floor profiling after the fact, once construction activities have introduced point loads and deflections, doesn't reflect the slab as placed." Slabs also curl and change over time. A flatwork contractor who doesn't commission (and bill) the 72-hour test surrenders the dispute to whoever measures last.
THE COST, SOURCED.
ASTM E1155 72-hour requirement and dispute framing (IFTI, 2026); "overall statistics can pass while localized defects create real installation problems," so specs carry both specified-overall and minimum-local values; remediation is grinding high spots or self-leveling, and "in general, grinding a floor will only make things worse" for exposed finishes (Archtoolbox). Division 3 FF/FL testing happens at 72 hours while Division 9 flooring installs months later after curl, which is exactly the flatwork-vs-flooring liability seam.
THE NUMBER TO MEASURE IT AGAINST.
Concrete Flatwork contractors run about % net profit at $1M to $5M, rising to roughly 10% at $5M to $10M. The CFOS target at $1M to $5M is10%, set at 10 percent before taxes or 3.5 points better than your trade's average at your revenue, whichever is higher. A problem like this one lives in the distance between those two figures rather than in a loss on any single job.
Gross margin over the same bands runs % to 23%, against a CFOS target of 10%.
THE SYSTEM THAT FIXES THIS.
Cost codes built against the estimate, so a job can be read while it runs.
FREQUENTLY ASKED.
