What is omission detection in construction takeoff?
Omission detection is the practice of cross-checking the independent sources of truth in a drawing set, the schedule, the plan symbols, and the legend, to catch items that one source contains and another misses. Quoting.ai Takeoff automates this as the 4 Eyes check: it counts all three sources separately and lists every disagreement for a human decision. It matters because a missed opening is not a counting error; it is installed cost, materials plus labor plus schedule impact, that the bidder eats months after the bid.
Why do hand takeoffs miss openings?
A dense multifamily set carries thousands of openings across hundreds of sheets, and the three places an opening appears do not always agree. The schedule says 214 doors, the plans show 217 symbols, the legend defines a type nobody placed. Estimators reconcile this by sampling and hope, because checking every mark against every table by hand is hours nobody bid into the job.
Estimators we work with put 70 percent of their estimating time into data entry, which is exactly the kind of attention-taxed work where a mark on sheet A-412 gets skipped at 11 PM.
How does the 4 Eyes check work?
Three counts run independently: the schedule is parsed as a table, the plan symbols are detected and tallied per sheet, and the legend's defined types are indexed. Then the counts are reconciled. Every mark in the schedule with no plan symbol, every symbol with no schedule row, and every legend type with a count mismatch becomes a listed discrepancy with sheet references.
The human resolves the list, not the whole set. That is the difference between review and re-doing the takeoff.
What does a missed opening actually cost?
The bid goes in without the opening, the contract is signed, and the miss surfaces when framing meets reality. Now the material is a rush order, the labor is unplanned, and the margin on that opening is negative before anyone argues about whose fault it was. The pitch for omission detection is not counting faster. It is never eating that cost again.
Related questions
Is omission detection the same as auto-counting?
No. Auto-counting finds symbols faster; omission detection verifies the count against the schedule and legend. A tool can count every symbol it sees and still miss the opening that only exists in the schedule.
Which trades does Quoting.ai run 4 Eyes on today?
Doors and windows, the live trades. Walls and framing are in development and early access is open.
See it on your own work
Distributors: two steps and a kickoff call. Estimators: upload a plan on a live trade. Either way, the product proves it or it does not.