Mistakes with the documents
- Working from an old set. A newer set or an addendum replaced the sheets.
- Reading only your own discipline's sheets. Your items also show on other sheets.
- Skipping the spec. The drawings show where. The spec says what and how many accessories.
- Missing the general notes and keynotes on the first sheets.
- Missing alternates. An alternate can add or remove a whole room.
Mistakes with the count
- Wrong scale. A sheet printed or scanned at a different size. Check the scale against a known dimension.
- Counting an enlarged plan and the overall plan as two areas.
- Not multiplying typical rooms or typical floors.
- Counting only the plan when the schedule lists more. A fixture schedule or door schedule is a second count.
- Mixing units, such as linear feet and each.
Mistakes with scope
- Counting items marked existing to remain.
- Counting items marked by others, NIC or owner furnished.
- Missing accessories the spec requires with each item, such as anchors, controls or safety straps.
- Missing the difference between furnish and install.
Mistakes in the handoff
A takeoff can be right and the estimate still wrong. Numbers get retyped into a spreadsheet and a digit moves. A line gets left off the summary. Compare the takeoff total to the estimate total, line by line, before you price.
How to catch them
Use a checklist and a second person. Count from the plan, then count from the schedule, and explain any difference. Read the spec section one more time after the takeoff. An item you missed is easier to see when you know the drawings.
Bidding and estimating · Updated 11 Nov 2026