The 10 Most Common Mistakes When Reading Blueprints (and How to Avoid Them)

Even experienced pros can misread plans. One small oversight can lead to thousands in rework. Here are the most common mistakes I see — and how you can avoid them.

1. Ignoring the Revision History

• Plans change. If you’re not looking at the latest set, you’re already behind.

2. Confusing Architectural and Engineering Scales

• Using the wrong ruler can throw every measurement off.

3. Overlooking Elevations & Sections

• Many critical details are hidden here, not on the floor plan.

4. Skipping the Legend

• Every project has its own symbol conventions — check before assuming.

5. Misreading Finish Schedules

• Wrong paint, flooring, or trim choices happen when schedules are skipped.

6. Forgetting About Mechanical/Plumbing Plans

• These affect wall penetrations, clearances, and coordination.

7. Not Cross-Referencing Detail Callouts

• That “3/A5.2” note is there for a reason — it points you to a more detailed drawing.

8. Assuming Dimensions are Always Accurate

• Some dimensions are nominal — field verify critical ones.

9. Overlooking Notes and Specifications

• Many project requirements are written in text, not drawn.

10. Not Asking Questions

• If something’s unclear, send an RFI before it becomes a change order.

Pro Tip:

A quick “plan scan” at the start of every job can catch 80% of these mistakes before they cost you.