Top Mistakes to Avoid When Preparing As-Built Drawings

As-built drawings are essential documents in any construction project. They show the final, built condition of a structure and capture any changes made during construction that differ from the original design. Contractors, architects, engineers, and even facility managers rely on these drawings to understand exactly what was built.

But preparing as-built drawings is not just about marking changes. It requires attention to detail, accuracy, and proper documentation. Mistakes can lead to confusion, rework, delays, and safety risks in the future.

In this article, we’ll go over the top mistakes people make when creating as-built drawings and how to avoid them. Whether you’re drafting by hand, using CAD, or working in BIM, these tips will help you deliver high-quality, reliable as-built drawings every time.

1. Not Capturing All Changes During Construction

One of the most common mistakes is failing to document every change made on-site. Construction projects often face unexpected changes like pipe rerouting, material substitutions, or layout adjustments. If those updates are not recorded in the as-built drawings, the final documents become incomplete or misleading.

How to avoid this:

• Communicate regularly with the site team to track changes as they happen.
• Keep a running log or markup set of field modifications.
• Do not rely on memory. Always measure and verify before updating the drawing.

2. Using Old or Incorrect References

Sometimes, drafters use outdated plans or incorrect versions of architectural or structural drawings as their starting point. This results in as-built drawings that do not match the final built conditions.

How to avoid this:

• Always confirm that you are working with the latest approved set of construction drawings.
• Coordinate with the project manager or lead architect before starting.
• Clearly label your files and drawing sets to prevent confusion.

3. Inaccurate Field Measurements

As-built drawings depend on precise field measurements. If those measurements are even a few inches off, it can affect future installations, inspections, or renovations.

Common causes of bad measurements:

• Rushing during site visits
• Using the wrong tools or techniques
• Measuring from unverified or movable surfaces

How to avoid this:

• Use digital tools like laser distos or total stations for accuracy.
• Double-check key dimensions with a second person or tape.
• Always measure from fixed reference points like walls or columns.

4. Missing Key Elements

Another issue is leaving out important details like plumbing runs, electrical outlets, HVAC ducts, or wall thicknesses. These may seem minor at the moment, but missing them can create big problems later.

How to avoid this:

• Follow a checklist during site walks to make sure nothing is overlooked.
• Take photos as references while you’re on-site.
• Ask engineers or subcontractors what must be shown in the final drawing.

5. Cluttered or Unclear Drawings

As-built drawings need to be easy to read. If they are cluttered with overlapping lines, unclear notes, or messy dimensions, the drawings lose their value.

How to avoid this:

• Use proper layering in your CAD or BIM software.
• Keep line weights, text sizes, and hatching consistent.
• Add clear legends, callouts, and labels where needed.

Less is often more. Include enough information to be useful, but do not overload the drawing.

6. Poor Version Control

If multiple people are working on the drawings or there are several revisions, things can get messy fast. Using the wrong version of a file can result in lost work, duplicated efforts, or conflicting details.

How to avoid this:

• Use a clear naming system for files, such as “ProjectName_AsBuilt_v03.dwg”
• Maintain a revision log that tracks updates, dates, and who made changes.
• Consider using version control tools or shared cloud platforms to manage updates.

7. Not Following Drafting Standards

Different projects and clients may require different drawing standards, including line types, symbols, layers, and title blocks. Ignoring these standards can lead to rework or rejected submissions.

How to avoid this:

• Ask the client for their drawing standard or CAD template before starting.
• Use standard architectural symbols and notation.
• Make sure units, scales, and sheet layouts match the client’s expectations.

8. Lack of On-Site Coordination

Sometimes, drafters create as-built drawings without spending enough time at the construction site. This leads to assumptions, and assumptions can be wrong.

How to avoid this:

• Visit the site in person if possible.
• Coordinate with the site supervisor or foreman to walk through the building.
• If working remotely, ask for detailed photos, markups, or scans from someone on-site.

The more information you gather from the field, the more accurate your drawings will be.

9. Skipping Quality Checks

Even experienced drafters make mistakes. A missed label, wrong dimension, or misplaced door can sneak into a drawing. If no one checks the work before submission, it can result in costly errors or delays.

How to avoid this:

• Always do a final review of your drawings before submitting.
• Use checklists to catch common issues.
• If possible, ask a second person to do a peer review.

A fresh set of eyes can often catch things you have missed.

10. Forgetting to Archive Source Data

Photos, notes, sketches, and markups are all part of the as-built process. If you do not keep these organized, you may struggle to explain or verify decisions later.

How to avoid this:

• Store all source data in one organized folder.
• Name files clearly by date and location, such as “SouthWall_OutletPhoto_March2025.jpg”
• Use cloud storage or project management tools to keep everything backed up.

Final Thoughts

As-built drawings are more than just documents. They are records of reality. They show what was actually built, how it was built, and where everything is located. A good as-built drawing saves time, avoids confusion, and builds trust with clients and project partners.

Avoiding the mistakes we’ve covered, like inaccurate measurements, missing changes, poor file control, and unclear drawings, can make your as-built work more reliable and professional.

At the end of the day, it’s about being thorough, organized, and committed to getting the details right. Your future self and your clients will appreciate the effort.