When a new drawing revision shows up, you need to know exactly what changed. Here's the problem: revision clouds don't tell the whole story. Designers sometimes forget to mark changes, and even small modifications can have big downstream effects. This guide shows you how to systematically compare revisions so nothing gets missed.

Step 1: Make Sure You Have the Right Versions

Before you start comparing, double-check that you're looking at the correct revisions:

Check the revision block in the title block and note the revision number and date

Verify that file names match your expected naming conventions

Confirm both sets are complete with the same number of sheets

Note any sheets that were added or removed between revisions

Step 2: Start with the Revision Clouds

Look at the marked changes first, but don't stop there:

Find all revision clouds on each sheet

They should reference the revision number in the title block

Read the revision description in the title block

This should explain what changed and why

Understand the intent behind each change

Is it a design change, a coordination fix, or value engineering?

Think about whether the change affects other disciplines

A structural change might mess up MEP routing

Step 3: Use Visual Overlay Comparison

Overlay the old and new drawings to catch changes that weren't clouded:

PDF Overlay Method

1. Open both PDFs in Bluebeam, Adobe, or similar software

2. Use the "Compare Documents" or "Overlay" feature

3. Set one drawing to display in one color and the other in a contrasting color

4. Anywhere the colors don't overlap, something changed

Quick Toggle Method

1. Open both drawings in separate tabs

2. Flip back and forth quickly while looking at the same area

3. Your eye will catch the movement where lines changed

4. This works great for quick spot-checks of specific areas

Step 4: Check the Usual Suspects

Some changes almost never get clouded. Always double-check these areas:

General Notes

These get updated all the time without revision clouds

Schedules

Individual line items often change without any marking

Specification References

Section numbers get updated globally

Details

Minor dimension tweaks usually go unclouded

Abbreviation Lists

New items rarely get marked

Step 5: Think Through Downstream Impacts

Every change can ripple through the project. For each change you find, ask yourself:

Does this affect other sheets in the same discipline?

Will other disciplines need to update their drawings?

Does this impact work that's already in progress or done?

Does this change material quantities or procurement?

Will this affect the construction sequence?

Are there cost implications someone needs to know about?

Step 6: Document and Distribute

Put together a revision summary for your team:

List all changes by sheet number and location

Organize by discipline and impact level

Call out any unclouded changes you discovered

Identify which subs need to be notified

Flag changes that need RFIs or clarification

Related Guides

How to Review Construction Drawings

Complete guide to systematic drawing review.

How to Mark Up PDF Drawings

Create clear, actionable markups for coordination.

Automate Revision Comparison

Manual overlay comparison is slow and easy to mess up. Articulate's AI can automatically compare drawing revisions and highlight every change, including the ones designers forgot to cloud.

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How to Compare Drawing Revisions