What revision clouds are and why they matter
A revision cloud is the scalloped outline drawn around anything changed on a drawing after it was submitted. When you resubmit after plan check corrections, the reviewer doesn't re-read your whole set — they go straight to the clouds.
That's why marking changes properly speeds up approval: every cloud tells the reviewer “look here, this is where comment 4 was fixed.” An unclouded change may be missed — or cause the reviewer to re-check everything.
The three parts: cloud, delta and revision block
| Element | What it is |
|---|---|
| Revision cloud | Scalloped outline around the changed area. |
| Delta tag (Δ) | A small triangle with the revision number (Δ1, Δ2) placed next to the cloud. |
| Revision block | A table in the title block listing each revision number, date and a short description (“Plan check corrections”). |
Together they create a paper trail: the response letter says “see Δ1 on Sheet A-4,” the cloud shows exactly where, and the title block shows when.
Rules most building departments expect
- Cloud every change made in response to comments — and any other change you made, even if nobody asked for it.
- Use the same delta number for all changes in one resubmittal.
- Update the revision number and date in the title block of every revised sheet.
- Reference the cloud and delta in the response letter for each comment.
- Keep clouds tight around the change — clouding a whole sheet tells the reviewer nothing.
Check your jurisdiction's submittal standards; some have specific rules for layers, colors or whether prior-round clouds should remain.
Second and later rounds
For a second resubmittal, use a new delta number (Δ2) for the new changes. Practices vary on older clouds: many jurisdictions want previous clouds removed so only the current round is highlighted, while keeping earlier deltas in the revision block as history. When unsure, ask the permit counter.
Sheets, symbols, schedules and title blocks explained for homeowners.
Read the guideMistakes that trigger another review round
- Changing a dimension or note without clouding it.
- Clouding the change on one sheet but not on another sheet where the same element appears.
- Forgetting to update the title block date and revision number.
- Response letter pointing to the wrong sheet or detail number.
- Drawing changes that no longer match the engineer's calculations.
Tools: CAD vs. PDF
In CAD software revisions are made on the original drawing files, clouded and re-exported. If you only have PDFs, changes can still be made and clouded with PDF markup tools, though larger changes may mean redrawing part of a sheet. Our Permit Correction Service works from PDF — no CAD files needed — and delivers clouded, delta-tagged, dated sheets plus the response letter.
Frequently asked questions
What is a revision cloud on construction drawings?
A scalloped outline drawn around the part of a drawing that changed, so reviewers and builders can see exactly what was revised.
What does the delta triangle mean on plans?
The delta tag shows the revision number (Δ1, Δ2…) that a clouded change belongs to. It matches an entry in the title block revision table.
Do I need revision clouds for a permit resubmittal?
Most building departments require every change to be clouded and tagged, with the revision date updated in the title block. Check your local submittal standards.
Should I remove old clouds on the second resubmittal?
Practices vary. Many jurisdictions want only the current round clouded, with earlier revisions kept in the title block history. Ask your permit counter if unsure.
Can you cloud and revise my PDF plans?
Yes. We revise your sheets from PDF, cloud and delta-tag every change, update title blocks and write the response letter — $499 flat.