To check record drawings against the as-built redlines, compare the record set with the last issued construction set so you get a list of every change the drafter made, then tick each change against the redlines in both directions: every redline should appear as a change, and every change should trace back to a redline, RFI or modification. Drawing Revision Delta produces that change list on your PC: it matches sheets by sheet number, ranks them by how much changed, clouds every change on the later set and exports a CSV you can tick off. A redline with no matching change is one that was not transferred.
This guide explains the terms, the two-way check, and where errors usually hide.
See every change between the issued set and the record set, clouded and listed.
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What is the difference between as-built drawings and record drawings?
The terms are used loosely, so it helps to anchor them to a written definition. The US federal guide specification UFGS 01 78 00, Closeout Submittals (August 2026 edition) defines them this way:
- As-built drawings are “the marked-up drawings, maintained by the Contractor on-site, that depict actual conditions and deviations from the Contract Documents.” The deviations can come from contract modifications, RFI responses, direction from the Contracting Officer, contractor design and differing site conditions. They are kept as red-lined hard copies or red-lined PDFs and serve as the basis for the record drawings.
- Record drawings are “the final compilation of actual conditions reflected in the as-built drawings.”
The same specification tells the contractor to “transfer the changes from the approved working as-built markup drawings to the original electronic CAD drawing files”, and to jointly review the markups with the as-built CAD PDFs “for accuracy and completeness”, with monthly reviews covering all sheets revised since the previous review.
Your contract may use different words; some firms call the final CAD set the as-builts. What matters is the two documents: the marked-up field set and the clean drafted set that is meant to reflect it.
Why do redlines get lost in transfer?
The transfer is manual: someone reads a marked-up sheet and edits the CAD file. Typical failures:
- A redline on a sheet nobody opened. A note on an electrical sheet about a relocated panel never reaches the drafter’s list.
- A partial transfer. The new duct route is drawn, but the dimension or the note beside it is not.
- A change carried onto one sheet but not its partner, such as a plan updated but the matching section or schedule left as issued.
- An unrequested edit. The drafter “tidies” something that was not redlined, and the record set now shows something that was never built.
The first three are omissions, so you only find them by working from the redlines. The fourth is an addition, so you only find it by working from the changes. That is why the check has to run both ways.
How do you check record drawings in both directions?
- Assemble three sets. The last issued construction set, often the conformed set; the as-built redlines, scanned or as PDFs; and the draft record set.
- Compare issued against record. Run the issued set as the earlier revision and the draft record set as the later one. The result is the list of everything the drafter changed, sheet by sheet.
- Check redlines to changes. Walk the redline set sheet by sheet. For each redline, find the matching change in the comparison. Mark it found, partial or missing.
- Check changes to redlines. Walk the change list. For each change, find the redline, RFI or modification that justifies it. Anything you cannot trace is an unrequested edit to question.
- Return the gaps. Send the drafter the missing and partial items, with sheet numbers and a snapshot of each.
- Re-compare the next draft against the previous draft, so you only review what changed since the last round.
| Finding | What it means | Action |
|---|---|---|
| Redline found as a change | Transferred | Tick it off |
| Redline with only part of the change | Partial transfer | Return with the missing part marked |
| Redline with no change | Not transferred | Return with the sheet and location |
| Change with no redline, RFI or modification | Unrequested edit | Ask for the source or a reversal |
| Sheet new or missing in the record set | Added or dropped sheet | Confirm it was intended |
Can you compare the scanned redlines directly with the record set?
You can, and it is a useful extra pass, but expect noise. Handwriting, highlighter and clouds on the redline scan are differences too, so they appear as content only in the earlier sheet. Comparing the clean issued set with the record set gives a cleaner list. Use the direct comparison as a spot check on dense sheets.
If you only have scans of the issued set, our guide to comparing a scanned drawing with a CAD PDF covers alignment and what to expect from scans.
Export a change list as CSV and tick off every redline against it.
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How does Drawing Revision Delta help?
Drawing Revision Delta is a Windows app that compares two revisions of a drawing set on your PC. You pick a folder or files for the earlier revision and one for the later revision. PDFs, scanned TIFFs and other images are accepted, and multi-page files are split into sheets.
- Sheet matching by sheet number. Sheets are paired across the two sets by the sheet number in the title block. Where a sheet has no text layer, as with scans and many CAD plots, the app reads the title block with the text recognition built into Windows. You can correct any pair by hand.
- Alignment. Each pair is aligned for shift, rotation and scale, then corrected locally for the slight stretch different plotters and scanners introduce.
- The Pairs table shows how much of each sheet changed and sorts the most changed sheets first. New and missing sheets are listed.
- Views. Step through changes in Overlay (red only in the earlier revision, blue only in the later), Blink or Side by side, with revision clouds around each change. Where both PDFs have text, changed words are listed in plain terms, such as 2x6 to 2x8.
- Title block mask. Ignores date and revision-letter edits so they do not flood the list.
For the review record, it exports the later sheets with a revision cloud around every change as one PDF, with the clouds as PDF markups rather than drawn into the sheets; a PDF change report with a SHA-256 hash of every input file; a sheet summary and change list as CSV; and PNG snapshots. Files stay on your PC.
The CSV is the checklist for step 3 and step 4 above, and the PNG snapshots are what you send back with each gap. Note that the app finds differences between drawings; it does not read your redlines, so the matching of redlines to changes remains your review.
For the terms on the sheets themselves, see revision clouds and delta tags explained and what a conformed set is.
Frequently asked questions
Who prepares the record drawings?
It depends on the contract. Under UFGS 01 78 00 the contractor maintains the as-builts and, where specified, prepares the record drawings. Check your contract’s closeout section.
Should record drawings show revision clouds?
Practice varies by contract. The UFGS text for record drawings produced from a record model says not to include annotations indicating revisions. Follow your owner’s requirements; the clouded PDF from a comparison is a review tool, not the deliverable.
What if sheet numbers changed between the sets?
Correct the pair by hand in the Pairs table, so the right sheets are compared.
Does it need Windows 11?
Yes. The Store listing requires Windows 11.
Try Drawing Revision Delta
Drawing Revision Delta is a one-time purchase with a free trial in the Microsoft Store; the listing shows the current price and system requirements. Try it on one discipline of your record set before the full closeout review. More detail is on the Drawing Revision Delta product page.
Find the redlines that never made it into the record set.
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Last updated 23 October 2026. Published by Automata Labs, a software company in Canada.