A conformed set is the bid drawings and specifications reissued after award with every addendum item and accepted alternate written into the sheets, so the contractor builds from one clean set instead of a bid set plus a stack of addenda. To check one, compare the bid set with the conformed set sheet by sheet and make sure every change you find traces to an addendum item or an accepted alternate, and that every addendum item shows up as a change. Drawing Revision Delta, a Windows app from Automata Labs, does the sheet-by-sheet part: it pairs the two sets by sheet number, ranks the sheets that changed, clouds every change and lists edited notes and dimensions in words.
This matters because a conformed set is a convenience, not the contract. If the architect missed an addendum item while conforming, or slipped in a change that was never issued, the field is building from a set that does not match what was bid.
Compare the bid set with the conformed set and see every changed sheet, ranked.
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What does “conformed set” mean, exactly?
Definitions vary by owner and contract form, so read your own general conditions. A clear public example is the Ohio Facilities Construction Commission’s contracting definitions for general contracting projects, which define Conformed Documents as “Contract Documents with all Addenda items and accepted Alternates incorporated by the A/E, published, and issued to a successful Bidder for its use during performance of the Contract.” The same definition adds that the Conformed Documents “are furnished solely for the Contractor’s convenience. In the event of any conflict between the Contract Documents modified by Addenda and the Conformed Documents, the Contract Documents take precedence.” (OFCC General Contracting documents, Document 00 71 00)
That last sentence is the reason to check. Under that kind of clause, the bid set plus the addenda is what governs. The conformed set is supposed to be the same thing in one place.
How is a conformed set different from bid, construction and record sets?
| Set | When it is issued | What it contains |
|---|---|---|
| Bid set | For bidding | The design as bid, before addenda |
| Addenda | During bidding | Changes and clarifications issued before bids close, often with reissued sheets |
| Conformed set | After award | The bid set with addenda and accepted alternates incorporated |
| Construction changes | During construction | Bulletins, ASIs, change orders; each changes the set again |
| Record drawings | At closeout | Under the OFCC definition, drawings revised by the A/E to show changes made during construction, conformed to represent the work as executed |
Terminology differs between firms; some call the conformed set the issued-for-construction set, and some issue both. The check below works for any pair: an earlier set and a later set that is supposed to differ only by known, listed changes.
Why can a conformed set disagree with the addenda?
Conforming is a manual drafting task done under schedule pressure, after bidding, often by someone who did not write the addenda. Common slips:
- An addendum item that never made it in. A note change in Addendum 2 is on the reissued addendum sheet but not on the conformed sheet.
- The wrong version of a reissued sheet. A sheet reissued in Addendum 1 and again in Addendum 3 gets conformed from the Addendum 1 version.
- Alternates handled the wrong way. An alternate that was not accepted is shown as if it were, or an accepted one is left out.
- Unlisted changes. Design development that continued after bidding appears in the conformed set without an addendum or a change order behind it.
- Sheets added or dropped. A sheet issued by addendum is missing from the conformed index, or a deleted sheet is still there.
Each one is a cost or schedule question that is far cheaper to raise before work starts than after.
How do you check a conformed set against the addenda, step by step?
- Collect the documents. The bid set, every addendum with its reissued sheets and its written list of changes, the list of accepted alternates from the contract, and the conformed set.
- Build an expected-changes list. From each addendum, list the sheet and the change. Add the accepted alternates. This is your checklist.
- Compare the bid set with the conformed set, every sheet. Find every difference, not just the ones you expect.
- Match each difference to the list. A difference with an addendum item or accepted alternate behind it is expected. A difference with nothing behind it is a question for the architect.
- Check the list against the differences. An addendum item with no matching difference on the conformed sheet means it was missed.
- Check the sheet index. Sheets new in the conformed set should come from an addendum; sheets missing should have been deleted by one.
- Write it up. Send a short log of unmatched changes and missing items to the architect, and keep it with the contract documents.
Steps 3 and 6 are the slow part when done by flipping between two PDFs, and they are where a comparison tool pays for itself. Steps 2, 4 and 5 are judgement, and stay with you.
How does Drawing Revision Delta help?
Drawing Revision Delta compares two revisions of a drawing set on your PC.
| Step | What Drawing Revision Delta does |
|---|---|
| Load the sets | Pick a folder or files for the earlier set (the bid set) and the later set (the conformed set). One combined PDF, a file per sheet, or scanned TIFF, PNG, JPEG and BMP all work; multi-page files are split into sheets |
| Pair sheets | Matches sheets by the sheet number in the title block, from the PDF text or with Windows text recognition when there is no text layer. Any pair can be corrected by hand |
| Align and compare | Aligns each pair for shift, rotation and scale, corrects locally for plotter and scanner stretch, and compares at the resolution and sensitivity you choose |
| Rank | The Pairs table shows how much each sheet changed and sorts the most changed first; sheets new in the later set or missing from it are listed |
| Review | Overlay (red only in the earlier set, blue only in the later), Blink or Side by side, with revision clouds around each change |
| Read text edits | Where both PDFs have text, changed words are listed in plain terms, for example 2x6 to 2x8 |
| Ignore noise | A mask over the title block ignores date and revision-letter edits |
| Export | The later set’s sheets with a revision cloud markup around every change, a PDF change report with the changed-sheet list and a SHA-256 hash of every input file, CSV files of sheets and changes, and PNG snapshots |
The changes CSV is the useful one for this job. Open it in Excel next to your expected-changes list and mark each row with the addendum item it belongs to. Whatever is left unmarked on either side is your question list.
Export every change as a CSV and match it to the addenda in Excel.
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A second pass: conformed set against the last addendum sheets
When a sheet was reissued in an addendum, run a second comparison between the latest addendum version of that sheet and the conformed sheet. They should match, apart from the title block. Mask the title block so the revision letter and date do not count, and any remaining difference is either a later change or a conforming error. This pass catches the wrong-version problem directly.
Our addendum drawing review checklist covers reviewing each addendum as it arrives during bidding, and the addendum comparison page shows the comparison itself. For the symbols you will see on the sheets, see revision clouds and delta tags explained.
What a comparison cannot tell you
- Whether a change was authorised. The tool finds differences; the addenda and contract say which ones are allowed.
- Changes in the specifications. Drawing Revision Delta compares drawing sheets. Project manual sections need their own review.
- Anything finer than the comparison resolution. Comparison runs at the resolution and sensitivity you choose; very small marks on a noisy scan may need a closer look at a higher setting.
- Legal effect. Which document governs depends on your contract. The OFCC wording above is one example, not a rule for every project.
Frequently asked questions
Is a conformed set the same as an issued-for-construction set?
Often, but not always. Some firms use the terms interchangeably; others issue a conformed set and later an issued-for-construction set with further changes. Check what your contract and the architect’s transmittal call it.
Who prepares the conformed set?
Usually the architect or engineer of record, after award. Under the OFCC documents quoted above, the A/E incorporates all addenda and accepted alternates and provides the conformed documents to the contractor.
What happens if the conformed set and the addenda disagree?
It depends on the contract. Under the OFCC definition, the contract documents as modified by addenda take precedence over the conformed documents. Raise any disagreement in writing with the architect.
Can I compare a scanned bid set with a CAD-plotted conformed set?
Yes. Drawing Revision Delta reads title blocks with Windows text recognition when a sheet has no text layer and corrects for scanner stretch. Our guide to comparing scanned drawings with CAD PDFs covers what to expect.
Are my drawings uploaded?
No. Drawing Revision Delta runs on your PC, reads only the files you pick, and has no account, sign-in or telemetry.
Try Drawing Revision Delta
Drawing Revision Delta is a one-time purchase in the Microsoft Store with a 15-day free trial. It runs on Windows 11, x64 and Arm64. Load your last bid set and its conformed set during the trial and see how long the check takes. More detail is on the Drawing Revision Delta product page.
Check your next conformed set against the bid set during the 15-day free trial.
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Microsoft Excel and Windows are trademarks of the Microsoft group of companies. Drawing Revision Delta is not affiliated with the Ohio Facilities Construction Commission. This article is not legal advice.
Last updated 19 October 2026. Published by Automata Labs, a software company in Canada.