A late addendum is where good bids quietly break: the estimate was checked, then the documents changed. Work this list every time an addendum drops — especially inside the last 48 hours. Free, no sign-up.
Read the addendum narrative AND every reissued sheet — the narrative rarely lists everything that changed on the drawings.
Build a one-line delta list as you read: sheet, what changed, estimate line affected. If a change has no estimate line, that's the finding.
Check which earlier addenda this one modifies or supersedes — addendum 3 quietly editing addendum 1 is a classic miss.
Confirm the bid date and time. Addenda move deadlines more often than estimators re-check them.
2 · The big-money reissues
Fixture schedule reissued? Re-count types that changed, confirm your lighting quote is against the NEW schedule revision, and get that in writing from the vendor.
One-line or riser reissued? Re-check gear ratings, breaker counts, feeder sizes and lengths against your gear quote and feeder takeoff.
Panel schedules reissued? Circuit counts move device and wire quantities — spot-check the panels with the most changes.
Specs reissued? Diff the Division 26/27/28 sections: basis-of-design swaps, added testing or commissioning, new submittals, warranty changes.
Site/civil sheets reissued? Re-check site lighting, pole bases, duct banks, and trenching ownership — scope boundaries move on addenda too.
3 · Quotes that just went stale
Every vendor/sub quote dated BEFORE the addendum: does it still match the documents? Their quote says 'per plans and specs' — which revision?
Lighting, gear, and fire alarm quotes are the usual casualties — confirm each against the addendum delta list, by email, before bid close.
A supplier who hasn't seen the addendum is pricing a different job. Forward it and ask for written confirmation or a revised number.
4 · The bid form, last
Acknowledge every addendum by number on the bid form — an unacknowledged addendum can make the bid non-responsive.
Re-read alternates and unit prices: addenda add, delete, and redefine them late. Price what the CURRENT bid form asks for.
If the addendum changed allowances or cash allowances, carry the new figure exactly as written.
Final pass: your qualifications letter — anything the addendum made ambiguous gets carried, RFI'd, or qualified in writing.
Addenda are exactly what re-reviews are for.
Upload the addendum and Bidprobe re-reviews the whole package against it — what changed, what it touches in your estimate, and the RFIs still worth sending. Re-reviews are included on every plan, and your first review is free. See a complete sample report.