What Is an Addendum in Construction?

A question from one bidder, if it reveals an ambiguity, should not be answered only to that bidder. The fair instrument is an addendum to the whole plan room. That is different from an RFI during construction, which is a contractor’s question after award. During bidding, the pre-bid question and the addendum are the pair.

Public procurement rules are strict about this. A change emailed to one general contractor and not to the others will not survive a bid protest. The addendum log, the issue date, and the acknowledgment line are the evidence that the playing field stayed level.

A change order modifies a signed contract and usually adjusts the contract sum or time. An addendum modifies documents that are not yet a contract. There is no contract sum to change, only a bid that has not been opened or has not been awarded. Teams that call a bid-period sketch a change order confuse the cost report later, because the "change" was actually base scope.

An architect’s supplemental instruction and a construction change directive are also post-award tools. The ASI is for a minor change with no effect on cost or time. The directive orders work when price is not yet agreed. Neither one is how you fix the bid set.

Number it, date it, and name the project. State the change in words and, when the drawings move, attach clouded sketches or full replacement sheets. Cite the spec section and the sheet. "Clarification: see attached" with no attached sheet is how bidders exclude the work.

Issue it early enough that bidders can reprice. An addendum the afternoon before bid day, changing structure or sitework, produces either a protest or a bid full of qualifications. Many public contracts set a cutoff, often several days before bids, after which only a postponement keeps the procurement clean.

After award, the conformed or issued-for-construction set should show the addenda on the sheets, not as a side stack. Revision clouds and a revision schedule let a detailer see that sheet A-401 changed in Addendum 2. Leaving the bid PDFs untouched and the addenda in a folder guarantees someone fabricates revision 0.

The specification sections need the same treatment. A drawing addendum that changes a roof without editing the spec section creates the first submittal argument of the job. Conforming means both volumes.