AEC definitions
A bid alternate is a separately priced piece of scope on the bid form. An add alternate states the cost to add work. A deduct alternate states the credit to remove work. The owner decides which alternates to accept, in the order the instructions require, without asking bidders to reprice the base.
Definition
Alternates exist so an owner can match a bid to a budget after opening, inside rules set before the bids. The base bid must stand alone. An alternate that the building cannot function without is not an alternate. It is missing base scope. Each alternate needs drawings and specifications, not a one-line description. After award, accepted alternates are in the contract. Rejected ones are not, unless a later change order adds them at a new price.
In depth
If the base bid omits the roof, an 'alternate' for the roof is the project. Alternates are for genuine options: a better facade, an extra classroom, a deduct to leave a floor as shell.
Bidders price the base as if no alternate will be taken, then price each alternate as a difference. Instructions should say whether alternates include their own general conditions.
Public bids often require the owner to accept alternates in the published order, so the low bidder cannot be rearranged after opening. Read the statute and the instructions. Private owners may reserve more freedom, if they said so.
Taking alternates out of order, or inventing a new combination, can change who is low. That is a protest.
A note that says 'alternate 2: upgrade stone' without a basis and an extent will produce three different prices. Show the area, name the base product, and name the alternate product.
Deduct alternates must say what remains. Deducting a finish without saying the substrate gets patched is how a credit comes back smaller than the owner expected.
The contract should list the base and each accepted alternate with its amount. A notice of award that is silent, while everyone 'knows' alternate 1 was taken, is a poor record.
Rejected alternates are not a menu for later at the bid price, unless the instructions promised a hold period. After that, the work is a change.
A bidder who puts base scope into an alternate looks cheaper on the base and expensive on the alternate. Leveling has to test that the bases match.
Subcontractor alternates have to roll into the prime alternate. A GC who carries a trade alternate in the base has not bid the form.
Examples
Alternate 1 adds a green roof for a stated price. The owner accepts it because the base plus alternate 1 fits the budget. The agreement lists both.
A deduct alternate removes casework from two rooms and states that walls are painted in its place. The credit matches that description.
The instructions say alternates are accepted in order. The owner takes alternate 1 and not alternate 2. They do not take alternate 2 alone.
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