Change Order
A formal, written change to the original contract, adjusting the scope of work, the price, the schedule, or all three, that both the owner and contractor agree to.
Why it matters
Nothing changes on a project's price or timeline without one. A change order is what protects a contractor from doing extra work for free, and protects an owner from paying for something they didn't actually approve.
On a real project
An owner decides mid-project they want upgraded countertops instead of the ones in the original plans. The contractor prices the difference, and both sides sign a change order before the new countertops get ordered.
Who this matters most to
A Project Manager lives inside this process day to day: chasing signatures, pricing changes, and keeping the schedule honest is one of the most constant parts of the job. A Superintendent cares just as much from the field side, since they're often the one deciding whether work can actually start before the paperwork has caught up.
Where this goes wrong
A subcontractor gets a verbal "yes, go ahead" on a $12,000 scope change and starts work immediately. Three weeks later the owner disputes the number, insisting they remember a lower figure, and nobody can find anything in writing to settle it. The subcontractor either eats the difference or spends weeks fighting for money that a signature up front would have secured in thirty seconds.