answer:Do you have an estimate or a contract? An estimate is not a promise, after all, but an educated guess. A contract, on the other hand, is more authoritative. If the contractor made you a solid offer of a shed for $2,000, then you should not have to pay for his mistake. Indeed, he’ll never learn his lesson if you do. And if you have a contract for a shed in exchange for $2,000, then there’s really no way for him to force you to pay more. Before you decide what to do, however, remember that there’s more to the situation than your legal obligations. Just because something is legal doesn’t mean it is right. What would be the consequences of making the guy take a loss on this job? What would be the consequences for you of paying more than $2,000. Perhaps you could assert your right to pay only $2,000 to remind him of the lesson here, but agree to pay $3,000 as a compromise. I’m not saying you should definitely do that. You’re the one in the best position to figure out what the personal and economic effects on you and the contractor would be. It isn’t fair for the contractor to take no loss on the project since it was his mistake, but that doesn’t mean you have to make him suffer.