158. Extras.

If a person without any order or request does more work than was originally stipulated for in the contract, and the hirer did not acquiesce in the change, although the extra work is essential to the proper performance of the contract, the hirer, in the absence of bad faith or concealment1, is not bound to pay more than the sum originally agreed upon by him2. So if a person, employed to do specified work on a chattel for an agreed sum, instead of doing the specified work does different, even if better, work, he or she can recover from