In this chapter, the work specified in a contract is taken to be completed when, with any variations, omissions or deductions authorised or agreed, it has been performed in accordance with the contract, whether or not the contractor—
(a) is later employed to do additional work that is connected or related to the work but is not specified in the contract; or
(b) is liable to rectify defects in the work discovered after the performance of the work and during a defects liability period for the contract.