Iowa Code § 310.18: Partial payments during construction.

Partial payments may be made on work in progress, but such partial payment shall not be deemed final acceptance of the work nor a waiver of any defect in the work. The board of supervisors, the county engineer, or the department may approve partial and final claims. Approval may be evidenced by the signature of the county engineer or chairperson of the board or department, or a majority of the members of the board or department, on the individual claims or on the abstract of a number of claims with the individual claims attached to the abstract.