Iowa Code § 573.27
Notwithstanding anything in this Code to the contrary, when at least ninety-five percent of any contract for the construction of public improvements has been completed to the satisfaction of the public contracting authority and owing to conditions beyond the control of the construction contractor the remaining work on the contract cannot proceed for a period of more than sixty days, such public contracting authority may make full payment for the completed work and enter into a supplemental contract with the construction contractor involved on the same terms and conditions so far as applicable thereto for the construction of the work remaining to be done, provided however, that the contractor's surety consents thereto and agrees that the bond shall remain in full force and effect.
Iowa Code § 573.27