The homestead may be sold to satisfy debts of each of the following classes:
1. Those contracted prior to its acquisition, but then only to satisfy a deficiency remaining after exhausting the other property of the debtor, liable to execution.
2. Those created by written contract by persons having the power to convey, expressly stipulating that it shall be liable, but then only for a deficiency remaining after exhausting all other property pledged by the same contract for the payment of the debt.
3. a. Those secured by a mechanic’s lien under chapter 572, including reasonable attorney fees as provided under section 572.32, subsection 1.
b. Those incurred for work done or material furnished, including principal and interest on any note securing the purchase of such material, exclusively for the improvement of the homestead.
4. If there is no survivor or issue, for the payment of any debts to which it might at that time be subjected if it had never been held as a homestead.
Homestead acquired with pension funds, §627.9
Liability for assistance furnished poor person, §252.14