Iowa Administrative Code 661-301.8(103A) (2009 IRC Adoption):
Detached one- and two-family dwellings and townhomes of not more than three stories within which fuel-fired appliances are installed or which have attached garages are required to install CO alarms. (Effective date: January 1, 2010)

IAC Rule 661.202.2:
Foster Care: Facilities in which foster care is provided to fewer than six children shall install a carbon monoxide detector on each floor of the residence.