Idaho Administrative Code IDAPA 07.03.01(2012 IRC Adoption)::
Detached one- and two-family homes and townhomes (dwellings) of not more than three stories within which fuel-fired appliances are installed or which have an attached garage must install CO alarms in the general vicinity of each sleeping area. (Effective date: January 1, 2011)

Note: Although the Idaho Division of Building Safety has adopted the 2009 International Residential Code (IRC) requirements, each city or county is individually responsible for adopting and enforcing the building codes.

Rules Governing Standards for Child Care Licensing (pg 43):
Foster homes shall at least one CO detecting device that is approved by a nationally recognized testing laboratory.