I have yet to find references requiring CO alarms, I am sure I am just looking in the wrong locations (we do have one jurisdiction in Utah that has a law requiring them in all residences).
The requirement in Utah comes from a statewide amendment to the building code that applies in all jurisdictions in Utah. The Utah amendments to the codes can be found in
this document . An amendment to IBC (2006) Section 907.2.10 can be found in Section R156-56-704(24) of that document, and an amendment to IRC Section R313.1 can be found in Section R156-56-711(16) of the document. These amendments require CO detectors in all Utah jurisdictions.
