Maryland Code Annotated §12-1101 to 1106:
New construction of residential dwellings (single- and multi-family) and non-residential dwellings (hotels, motels, dormitories) must be equipped with CO detectors in accordance with NFPA 720. (Effective date: January 1, 2008)

2015 IRC and IBC Adoption:
New one- and two-family dwellings and townhomes of not more than three stories must be equipped with CO alarms or detectors outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units within which fuel-burning appliances are installed and in dwelling units that have attached garages. Group R occupancies (e.g., hotels, motels, dormitories, and dwelling units within apartment buildings) are required to install CO alarm or detectors. (Effective with adoption of 2012 IRC and IBC in January 2013)