Wisconsin Statutes Annotated §101.149:
New and existing multi-family dwellings including apartment buildings, rooming houses, hotels, children’s homes, community-based residential facilities, and dormitories (i.e., any public building used for lodging) must install CO alarms within 15 feet of sleeping areas in buildings that contain fuel-burning appliances and in any room in a basement with a fuel-burning appliance. (Effective date: April 7, 2008)