West Virginia Code § 29-3-16a:
All new residential structures with fuel-burning heating or cooking sources, including existing buildings connected to newly built buildings containing fuel-burning appliances, must be equipped with at least one CO detector per building. CO detectors must be installed in apartment buildings, boarding houses, dormitories, long-term care facilities, adult or child care facilities, assisted living facilities, 1- and 2-family dwellings intended to be rented or leased, hotels, and motels in either (1) a common area where the general public has access; or (2) all rooms in which a person will be sleeping that are adjoining to and being directly below/above all areas or rooms that contain permanently installed fuel-burning appliances and equipment that emit CO. (Effective date: September 1, 2012)