Wis. Stat. § 101.645: Smoke detectors.

(1) Definition. The definition of “smoke detector” under s. 101.145 (1) (c) also applies to this section.

(2) Approval and installation. A smoke detector required under this section shall be approved and installed as required under s. 101.145 (2) and (3) (a).

(3) Requirement. The owner of a dwelling shall install a functional smoke detector in the basement of the dwelling and on each floor level except the attic or storage area of each dwelling unit. The occupant of such a dwelling unit shall maintain any smoke detector in that unit, except that if any occupant who is not the owner, or any state, county, city, village or town officer, agent or employee charged under statute or municipal ordinance with powers or duties involving inspection of real or personal property, gives written notice to the owner that the smoke detector is not functional the owner shall provide, within 5 days after receipt of that notice, any maintenance necessary to make that smoke detector functional.

(4) Inspection. Except as provided under s. 101.64 (2m), the department or a municipal authority may inspect a new dwelling, may inspect the common areas of a dwelling, and, at the request of the owner or renter, may inspect the interior of a dwelling unit in a dwelling to ensure compliance with this section.