Whenever the department has reasonable cause to believe that there exists in any building or premises any condition nonconforming with this title, the department may enter such building or premises. If the building or premises is occupied, the department shall first present proper credentials and demand entry; and if the building or premises is unoccupied, the department shall first make reasonable effort to locate the owner or other persons having charge or control of the building or premises and request entry. If such entry is refused the department shall have recourse to secure entry.