Whenever necessary any member of the Enforcement Agency or its authorized agent may, upon proper authorization, enter such buildings at all reasonable times to inspect same or perform any duties required under this article; provided that if such building is occupied, he shall first present proper credentials and request entry, and if such building is unoccupied, he shall first make a reasonable effort to locate the owner or other persons having charge or control of the building and request entry. If any request for entry is refused, then any member of the Enforcement Agency or its agents shall have recourse to every remedy provided by law to secure entry.