Every residential, nonresidential or mixed occupancy building and the land on which it is situated, used or intended to be used for dwelling, commercial business or industrial occupancy shall comply with the provisions of this chapter, whether or not such building shall have been constructed, altered or repaired before or after enactment of this chapter, and without regard to any permits or licenses which shall have been issued for the use or occupancy of the building or premises for the construction or repair of the building, or for installation or repair of equipment or facilities prior to the effective date of this chapter. This chapter establishes minimum standards for the initial and continued occupancy and use of all structures and does not replace or modify standards otherwise established for the construction, repair, alteration or use of the building. Where there is mixed occupancy, residential or nonresidential use therein shall be nevertheless regulated by and subject to the provisions of this chapter.