In interpreting and applying the provisions of this chapter, they shall be held to the minimum requirements adopted for the promotion of the public health, safety, comfort, convenience, prosperity and general welfare. Unless specifically provided for, it is not intended by this chapter to repeal, abrogate, annul or in any way to impair or interfere with the existing and unrepealed provision of law or ordinance or any rules, regulations or permits previously adopted or issued pursuant to law relating to the use of building or land, provided, however, that where this chapter imposes a greater restriction upon the use of buildings or structures or land or upon the height, area or size of buildings or requires larger yards, courts or other open spaces than are imposed or required by such existing provisions of law or ordinance or by such rules, regulations or permits, the provisions of this chapter shall control.