In their interpretation and application, the provisions of this chapter shall be held to be the minimum requirements adopted for the promotion of the public health, safety, comfort, convenience and general welfare. It is not intended by this chapter, except as provided in § 335-26, to repeal, abrogate, annul or in any way to impair or interfere with any existing law or ordinance or any rules or regulations relating to the use of buildings or premises; provided, however, that where this chapter imposes a greater restriction upon the use of buildings or premises or upon heights of buildings, or requires larger yards, courts or other open spaces, than are imposed or required by such existing provision of law or ordinance or by such rules or regulations or permits, the provisions of this chapter shall govern.