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, morals, comfort, prosperity and general welfare. It is not intended by this chapter to repeal, abrogate, annul or in any way impair or interfere with any existing provisions of law or ordinance or with any rules, regulations or permits previously adopted or issued or which shall be adopted or issued pursuant to law relating to the uses of building or land, or with any private restrictions placed upon a property by covenant or deed; provided that where this chapter requires a greater width of size, or yards, courts or other open spaces, or requires a greater percentage of lot to be left unoccupied, or imposes restrictions more extensive than are required by any other statute or local ordinance or regulation, the provisions of the regulations in this chapter shall govern.