No lot shall contain any building used in whole or in part for residential, commercial, or industrial purposes unless such lot abuts at least one established public or private street. The minimum street frontage for each such lot shall be the minimum lot width as required based on the zoning of the property unless the lot is an approved flag lot. Flag lots, when permitted, shall have at least forty (40) feet of frontage on at least one street, and must be approved either by the Zoning Administrator via a Plat of Survey or by the Board via a Plat of Subdivision. For lots established after the effective date of this Ordinance, access easements shall not be considered acceptable frontage for building purposes. For agricultural purposes only, access may be provided via a private easement at least twenty (20) feet wide to a public or private street. Private streets shall be established only via a Plat of Subdivision and shall meet the subdivision regulations in accordance with Chapter 56.