No zoning permit shall be required for the continuation of previously approved or permitted uses and structures, uses and structures that are not subject to any building or zoning regulations, or other uses or buildings already subject to administrative use permits, temporary use permits, conditional use permits, variances, or other discretionary approvals in the district in which they are located. [Ord. 14-12 § 1; Res. 14-36 § 503.05.]