Shall not be enlarged, altered, extended, reconstructed or restored, except as provided below, or placed on a different portion of the lot or parcel of land occupied by such use on the effective date of this chapter, nor shall any external evidence of such use be substantially increased by any means whatsoever. Notwithstanding the foregoing, an owner of real property located in a HM, CM, or C District and which is being lawfully used as a "one-family dwelling" pursuant to legal non-conforming use shall be permitted to improve said property with a private garage or carport as a permitted accessory use, provided that the area and bulk requirements applicable to RA Districts are met and subject to compliance with all applicable requirements of the Town Code.