Conn. Gen. Stat. § 8-27: Building on unaccepted streets.

Any municipality having a planning commission may, by ordinance, prohibit or regulate the issuance of building permits for the erection of buildings or structures on lots abutting unaccepted highways or streets. No such ordinance shall prevent the issuance of a building permit for the construction of (1) farm or accessory buildings which are not in violation of any lawful zoning or building regulations of the municipality, or (2) any building or structure on a site plan approved on or after June 15, 2012, pursuant to subsection (g) of section 8-3 or in a subdivision approved on or after June 15, 2012, pursuant to section 8-25, provided the approval for such site plan or subdivision has not expired. Any building erected in violation of any such ordinance shall be deemed an unlawful structure, and the municipality through the appropriate officer may bring action to enjoin the erection of such structure or cause it to be vacated or removed. Any person, firm or corporation erecting a building or structure in violation of any such ordinance may be fined not more than two hundred dollars for each building or structure so erected in addition to the relief herein otherwise granted to the municipality.