ADU rules in Danbury

Danbury allows no detached accessory dwelling of any kind. Section 3.G.2 states flatly that 'No accessory building shall be used as a residence,' and Section 3.C.1 closes the use lists: 'All other uses not expressly allowed within a zoning district are prohibited.' In the four single-family districts (RA-8, RA-20, RA-40 and RA-80) Section 4.A.2 lists only six permitted uses, of which the sole residential one is a one family dwelling, and Section 4.A.4.e adds that 'Only one principal dwelling per lot shall be permitted, except as part of a cluster development.' Accessory apartments were a special exception use in Danbury until 2015, when the Zoning Commission deleted the use; the city then opted out of the state accessory-apartment mandate in 2022 (Section 3.C.7), so no statewide floor applies.

An attached, basement or interior second unit is equally unavailable on a single-family lot. Section 2.B defines 'Dwelling, one family' as 'A detached building with one dwelling unit,' and a 'Dwelling unit' as living quarters with 'provisions for living, dining, kitchen and bathroom facilities for the exclusive use of the occupants,' so finishing a wing or basement with its own kitchen creates a second dwelling unit and turns the house into a two family dwelling, a use the RA districts do not list. The practical line is the kitchen: an in-law suite, au pair room or bedroom wing without cooking facilities is not a dwelling unit and remains lawful. A genuine second unit is legal only where a two family dwelling is itself a permitted principal use, and there it is a co-equal two-unit building rather than an accessory apartment.

Because Danbury authorizes no accessory dwelling, it states no floor area, footprint or height standard for one. The nearest numbers govern ordinary detached accessory buildings, which may not be residences: Section 3.G.3 caps them at fifteen (15) feet in height and requires that, combined with other accessory buildings on the lot, their total ground floor area not exceed fifty percent (50%) of the total ground floor area of all principal buildings. Section 4.A.3 gives detached accessory uses reduced yards (6-foot side and rear in RA-8 and RA-20; 15-foot side and 20-foot rear in RA-40; 30 feet in RA-80). Had Danbury not opted out, CGS 8-2o(a)(3) would have forced a size allowance of at least the lesser of 30 percent of the principal dwelling's net floor area or 1,000 square feet.

Danbury states no owner-occupancy rule for accessory apartments because it creates no accessory apartment use to regulate; the regulations are silent rather than permissive, which is why this reads 'unknown' rather than 'no'. Owner occupancy does surface nearby: Section 2.B defines both a 'Boarding house' and a 'Rooming house' as a building 'that is the primary residence of the owner,' and Section 4.B.5.b permits rooming and boarding houses in the RMF-4 zone only. Note that CGS 8-2o never barred municipal owner-occupancy mandates; they are absent from the subsection (a)(6) prohibition list, so Danbury could have imposed one even had it complied instead of opting out. If the Zoning Commission reinstates accessory apartments, read this field fresh.

Section 8.C.4.f(1) requires '2 per dwelling unit plus 1 per 2 resident employees' for one, two and three family dwellings, and the table has no accessory-apartment row. Danbury's local Section 3.C.6, effective 1-28-2022, opted out of the old P.A. 21-29 parking caps (City Council 2-1-2022), but that opt-out is now history rather than live law: Nov. Sp. Sess. P.A. 25-1, S. 53 repealed CGS 8-2p effective 1-1-2026, and S. 18 rewrote CGS 8-2(d)(9) effective 7-1-2026 so that zoning may not 'require a minimum number of off-street motor vehicle parking spaces for any residential development except as provided in section 8-3n,' with the opt-out clause deleted. New CGS 8-3n (S. 19, effective 7-1-2026) now governs: an application for residential development may not be rejected solely for failing a parking requirement unless the commission finds a specific adverse impact on public health and safety that conditions cannot mitigate, and minimums may be required only for developments of more than sixteen dwelling units, or inside up to two locally adopted conservation and traffic mitigation districts. The CGS 8-2o(a)(6)(C) bar on requiring more than one parking space for an accessory apartment is separately inoperative here because of the accessory-apartment opt-out.

There is no ADU permit pathway of any kind, so no review type can be recorded. Zoning permits under Section 10.B.1 are ministerial, issued by the Zoning Enforcement Officer, but only 'upon a finding by the Zoning Enforcement Officer that the proposed activity is in compliance with the Zoning Regulations,' which an accessory apartment never is. The variance route is closed by name rather than merely difficult: Section 11.B.2.a provides that 'No use variance shall be granted by the Zoning Board of Appeals for any parcel located within a RA-8, RA-20, RA-40, or RA-80 zone,' and Section 11.B.2.d adds that the Board 'shall not grant a variance to allow a use not permitted presently under any zone in these Regulations.' The only realistic routes are a Zoning Commission text amendment or a map change to a district where two family dwellings are permitted.

Units created before the 2015 repeal survive only as nonconforming uses: Section 9.A allows any use 'lawfully existing or in use at the time of the adoption of these Regulations, or any amendment which renders the use or building nonconforming' to continue, but Section 9.C.2.a provides that 'No nonconforming use shall be extended or expanded,' and Section 9.C ends the protection on abandonment. The Code of Ordinances has no short-term-rental licensing chapter: chapter 26 covers only closing-out sales and entertainment licenses, and chapter 20 (Housing) holds a Fair Rent Commission under CGS 7-148b (art. III, §§ 20-53 et seq.) and a Maintenance and Occupancy Code (art. IV), with no rental registration for one and two family homes. CGS 8-2o(a)(7)(B) expressly preserves a municipality's power to prohibit or limit accessory apartments as short-term rentals, which is moot in an opt-out town with no such units.