ADU rules in South Burlington

Section 3.11(A) of the Land Development Regulations permits one accessory dwelling unit "within or appurtenant to a single-family dwelling on the same lot," and the detached form is contemplated throughout the section rather than merely tolerated. Subsection (A)(7) sets criteria for converting an existing detached nonresidential building into ADU habitable area, and (A)(8) lets an ADU sit wholly or partly inside the required setback wherever an accessory structure could be placed, provided its principal entry does not face a side or rear lot line. The Article 2 definition of "Building, principal" expressly carves out ADUs, so a detached backyard unit is not a second principal building and does not trigger the multiple-structure rules of Section 3.09. Detached units are not capped by the general accessory-structure standards in Section 3.10, which set placement and setback rules but no citywide floor-area or height limit.

The same sentence in Section 3.11(A) covers an ADU located "within" the single-family dwelling, so basement conversions, upper-floor units and additions qualify on identical terms with no separate standard or added review. Section 3.11(A)(4) reinforces the point: regulation of a single-family home with an ADU "shall not be more restrictive than the criteria used for a single-family dwelling without an accessory dwelling unit," which forecloses extra dimensional or procedural burdens on an internal conversion. Site plan review does not apply, since Section 14.03(B)(1) exempts a one-unit dwelling on a single lot and its accessory structures, and Section 14.03(B)(7) separately exempts renovations that are entirely internal to an existing building. Only a zoning permit from the Administrative Officer is needed.

Section 3.11(A)(2) caps the accessory unit at "thirty percent (30%) of the total habitable area of the single-family dwelling or 900 square feet, whichever is greater," which tracks the statewide ADU definition at 24 V.S.A. § 4303(38) exactly; Act 179 of 2026 did not amend § 4303, so that definition and its 900 sq ft floor are unchanged. There is no ADU-specific height limit in the base districts; district dimensional standards apply as they would to a single-family dwelling, and story heights are capped at 12 feet in the LSN and Queen City Park districts and 24 feet for a ground story elsewhere under Section 3.07(C). The practical binding constraint on a small lot is usually coverage rather than the 900 sq ft figure, because Section 3.11(A)(5) folds the ADU and its associated coverage into the lot's building and lot coverage computation. Two special contexts add form limits: in a Traditional Neighborhood Development PUD the ADU takes the Article 11C "Carriage House" building type at 1 to 1.5 stories, and the City Center Form Based Code T3 and T3+ zones have their own, more generous Carriage House building type.

Not lawfully since July 1, 2026, although the city's unamended text still says otherwise and you should expect to meet it at the counter. Section 3.11(A)(1) makes "The lot is owner-occupied" a standing condition of the permitted use, copied from 24 V.S.A. § 4412(1)(E) as that statute read through mid-2026, when it obliged municipalities to allow one ADU only "within or appurtenant to a single-family dwelling on an owner-occupied lot." Vermont Act 179 of 2026 (S.328), Sec. 9, struck the phrase "on an owner-occupied lot" effective July 1, 2026. Two independent hooks in the amended statute now void the local condition: § 4412(1)(E) is drafted as a prohibition on bylaws, not as a floor grant, so once the qualifier is gone "no bylaw shall have the effect of excluding as a permitted use" an ADU appurtenant to any single-family dwelling; and the surviving parity sentence separately forbids subjecting a single-family dwelling with an ADU to review or other controls not imposed on one without, which an owner-occupancy condition plainly is. Section 4412 is headed "REQUIRED PROVISIONS AND PROHIBITED EFFECTS" and binds "[n]otwithstanding any existing bylaw," so it operates without waiting for the city to amend Section 3.11, which it had not done as of August 4, 2026. No enforcement of the condition since July 1, 2026 has been identified either way. Owner occupancy does still matter for short-term rental use, which is governed by a separate and unpreempted ordinance: Code of Ordinances § 23-3(c)(1)c.1 requires a primary residence affidavit plus a driver's license, motor vehicle registration, homestead declaration or equivalent proof of residency at the dwelling the ADU is accessory to.

South Burlington has abolished residential parking minimums except for multi-family buildings. Section 13.02(B)(1) provides that "Except as specifically provided in Table 13-1, there shall be no minimum number of parking spaces," and Table 13-1 lists only two rows, both multi-family: 0.75 spaces per studio or one-bedroom unit and 1.0 space per unit with two or more bedrooms. Single-family dwellings and their ADUs appear nowhere in the table, so no off-street space is required for an ADU anywhere in the city. That is more permissive than the statewide ceiling in 24 V.S.A. § 4414(4), which merely bars a municipality from requiring more than one space per dwelling unit in districts served by municipal sewer and water; Act 179 of 2026 did not amend § 4414, so that ceiling is unchanged. The pending LDR-26 amendment package leaves Section 13.02(B)(1) and Table 13-1 unchanged.

Section 3.11 is headed "Accessory Dwelling Units" with subsection A titled "Permitted Use," and the only process it imposes is subsection (A)(6): "A zoning permit shall be required for the establishment of an accessory dwelling unit." Zoning permits are issued administratively by the Administrative Officer under Section 17.02(A), with no Development Review Board hearing, conditional use approval or warned public notice. Site plan review is expressly excluded for a one-unit dwelling on a single lot and its accessory structures under Section 14.03(B)(1). The Appendix C Table of Uses does not assign ADUs a per-district P or C letter at all; the "Accessory residential units" row simply reads "See ADU Regulations," pointing back to Section 3.11, so the right does not vary by district. Applications are filed through the city's online Permitting & Registration Portal.

The Land Development Regulations place no limit on who may occupy an ADU, and because the Section 3.11(A)(1) owner-occupancy condition runs to the lot, the owner can live in one unit and rent the other. Renting triggers Chapter 23 of the Code of Ordinances, the Residential Rental Registry adopted February 20, 2024 and effective April 1, 2024: every rental unit, long-term or short-term, must be registered with the city by April 1 each year, pay the fee, and permit on-site inspection under § 23-3(a). Short-term rentals (fewer than 30 consecutive days per guest and more than 14 days a year) are restricted by § 23-5(c) to units that are owner-occupied, tenant-occupied with the owner's permission, or an accessory dwelling unit, so an ADU is squarely eligible where an ordinary non-owner-occupied house is not. Short-term registration additionally requires a primary residence affidavit, at least $1,000,000 in liability coverage, and proof of a Vermont rooms and meals tax account (§ 23-3(c)); guest occupancy is capped at two per bedroom plus two, and civil penalties reach $800 per day (§§ 23-5(a), 23-8). Act 179 of 2026 does not disturb any of this: Chapter 23 is a civil police-power ordinance adopted under 24 V.S.A. § 2291 rather than a zoning bylaw, and § 4412(1)(F)(ii) expressly preserves "a bylaw that regulates short-term rental units distinctly from residential rental units," so the short-term primary-residence test survives the removal of owner occupancy from the zoning floor.