ADU rules in Colchester

Section 2.09-B(1) allows one accessory dwelling unit accessory to a conforming residential use, and subsection (c) expressly contemplates the unit being 'located in the principal or an accessory structure', so a detached backyard cottage or above-garage unit qualifies. ADUs are not listed in Table A-1 at all: they are an accessory use reviewed through a zoning permit rather than a principal use that a district could exclude. A detached unit still has to meet the general accessory-structure rules in 2.09-A, notably a 10-foot separation from every property line and from the principal building, and the accessory-building floor-area caps in 2.09-A(4). Section 2.06-E specifically lets the Administrative Officer approve extra height for an accessory structure that includes an ADU, up to 20 feet or the height of the primary structure, whichever is less. Converting an existing detached outbuilding is protected by state law: 24 V.S.A. 4412(1)(E) requires that the criteria for converting a detached nonresidential building to habitable space for an ADU be no more restrictive than those for a single-family dwelling without one.

The same sentence in 2.09-B(1)(c) that permits a detached unit permits one inside the principal dwelling, so internal conversions, basement units, and additions are all on the same footing. Article 12 defines an accessory dwelling unit simply as 'a subordinate residential unit authorized by Title 24 VSA Section 4412(1)(E)' that 'does not consume allowable density on a parcel', which means adding one does not have to satisfy the district's density or minimum-lot-size math. Where the ADU is in a structure physically attached to the principal building, 2.09-A(1) subjects that structure to the dimensional requirements for principal buildings rather than the looser accessory-structure standards. Vermont law backs this up and got broader in 2026: as amended by Act 179, Sec. 9 (effective July 1, 2026), 24 V.S.A. 4412(1)(E) forbids any bylaw from excluding, as a permitted use, one ADU within or appurtenant to a single-family dwelling, with the former 'on an owner-occupied lot' qualifier now deleted.

Section 2.09-B(1)(e) sets the cap as the greater of the two figures, so a small house does not shrink the allowance below 900 square feet and a large house can support a bigger unit. Supplement 49, effective May 5, 2026, added the arithmetic: only contiguous habitable space of the principal dwelling counts toward the 30 percent base, and decks, porches, patios, pools, crawlspaces, and garages are excluded, while any structure, attached or detached, principally used by the ADU counts toward the ADU's own square footage. Bedrooms are capped separately: 2.09-B(1)(d) allows the unit no more bedrooms than the principal structure has. A detached unit is squeezed further by 2.09-A(4), which caps all accessory buildings together at 75 percent of the principal structure's ground floor with no single building over 50 percent, and by the 20-foot accessory-structure height ceiling.

Colchester's bylaw still demands it, but state law no longer lets it. Section 2.09-B(1)(a) reads 'The owner shall occupy either the principal dwelling or the ADU', and that sentence survived untouched into Supplement 49 on May 5, 2026. Seven weeks later, 2026 Act 179 (S.328), Sec. 9 struck the words 'on an owner-occupied lot' out of 24 V.S.A. 4412(1)(E) effective July 1, 2026, so the statewide guarantee of one ADU as a permitted use no longer turns on who lives on the lot. The statute is self-executing: 4412 opens 'Notwithstanding any existing bylaw, the following land development provisions shall apply in every municipality', and its parity sentence independently forbids ADU-specific controls that a single-family dwelling without an ADU would never face. Colchester's own drafting points the same way, since 2.09-B(1) applies 24 V.S.A. 4412(1) 'as amended from time to time'. Until the town amends the text, expect a zoning administrator to ask for it anyway.

Section 2.09-B(1)(g) requires off-street parking 'to include two parking spaces for the principal dwelling unit and one space for the ADU', and Table 10-2 in 10.01-O independently lists Accessory Dwelling Unit at '1 space per dwelling', so the ADU itself adds a single space. The combined three-space expectation is where Colchester runs ahead of state law: 24 V.S.A. 4414(4) provides that in any district served by municipal sewer and water infrastructure that allows residential uses, 'a municipality shall not require more than one parking space per dwelling unit'. The ADU's own one space sits exactly at that ceiling, so the ADU requirement is safe; the two-space requirement for the principal dwelling is the part that exceeds the cap in sewer-and-water-served districts.

An ADU needs only a zoning permit from the Administrative Officer, with no hearing. Section 2.09-B(1) introduces its seven criteria as the standards that 'shall be used when reviewing an application for a zoning permit', and 11.03-A requires a zoning permit 'issued by the Administrative Officer' for this kind of development. No discretionary board gets involved: 8.03-B(1) specifically excludes 'Single-unit dwelling on a single lot, its accessory structures, and related features' from site plan review, and because ADUs appear nowhere in Table A-1 there is no district in which they are flagged as a conditional use. The FY2027 fee schedule treats it as routine counter work, listing 'Accessory Dwelling Unit (ADU) $217'. The one timing wrinkle is that under 11.03-A(4) the permit is not effective until the 15-day appeal window closes.

Nothing in the Development Regulations limits renting an ADU on a long-term lease, and the Town's own homeowner guide names rental income as a reason to build one. Colchester has no short-term-rental ordinance and no rental registry: the Code of Ordinances runs Chapter 1 through Chapter 18 with no rental or lodging chapter, and the Development Regulations define no short-term rental use (the LS4 district purpose statement in 3.07-A merely acknowledges that lakeshore properties are used for 'short-term and long-term rentals'). The bylaw's owner-occupancy condition in 2.09-B(1)(a) used to mean both units could not be leased out at once, but 2026 Act 179 struck the owner-occupied-lot hook from 24 V.S.A. 4412(1)(E) effective July 1, 2026, so that constraint is preempted and a non-resident owner can in principle rent both. Vermont's statewide requirements still bite, including Division of Fire Safety short-term rental registration, the meals and rooms tax, and the Rental Housing Health Code. The regulations provide no mechanism to convey an ADU separately; it remains an accessory use on the same parcel and 'does not consume allowable density'.