ADU rules in Pittsfield

A detached backyard ADU is allowed by right. Section 9.101H, added 2-11-2025 by Ord. No. 1315 (nine days after the Massachusetts by-right ADU law took effect on February 2, 2025), provides that one ADU is permitted by right on any property containing a one- or two-family residential use, and the Section 2.2 glossary says an ADU 'can be attached or detached from the principal structure.' Ord. No. 1315 also rewrote the surrounding accessory-building limits so they do not bite: Section 9.101D exempts ADUs from the rear-yard placement rule, Section 9.101E exempts them from the 15-foot height cap, the 10-foot separation from the principal building and the 10 percent lot-coverage cap, and Section 9.101G lets a shipping container be used as an ADU if modified to appear residential in character. The one place detached ADUs are restricted is the Downtown Creative District, where the Section 4.324 use table (also amended by Ord. No. 1315) shows 'Accessory Dwelling Unit Detached' as Not allowed on Primary and Secondary Street frontages and by right only on Transitional and Residential frontages.

Attached and internal ADUs are allowed by right on the same terms as detached ones: Section 9.101H(1) does not distinguish between the two, and the glossary definition amended 2-11-2025 by Ord. No. 1315 expressly covers an ADU 'attached or detached from the principal structure.' Section 9.101H's gross floor area definition, lifted from the state regulation, counts basements, lofts and intermediate floored tiers toward the size cap while excluding crawl spaces, garage parking areas, attics and enclosed porches, so a basement conversion counts against the cap but a finished attic space does not. In the Downtown Creative District the Section 4.324 use table allows attached ADUs by right on Residential frontages, by right on upper floors on Primary Street frontages, and by right on the ground floor (not on a Primary Street) plus upper floors on Secondary and Transitional frontages.

Section 9.101H, Requirements 3 states the cap flatly: 'The size of an accessory dwelling unit shall be no more than half of the gross floor area of the principal dwelling or 900 square feet, whichever is smaller.' The section defines gross floor area itself, counting all stories of compliant ceiling height including basements, lofts and intermediate floored tiers, measured from interior faces of exterior walls, and excluding crawl spaces, garage parking areas, attics and enclosed porches; where a lot has multiple principal dwellings, the largest one's floor area sets the ceiling. Pittsfield sets no separate ADU height, setback or lot-coverage numbers. Instead Requirements 2 says ADU dimensional requirements 'shall follow the most permissive dimensional requirements that apply to either the principal dwelling, a single-family residential dwelling, or accessory uses in general,' which mirrors 760 CMR 71.03(3)(b)2. A height waiver is available by special permit under Requirements 4(b) if the applicant shows the structure is not substantially more detrimental to surrounding uses.

Nothing in Section 9.101H or the Section 2.2 glossary conditions an ADU on the owner living on the property, and the older 'accessory apartment' definition that predated the ADU framework was repealed 4-13-2021 by Ord. No. 1237. State law forecloses the requirement anyway: M.G.L. c. 40A, § 3 provides that the use of land or structures for a protected ADU 'shall not require owner occupancy of either the accessory dwelling unit or the principal dwelling,' and 760 CMR 71.03(2)(a) lists owner-occupancy as a Prohibited Regulation. One point of confusion worth flagging: Pittsfield's short-term rental section does use owner occupancy as a gate, but only for a second short-term rental unit, and that is a rule about short-term rentals rather than about ADUs.

Pittsfield's off-street parking schedule at Section 10.111 has no accessory dwelling unit row; it lists 'Dwellings-One Family' and 'Dwellings-Two Family' at 'One space for each dwelling unit.' Under Section 10.105, when a use is not specifically listed the Building Inspector applies the requirement for the most similar listed use, which points to one space for an ADU. State law then caps whatever the city applies: M.G.L. c. 40A, § 3 allows 'not more than 1 additional parking space' for an ADU and no additional space for one located within half a mile of a commuter rail station, subway station, ferry terminal or bus station, and 760 CMR 71.03(2)(b) sets the trigger generously, applying the zero-parking rule if any portion of the lot falls within a 0.5-mile radius of a transit station. 760 CMR 71.02 defines Bus Station broadly as 'A location serving as a point of embarkation for any bus operated by a Transit Authority,' so in a city with regional bus service the exemption reaches a lot of ground. Because Pittsfield never wrote an ADU parking rule of its own, confirm the applied number with the Building Inspector.

Section 9.101H, Requirements 1 is explicit: 'One ADU is permitted by right, subject to dimensional requirements of this section, in any property containing a one- or two-family residential use.' No special permit and no site plan review attaches to a first ADU; Pittsfield's site plan review triggers are use-specific (marijuana establishments, drive-throughs, large Downtown Creative District projects) and none reaches an ADU. The applicant simply pulls a building permit from the Building Inspector under Section 12.2, filing the plans required of a by-right (BR Group) use under Section 12.201, with a copy of the permit going to the Community Development Board. Each additional ADU on the same lot needs a special permit from the Zoning Board of Appeals, or from the Community Development Board inside the Downtown Creative District, under Requirements 4, which is also the route for a height waiver. That two-tier structure matches 760 CMR 71.03(5).

Nothing in Section 9.101H limits who may occupy or rent an ADU, and M.G.L. c. 40A, § 3 protects 'the use of land or structures for a single accessory dwelling unit, or the rental thereof.' Short-term use is a separate regime. Section 7.856, added 9-9-2025 by Ord. No. 1325, defines a short-term rental as a stay of no more than 30 days, caps any short-term rental at 150 total days per calendar year, requires the operator to register each unit with the City Clerk's Office and on the Massachusetts Department of Revenue short-term rental list, and requires an Administrative Site Plan Review by the Director of Community Development before the first registration issues. An owner may register only one short-term rental unit in Pittsfield unless the Community Development Board grants a special permit for a second, and that path requires the first unit to be a primary, owner-occupied one and the second to sit more than half a mile away if on a separate parcel. Short-term rentals are barred outright in income- or affordability-restricted units, are capped at one renter per 250 square feet up to 12 renters, and must supply one on-site parking space per 800 square feet. M.G.L. c. 40A, § 3 and 760 CMR 71.03(3)(c) expressly permit municipalities to restrict or prohibit short-term rental of protected ADUs, so these rules bind ADUs. Ord. No. 1325 also added Section 9.302J, which puts rentals under 31 days outside the home occupation rules.