ADU rules in Easthampton

A detached backyard ADU is permitted by right. Table 5-1 row 7 lists "Accessory Dwelling Unit" as P (Use Permitted by Right) in all eleven zoning districts, and section 8.55 says an accessory apartment in a new or existing detached accessory structure is permitted subject to standards, with no special permit and no site plan approval. The one gate that matters is section 8.53(a): the principal use on the lot must be a detached single- or two-family dwelling, which in practice confines detached ADUs to the six residential districts (R-5, R-10, R-15, R-35, R-40, R-80) plus lots elsewhere carrying a lawfully pre-existing nonconforming house. Only one ADU is allowed per lot under section 8.53(c). The ADU gets its own dimensional rows in Table 6-1 with no minimum lot area and a reduced rear setback (for example 15 feet front, 10 feet side, 10 feet rear in R-5; 30/15/15 in R-15; 50/25/25 in R-80).

Attached and internal ADUs are permitted by right on the same Table 5-1 row 7 "P" as detached units. Section 8.54 sets the standards for interior and attached units: a separate entrance meeting the state building code for safe egress, stairways to an upper-floor unit enclosed within the exterior walls (no egress stairs on the street-facing facade), and an addition to the principal dwelling allowed provided it meets the principal-structure height, setback and coverage limits in Tables 6-1 and 6-2. A basement or attic conversion inside the existing house is handled entirely by section 8.54 and needs only a building permit from the Building Commissioner. Section 8.56 further provides that alterations to a lawfully pre-existing nonconforming single- or two-family structure are permitted to create an ADU as long as they do not increase the nonconformity, with a Table 6-1 and 6-2 conformance safe harbor.

Section 8.55(b) caps new construction: "A new detached accessory dwelling unit (and/or an attached unit consisting of new construction) shall not exceed 900 square feet." Section 8.55(a) is deliberately more generous for reuse: an existing accessory structure may be converted or renovated into one new unit "regardless of its size or whether or not it conforms to the district's minimum setbacks as long as no changes in footprint or height are required." Section 8.54, which governs interior and attached conversions, sets no floor-area number, so a conversion carved out of the existing house is not textually reached by the 900 sq ft cap either; the Building Commissioner administers section 8.5 and makes that call. Height and bulk come from Table 6-2 for the district (40 feet and 3 stories in R-5 through R-35, 35 feet and 2 1/2 stories in R-40 and R-80), not from the 25-foot accessory-building cap in section 6.74, because section 8.55(c) measures a new or expanded ADU against the principal-structure limits.

Easthampton's ordinance still says yes, but state law makes it unenforceable in the ordinary case. Section 8.53(b), unamended 2021 text, reads: "The owner(s) of the detached single- or two-family dwelling shall occupy one of the units as their primary residence at the time of occupancy, except for bona fide temporary absences. A property containing an approved ADU may be sold to a new owner even if it is non-owner occupied." Since February 2, 2025, M.G.L. c. 40A, s. 3 has provided that 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 requirements as a Prohibited Regulation. So for the normal case, one ADU no larger than the smaller of 900 sq ft or half the principal dwelling's gross floor area, on a lot with a single-family house in R-5 through R-80, no owner occupancy may be required. The local clause still reads on configurations Easthampton allows but the state does not protect: an ADU accessory to a two-family dwelling (760 CMR 71.02 defines a Principal Dwelling as a structure containing not more than one dwelling unit), and a unit larger than the state's protected size, which section 8.55(a) permits without limit when an existing accessory structure is converted.

Section 8.53(e) requires "one off-street parking space for the accessory apartment in addition to one off-street parking space required for the principal dwelling," surfaced consistently in Table 10-3, which lists one space per ADU and simultaneously drops the one-family dwelling requirement from two spaces to "One (1) per dwelling in association with an Accessory Dwelling Unit." Net effect: two spaces on an ADU lot, the same total a plain single-family house owes. The space must be built of materials consistent with the existing driveway with vehicular access to it, and section 8.53(e) lets the Building Commissioner waive it "for bonafide reasons submitted in writing," giving a person with disabilities and someone who does not own a vehicle as examples. One space is exactly the state ceiling for a protected ADU outside transit radii, but 760 CMR 71.03(2)(b)(2) bars any additional space where any portion of the lot lies within a half mile of a Transit Station, and 760 CMR 71.02 defines Bus Station as "a location serving as a point of embarkation for any bus operated by a Transit Authority," which includes a regional transit authority stop. Near a transit stop the local space is preempted outright.

Administrative. Table 5-1 marks the ADU "P," Use Permitted by Right, in every district, which in Easthampton's key is distinct from PA (site plan approval by the Planning Board under section 12.9) and SP (special permit from the Zoning Board of Appeals under section 12.7). Section 8.52(a) puts the Building Commissioner in charge: "The Building Commissioner shall administer and enforce the provisions of this Section 8.5." Section 8.52(b) requires a building permit application with a floor plan of the ADU and the principal dwelling, elevations and a scaled site plan, with a surveyor's verification only when new work is within three feet of, or at, a required setback line. A special permit from the Zoning Board of Appeals is needed in only two situations: to waive any requirement of section 8.5 (section 8.57), and where alterations to a nonconforming single- or two-family structure would increase its nonconformity (section 8.56(b)). No occupancy is allowed until the Building Commissioner issues a certificate of occupancy (section 8.53(g)).

Renting the ADU long term is the stated purpose of the ordinance: section 8.51(a) is "Add inexpensive rental units to the housing stock to meet the needs of smaller households, both young and old." There is no lease-length minimum, tenant-relationship test or rental licence for long-term use. Two ownership rules apply: section 8.53(d) bars selling or transferring the ADU separate and apart from the principal dwelling, which must remain in common or single ownership, and section 8.53(b)'s owner-occupancy clause is preempted for protected ADUs (see that field). Short-term rental is newly and tightly regulated: Chapter 4, Article VI of the general City Ordinances, sections 4-50.1 to 4-50.9, adopted by the City Council on March 18, 2026, approved by the Mayor on April 8, 2026, and effective June 1, 2026, covers "the rental of a whole or a portion of a primary or accessory Dwelling Unit" for no more than 28 consecutive days. It requires annual registration with the Board of Health plus Department of Revenue registration, caps the city at 50 registered dwelling units with a waiting list, requires 365 days of prior ownership, limits an owner to one registration (two only if at least one is owner-occupied), allows one booking party at a time, mandates an annual joint building, fire and health inspection, requires one off-street space for the short-term rental plus one per dwelling unit on the parcel, and bans on-site advertising signs. Zoning Table 5-1 row 18, added the same day, lists Short-Term Rental as P in all districts "subject to registration and limitations set forth in City Ordinances" and "permitted only in conforming and lawful pre-existing nonconforming dwellings." M.G.L. c. 40A, s. 3 and 760 CMR 71.03(3)(c) expressly let municipalities restrict or prohibit short-term rental of protected ADUs, so this regime is not preempted.