Seekonk · South Seekonk · North Seekonk

Seekonk is the cleanest ADU town on the South Coast

Seekonk’s ADU article was approved in full by the Attorney General with no deletions — the only town on our list where that is true. No owner-occupancy requirement, no rental restriction, no parking schedule that reaches a house, and no local floor-area definition. Which means one thing most owners will care about: your basement counts.

An accessory dwelling unit in the bylaw, an in-law apartment in conversation, a backyard apartment when it stands on its own. Seekonk permits all three by right in R-1 through R-4 and in LCVD.

Approved in full · No deletions · AG MLU case 11626

Seekonk’s bylaw contains no definition of gross floor area or floor area at all.

With no competing local definition, 760 CMR 71.02 governs ADU sizing unopposed — including basement area at compliant ceiling height. That is a real difference. In a town whose local definition excludes basements, a walkout lower level is free floor area you cannot use toward the unit. Here it counts toward your 900 square feet, which means a compact footprint can reach the full cap.

Sec. 1.3 definitions, full-text search — and Sec. 1.3 ACCESSORY DWELLING UNIT (ii) adopts the state figure by reference

Where an ADU is allowed

Article 12 added the ADU definition at Sec. 1.3 and use-table line 5 at Sec. 4.2.3, permitting accessory dwelling units by right in R-1, R-2, R-3, R-4 and LCVD, and prohibiting them in LBD, HBD and I.

Sec. 4.2.3 Residential Uses, row 5; AG MLU case 11626, Art. 12

R-2 is the second column of the use table and reads Y — an as-of-right use, no special permit, no zoning board.

What Seekonk does not ask of you

Owner occupancy: Not required. No provision exists.Sec. 1.3 — no provision present
Rental restriction: None imposed by any ADU provision. The Sec. 1.3 definition carries the state proviso only.Sec. 1.3
Size cap: Half the gross floor area of the principal dwelling or 900 sq ft, whichever is smaller — the state figure, adopted by reference. No stricter local cap.Sec. 1.3 ACCESSORY DWELLING UNIT (ii)
Special permit on a nonconforming lot: Not required. See below.Sec. 4.3.2

One provision that does not reach ADUs, despite appearances

Sec. 4.3.3.4 imposes a no-short-term-rental condition on a single-family house built on an unmerged adjacent common-ownership lot. That is a different provision about a different situation and it does not reach accessory dwelling units. It is easy to find by search and easy to misread as an ADU rental restriction.

Parking: there is no schedule that reaches your house

This is worth understanding precisely, because it is unusual. Seekonk’s Sec. 8.1.3 parking schedule has exactly one residential row — “Residential Use subject to site plan review”, minimum 2 and maximum 2.5 per dwelling unit. And Sec. 2.8.3 exempts residential uses from site plan review. So no schedule row reaches an ordinary house or its ADU at all.

Sec. 8.1.3; Sec. 2.8.3

Even if a building official reads two spaces per unit into it anyway, 760 CMR 71.03 caps a protected-use ADU at one additional space. Do not concede more than one.

760 CMR 71.03(2)(b)

Nonconforming lots and houses: three separate reliefs

Seekonk carries more useful nonconforming relief than any other town on our list, and the three provisions do different jobs.

An accessory ADU on a nonconforming lot needs no special permit

The final sentence of the first paragraph of Sec. 4.3.2 says so expressly: the section “shall not be deemed to require a special permit to allow an accessory use or accessory structure on a non-conforming lot” — while all other dimensional and use requirements still apply. On an undersized Seekonk lot, that removes the zoning board from the path entirely.

Sec. 4.3.2, final sentence of the first paragraph

An attached or over-garage unit on a nonconforming house

Alteration, reconstruction, extension or structural change to a single- or two-family structure is exempt from Sec. 4.3 where it does not increase the nonconforming nature of the structure. That is the route for an over-the-garage or attached ADU on a house with an existing setback nonconformity — provided the addition does not push further into the deficient yard.

Sec. 4.3.3.2

And an R-4 route by right

In R-4 only, a pre-existing lot of record with at least 75% of the required frontage — 150 feet — meeting the footnote-3 alternate area may be extended or altered by right, with no zoning board special permit.

Sec. 4.3.2

Lot coverage: impervious, not footprint

Seekonk defines lot coverage as “the amount of any lot that is covered with artificial impervious surface” — impervious surface, not building footprint. That is broader than most towns, and it means a new driveway or parking area counts. But it only binds where a coverage figure exists at all, which is the business districts and the Water Resource Protection District groundwater zone. The residential rows carry no coverage figure.

Sec. 1.3 LOT COVERAGE

So on an ordinary Seekonk residential lot, coverage is not the constraint. Setbacks and septic are.

Undersized lots, and septic

Sec. 4.3.3.3 carries the standard c.40A §6 fourth-paragraph protection: increases in area, frontage, width, yard or depth do not apply to a lot for single- or two-family use that at recording was not held in common ownership with adjoining land, conformed to the requirements then in force, and has at least 5,000 square feet and 50 feet of frontage.

Sec. 4.3.3.3

Seekonk is substantially on private septic. Title 5 tests design flow on the whole property’s bedroom count, and whether your existing system carries the added bedroom is the number that decides the project. That is what we go and check. Planning ranges are in our cost guide.

310 CMR 15.000

We will tell you whether it works before you spend anything

Southcoast Building is an approved Feasibility Study Provider under the Massachusetts Housing Partnership ADU Incentive Program. A licensed builder walks your property, reads your parcel against the bylaw, checks the septic and the grading, and tells you whether an ADU works here and roughly what it would cost. Thirteen of our studies have been approved by MHP to date.

Request your free study

$0 to you under the MHP ADU Incentive Program · One study per property · Michael Bicho · (508) 269-2131

Where these figures come from

Town of Seekonk Zoning Bylaw, 2024 Recodification, stamped through the Town Meeting of 18 November 2024 — Sec. 1.3 (definitions, including ACCESSORY DWELLING UNIT and LOT COVERAGE), Sec. 2.8.3 (site plan review exemption), Sec. 4.2.3 (use table), Sec. 4.3.2, 4.3.3.2, 4.3.3.3, 4.3.3.4 (nonconforming), Sec. 8.1.3 (parking schedule).
Massachusetts Attorney General, Municipal Law Unit, case 11626, Art. 12, decided 27 May 2025 — approved in full, no deletions. Covers Arts. 11 and 12 of the 18 November 2024 Town Meeting, the same meeting the held recodification is stamped through.
760 CMR 71.00 — §71.02 gross floor area, governing unopposed here because Seekonk has no local definition; §71.03(2)(b) parking cap.
310 CMR 15.000 (Title 5) for the design-flow and bedroom-count test.

Zoning changes, and a building inspector’s reading of it is the one that governs your permit. Nothing here is a determination about your property. It is what the adopted text and the Attorney General’s decisions say as of 8 September 2026.