The ADU bylaw published for Fairhaven is from 1998, and every requirement in it is void
Look up accessory dwelling units in the Fairhaven bylaw and you land on Sec. 198-32.1, which still reads [Added 5-8-1998 STM by Art. 28]. It is a 1998 dwelling-conversion bylaw, not an Affordable Homes Act ADU bylaw — and as applied to a protected-use ADU, every operative requirement in it is preempted.
Fairhaven’s own section is headed accessory dwelling units. On Sconticut Neck and in the village people say in-law apartment, or backyard apartment for a detached unit. All of them are protected uses under the state rules, whatever the 1998 text says.
Planning Board special permit. Lot must meet the greater of the Sec. 198-18 minimum or 22,500 sq ft. Unit not less than 1,000 sq ft. No expansion of the existing structure.
Take them one at a time against 760 CMR 71.03. A special permit cannot be required for a protected-use ADU. A minimum lot size greater than the district minimum cannot be imposed. And a minimum unit size of 1,000 square feet is not only preempted, it is incoherent against a 900-square-foot cap — read literally the published bylaw makes a compliant ADU impossible. Separately, the Attorney General deleted the 20-foot height limit in Sec. 198-32.1.C(1) in case 11677. The bylaw you will be shown is not the law that binds you.
What the Attorney General actually approved
Fairhaven did adopt a post-Act ADU bylaw — Article 13, partially approved 18 June 2025 in case 11677. The AG disapproved and deleted one provision:
- Height limit
- “No detached ADU shall exceed 20 feet in height, or be higher than the principal building, whichever is lower” — disapproved and deleted as more restrictive than the standards for principal dwellings.AG MLU case 11677, Art. 13; contrary to 760 CMR 71.03(3)(b)(2)
That deletion matters practically: a 20-foot cap rules out a second storey, and a second storey is often how you get 900 square feet onto a small Fairhaven lot without covering the yard. The cap is gone.
Fairhaven has the most generous accessory setback on our list
Five feet to any lot line, in every residential district — and because 760 CMR 71.03(3)(b)(2) lets a protected-use ADU take the more permissive of the accessory and principal rows, that five feet is what an ADU gets:
| District | Front (principal governs) | Side | Rear |
|---|---|---|---|
| RA | 20 ft | 5 ft | 5 ft |
| RB | 20 ft | 5 ft | 5 ft |
| RR | 30 ft | 5 ft | 5 ft |
| RC | 50 ft | 5 ft | 5 ft |
| AG | 50 ft | 5 ft | 5 ft |
Five feet against a principal side setback of 10, 20, 25 or 30 feet is an enormous difference, and it is why a detached unit is often achievable in Fairhaven where it would not be next door. Note the front yard is the exception — Fairhaven does not relax it, it forbids the accessory building there outright.
The grandfathering clause that is better than it looks
Most towns’ pre-existing lot protection covers area and frontage. Fairhaven’s Sec. 198-17C(1) exempts a qualifying lot from any increase in area, frontage, width, yard or depth requirements — yard included. So on a grandfathered lot the setbacks that apply are the ones in force when the lot was created, not today’s.
Sec. 198-17C(1)Qualifying means: not held in common ownership at recording or endorsement, conformed to the requirements then in force, and at least 5,000 square feet with 50 feet of frontage. A second route at Sec. 198-17C(2) covers lots conforming as of 1 January 1976 with at least 7,500 square feet and 75 feet of frontage.
Sec. 198-17C(1); Sec. 198-17C(2)The septic condition Fairhaven does impose
One requirement in the published section is not about zoning and does not go away: use of an existing on-site septic system to serve the proposed unit is permitted only upon approval of the Board of Health. That is a health-code condition, and 760 CMR 71.00 does not displace health codes.
Sec. 198-32.1D(4)So in Fairhaven the septic conversation happens with the Board of Health early, not late. Title 5 design flow is tested on the whole property’s bedroom count under 310 CMR 15.000. Planning ranges are in our cost guide.
Parking: the local schedule, and the state ceiling
Fairhaven’s local schedule asks two spaces for a dwelling unit with two or more bedrooms and one for a unit with fewer, and Sec. 198-32.1D(2) points ADU parking at that same schedule. The state rule caps it: no more than one additional space for a protected-use ADU where the whole lot is outside a half-mile radius of a Transit Station, and none where any part of the lot is inside one.
Sec. 198-27B(1); Sec. 198-32.1D(2); 760 CMR 71.02 and 71.03A two-bedroom ADU in Fairhaven therefore owes one space, not two, whatever the local schedule says.
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 Fairhaven Zoning Bylaw, Chapter 198 —
Sec. 198-32.1as published on eCode360 and downloaded 2 September 2026, still stamped [Added 5-8-1998 STM by Art. 28];Sec. 198-17C(1)and(2)(pre-existing lots);Sec. 198-18(dimensional table);Sec. 198-22A(3)and(4)(accessory buildings);Sec. 198-27B(1)(parking schedule). - Massachusetts Attorney General, Municipal Law Unit, case 11677, Art. 13, partially approved 18 June 2025 — the height limitation in
Sec. 198-32.1.C(1)disapproved and deleted as contrary to 760 CMR 71.03(3)(b)(2). - 760 CMR 71.00 and G.L. c.40A §3 as amended by the Affordable Homes Act — forbidding a special permit requirement, a minimum lot size above the district minimum, and a minimum unit size, as applied to a protected-use ADU.
- 310 CMR 15.000 (Title 5), and the Board of Health approval condition at
Sec. 198-32.1D(4), which the state ADU rules do not displace.
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.