ADU Rules by Town
All 25 North Shore Massachusetts municipalities we track, side by side — permit path, size cap, parking, energy code, and short-term rental limits.
Since the Affordable Homes Act took effect, most of what homeowners assume varies from town to town does not. The size cap, the ADU types allowed, the parking limit, and the owner-occupancy question now have the same answer in every municipality below, because 760 CMR 71.00 sets them at the state level and a local bylaw cannot go under that floor.
What still varies is narrower, and this page is built around it: which towns add a review step before the building permit, which energy code tier applies, whether the parking requirement is waived near transit, and whether short-term rental is off the table. Each municipality links to its full page, with the local bylaw citation and the contact for the department that issues the permit.
The Same in Every Town
State law did the work here. These are not our summaries of a local bylaw — they are counts across all 25 town files, recomputed every time the site builds.
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900 sq ft ceiling
Or 50% of the principal dwelling's gross floor area, whichever is smaller. No town on the North Shore sets a lower by-right cap.
25 of 25
All three ADU types
Detached, attached, and internal conversions are all permitted. Local bans on detached units were preempted by state law.
25 of 25
One parking space, at most
A town cannot require more than one space for a protected ADU, and near transit it cannot require any.
25 of 25
No owner-occupancy rule
You do not have to live on the property to have an ADU on it. Older bylaws that say otherwise are preempted.
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Every residential district
The protection is not limited to one or two zones — it reaches single-family residential districts across the municipality.
What Actually Varies
Six things, and every one of them changes either your schedule or your budget.
Permit path
23 municipalities issue the building permit directly. 2 run site plan review first — still administrative, but scheduled around a board's meeting nights, which is where weeks go.
Energy code tier
4 on the Specialized Opt-in Code, 18 on the Stretch Code, 3 on the base code. This is the single biggest town-to-town swing in what an ADU costs to build.
Parking near transit
19 of 25 waive the parking requirement for a unit within half a mile of a transit station. On a tight lot that exemption can be the difference between a workable site plan and no ADU at all.
Short-term rental
14 prohibit short-term rental of the unit outright. The rest are silent in the bylaw, which is not the same as permission — check before you count on that income.
Historic district review
5 apply historic district review. It is the one place the state regulation lets a town hold an ADU to stricter design standards than the house it sits behind.
What the town calls it
7 municipalities use their own term in the bylaw — AADU, Accessory Apartment, EFLA, FALA, and PADU. Searching the zoning code for "ADU" in those towns turns up nothing.
All 25 Municipalities
Sort any column, filter by permit path or energy code tier, or search by name. Every municipality name links to its full page — bylaw citation, districts, contacts, and the questions homeowners ask there.
Showing 25 of 25 municipalities
Where This Data Comes From
Each row is read from that municipality’s own zoning bylaw or ordinance, with the source link on the town’s page. All 25 are in Essex County. Most recent verification: 2026-02-26. Bylaws change at annual town meetings, which on the North Shore fall between April and June, so a page verified before the spring meeting may not reflect a change made at it. Where our reading of a bylaw is less certain — a draft article, an ordinance we could not confirm against an official posting — the town page says so rather than presenting a guess as fact. Nothing here is legal advice or a substitute for a conversation with your building department.
Next Steps
Once you know what your town allows, the next three questions are what it costs, how long it takes, and which type of unit fits your lot.
ADU Rules Across the North Shore
Which North Shore Massachusetts towns allow ADUs?
All 25 municipalities on this page allow accessory dwelling units. That is not a coincidence of local politics — the 2024 Affordable Homes Act and the regulation that implements it, 760 CMR 71.00, make a Protected Use ADU allowed by right in single-family residential zoning districts statewide. A town can still set reasonable dimensional and design standards, but it cannot decide to opt out.
Do any North Shore towns still require a special permit for an ADU?
None of the 25 municipalities we track require a special permit for a first Protected Use ADU — 23 issue the building permit directly. Boxford and Middleton run site plan review before the building permit issues, which is an administrative review rather than a discretionary approval and a lower bar than a special permit. Two narrow exceptions survive in the regulation itself: a second ADU on the same lot does require a special permit under 760 CMR 71.03(5), and a town may require one in a floodplain or aquifer protection overlay under 71.03(6) if it requires one for the principal dwelling.
How big can an ADU be on the North Shore?
24 of the 25 municipalities apply the state ceiling: 900 square feet or 50% of the gross floor area of the principal dwelling, whichever is smaller. The second half of that rule catches people out — on a 1,400 square foot house the by-right ceiling is 700 square feet, not 900. A larger unit is not necessarily forbidden, but it falls outside the protected-use path and back into ordinary local zoning.
Do I have to add parking for an ADU?
Not much of it. Every municipality on this page caps the ADU parking requirement at one space, and in 19 of 25 the requirement is waived entirely for a unit within half a mile of a transit station. The town column in the table above shows which rule applies where.
Can I rent my ADU on Airbnb?
14 of the 25 municipalities prohibit short-term rental of an ADU outright. The remainder do not address it in the bylaw text we verified, which is not the same as permission — a general local short-term rental ordinance, a condominium document, or a deed restriction can still apply. If short-term rental income is part of your plan, confirm it with the building or planning department before you build, not after.
Does my town require me to live on the property?
No. 25 of 25 municipalities impose no owner-occupancy requirement on an ADU. Several North Shore bylaws still contain owner-occupancy language on the books, but 760 CMR 71.03 preempts it for a Protected Use ADU. Where a town page notes a preempted provision, that is what it means: the words are still in the bylaw, but they are no longer enforceable against a protected unit.
Which towns have the strictest energy requirements for a new ADU?
Beverly, Newburyport, Salem, and Swampscott have adopted the Specialized Opt-in Code, the most demanding of the three tiers under 225 CMR 22.00. 18 of the 25 municipalities are on the Stretch Energy Code and 3 remain on the base code. The tier matters to your budget, not just your paperwork: a stricter tier means a tighter envelope, better equipment, and third-party verification by a rater. Our energy code guide explains what each tier requires.
What if my property is in a historic district?
Boxford, Hamilton, Ipswich, Nahant, and Wenham apply historic district review to ADU projects. Historic districts are the one place 760 CMR 71.00 expressly allows a town to hold an ADU to stricter design and dimensional standards than it would apply to the principal dwelling. The unit is still allowed; the exterior design review is simply a real step in the schedule, so it belongs in the plan from the start rather than as a surprise in month three.
Sources
Statewide statements on this page come from the following official sources. Each municipality’s own bylaw citation is on its town page.
- 760 CMR 71.00: Protected Use Accessory Dwelling Units — Mass. EOHLC
- Accessory Dwelling Unit (ADU) FAQs — Commonwealth of Massachusetts (EOHLC)
- 225 CMR 22.00: Massachusetts Stretch Code and Specialized Code for low-rise residential — Mass. DOER
- Municipal opt-in specialized code and stretch code adoption — Mass. DOER
Know Your Town's Rules. Now Build It.
We build ADUs across the North Shore and handle the permitting in every town on this page. Call for a free site visit and an honest read on what your lot can take.