Holbrook · Plymouth County line

Nobody can tell you what Holbrook’s ADU bylaw says — including us

The Holbrook zoning bylaw available to read was last amended at the Special Town Meeting of 11 September 2019. That is five years before the Affordable Homes Act created the ADU entitlement. It contains no accessory dwelling unit provision, and that absence proves nothing at all about where Holbrook stands today.

The state calls it an accessory dwelling unit. You may be planning an in-law apartment for a parent or a backyard apartment for a grown child. Holbrook’s published bylaw names none of the three.

Highest published-code lag in our zoning library

The registered Holbrook bylaw is dated 11 September 2019 and predates the Affordable Homes Act entirely. Its zero ADU hits therefore prove nothing.

Full-text search of the held 2019 edition; AG MLU ADUS index checked 2 September 2026

Most towns on this site have a published-text problem of some kind — a struck-down clause still printed, a bylaw adopted but not codified. Holbrook’s is the largest: the document is roughly seven years old and older than the law itself. Two Attorney General decisions with blank topics postdate the Act and have not been opened, so Holbrook may well have adopted an ADU bylaw we have not seen. Anyone quoting you a Holbrook ADU figure off the published text is quoting a document written before the entitlement existed. We will not do that.

What we can tell you, and it is not nothing

760 CMR 71.00 sets a floor that Holbrook cannot go below, whatever its own bylaw turns out to say. On a single-family lot that means:

Permission: One protected-use ADU as of right in any district permitting single-family dwellings, whether as of right or by special permit. No local provision can require a special permit for it.760 CMR 71.03
Size: 900 sq ft or half the gross floor area of your house, whichever is smaller — basement area at compliant ceiling height included.760 CMR 71.02
Parking: Not more than one additional space, and none at all where any part of the lot sits within a half mile of a Transit Station.760 CMR 71.03(2)(b)
Dimensional standards: A town may not impose standards on a protected-use ADU stricter than those for a principal dwelling. This is the provision that has struck down height caps and setback cross-references in half a dozen towns nearby.760 CMR 71.03(3)(b)(2)

So a Holbrook project is not blocked. It is a project where the first working session is spent at the Town Clerk’s office reading the adopted text rather than at a desk reading a website.

Working on an older house — two routes, and one is much cheaper

This part of the Holbrook bylaw we have read, and the difference between the two routes is worth real money.

The Building Commissioner route

A determination by the Building Commissioner, available where the gross floor area increase is not more than 100%, on either an insufficient-area or an insufficient-frontage lot, provided the work complies with current setback, yard, coverage and height requirements. No zoning board, no hearing.

Sec. 5.5

The variance route

A variance is required where the work extends an exterior wall along the same nonconforming distance within a required yard — that is, continuing an existing wall on a line it already sits on. Many owners assume that is the safe design because nothing moves closer to the boundary. In Holbrook it is the expensive one.

Sec. 5.4

Which side of that line your design falls on is a drawing decision, and it is worth making deliberately at the sketch stage rather than discovering it at the counter.

How we would run a Holbrook file

In order, because skipping the first step makes every later number unreliable:

1. Read the adopted text: At the Town Clerk’s office — the current bylaw and any zoning articles adopted since September 2019, with their Attorney General decisions.Us, before anything is designed
2. Open the two AG decisions: The two blank-topic decisions postdating the Affordable Homes Act, to see whether either concerns ADUs.Us
3. Establish the district: And whether single-family is permitted there as of right or by special permit — either satisfies the 760 CMR 71.02 gate.Us
4. Septic and design flow: Title 5 tests the whole property’s bedroom count. Whether your existing system carries the added bedroom is usually what decides the project.Us, on the site visit

That first step is the whole difference between a Holbrook quote you can rely on and one built on a document from 2019.

310 CMR 15.000 for the design-flow test

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 Holbrook Zoning Bylaw, held edition last amended at the Special Town Meeting of 11 September 2019 — Sec. 5.4 and Sec. 5.5 (nonconforming structures). Searched in full: zero occurrences of “accessory dwelling”.
Massachusetts Attorney General, Municipal Law Unit, ADUS topic index checked 2 September 2026 — no Holbrook ADU decision exists, but two decisions with blank topics postdate the Affordable Homes Act and have not been opened.
760 CMR 71.00 — the operative floor in Holbrook until the adopted text is read: §71.02 definitions and size, §71.03 as-of-right permission and parking, §71.03(3)(b)(2) on dimensional standards.
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.