Town Permit Guide

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Can I build an ADU in Natick, Massachusetts?

Natick, Middlesex County · Bylaws checked 2026-10-19 · Reviewed · 8 cited sections

Allowed with a permit

Yes. Natick allows one ADU per lot as of right in its single-family districts. You file an ADU Application Review and get a building permit. The ADU can be attached or detached and can be no larger than half the main home's floor area or 900 sq ft, whichever is smaller. Neither the ADU nor the main house may be used as a short-term rental.

AllowedOne ADU per lot, as of right (M.G.L. c. 40A, §3) [1]
Max sizeHalf the main home's floor area or 900 sq ft, whichever is smaller [2]
Short-term rentalNeither the ADU nor the main house may be used as a short-term rental [3]
Lot conditionsLot must meet the district's maximum building coverage; the main house must be the only dwelling unit on the lot [4]
Detached ADU spacingAt least 10 ft from other structures; not between the road and the house's frontage [6]
Parking1 off-street space if the lot is 1/2 mile or more from a commuter rail station [7]
Two or more ADUsZBA special permit (super-majority vote) [8]

Allowed as of right

Natick's zoning bylaw (Sec. III-M, last amended at the October 28, 2025 Fall Town Meeting) says ADUs are permitted as of right under M.G.L. c. 40A, §3, in the single-family districts [1]. An ADU is a self-contained unit with its own sleeping, cooking and bathroom facilities and a separate entrance. It can be no larger than half the main home's floor area or 900 sq ft, whichever is smaller [2]. It can be attached or detached. We found no requirement that the owner live on the property.

Conditions

  • The lot must meet the district's maximum building coverage, and the main house must be the only dwelling unit on the lot before the ADU is added [4].
  • Neither the ADU nor the main house may be used as a short-term rental (under 31 days) [3]. The ADU can't be split onto its own lot or sold separately as a condo.
  • A detached ADU must be at least 10 ft from any other structure and can't sit between the road and the front of the main house [6].
  • You need one off-street parking space if the lot is 1/2 mile or more from a commuter rail station [7]. State law also bars parking requirements near bus and ferry stations. Natick's rule names only commuter rail, so state law may override it for a lot near a bus station.

Which review you get

The ADU Rules and Regulations (revised July 20, 2026) sort ADUs into four types [5]:

  • Type 1 (Building Commissioner, with the building permit): inside the house or an existing attached garage with no exterior expansion, in an existing detached garage more than 10 ft from the house, or built at the same time as a new house.
  • Type 2 (Building Commissioner ADU Site Review, as of right): a new detached ADU within the buildable envelope, or an addition that needs no zoning relief.
  • Type 3 (ZBA Section 6 finding): the lot or building is pre-existing nonconforming. This review is still as of right, by majority vote, with notice to abutters within 300 ft.
  • Type 4 (ZBA special permit): a second ADU on a lot [8], or a building that exceeds lot coverage or other dimensional limits.

Every ADU starts with an ADU Application Review filed in OpenGov. Departments review it, and the Building Commissioner issues a determination letter. You then have one year to apply for the building permit.

See how Natick compares with 8+ other Massachusetts towns on accessory dwelling units (adus) →

Next steps

  1. Gather the main home's gross floor area, a certified plot plan showing the ADU, entrances, walkways and parking, an ADU dimensional table, and a scaled map showing the distance to the West Natick or Natick Center commuter rail station.
  2. File an ADU Application Review in the Town's OpenGov portal and pay the review fee once the filing is found complete.
  3. Use the Building Commissioner's Determination Letter to learn your ADU type (1-4) and whether you need a ZBA Section 6 finding or special permit.
  4. Apply for the building permit in OpenGov within one year of the determination letter. Questions go to the Building Department, 508-647-6450.

Common questions

Are ADUs allowed in Natick, Massachusetts?
Yes. Natick allows one accessory dwelling unit per lot as of right in its single-family districts. You file an ADU Application Review, then apply for a building permit.
How big can an ADU be in Natick, MA?
An ADU in Natick can be no larger than half the main home's floor area or 900 sq ft, whichever is smaller. It can be attached or detached.
Can I Airbnb my ADU in Natick, Massachusetts?
No. Natick's zoning says neither the ADU nor the main house may be used as a short-term rental, meaning stays under 31 days.
Does an ADU need parking in Natick, Massachusetts?
It depends on location. Natick requires one off-street space if the lot is 1/2 mile or more from a commuter rail station. Natick's rule names only commuter rail, so state law may override it for a lot near a bus station.
Do I need a special permit for an ADU in Natick, Massachusetts?
Usually no. A single ADU is as of right, reviewed by the Building Commissioner or, on pre-existing nonconforming lots, by the ZBA. A ZBA special permit is needed for a second ADU or a building that exceeds lot coverage or other dimensional limits.

Massachusetts' statewide ADU law

Since February 2, 2025, the Affordable Homes Act (St. 2024, c. 150, §8) has protected one accessory dwelling unit (ADU) per lot in any zoning district that allows single-family homes (M.G.L. c. 40A, §3). Your town cannot ban it, require a special permit or other discretionary approval, or "unreasonably restrict" building or renting it.

What counts as a protected ADU:

  • A self-contained unit with its own sleeping, cooking and bathroom facilities, on the same lot as the main home.
  • No larger than 900 sq ft or half the main home's floor area, whichever is smaller.
  • It can be attached or detached, and it needs a separate entrance that meets the building code.

What towns cannot require:

  • That the owner live in the main home or the ADU.
  • More than 1 extra parking space, or any extra space if the lot is within 0.5 miles of a subway, commuter rail, ferry or bus station.
  • A minimum lot size, caps on the number of ADUs, or limits on who may live there (age, income, relationship).

What towns can still do: use reasonable site plan review, setback, height and bulk rules, require Title 5 septic compliance, and restrict or ban short-term rentals of ADUs. A second ADU on the same lot needs a special permit. State regulations at 760 CMR 71.00 (in effect since January 31, 2025) explain which rules count as unreasonable.

State sources: M.G.L. c. 40A, §3 (protected ADU paragraph) · M.G.L. c. 40A, §1A (ADU definition) · EOHLC, Accessory Dwelling Units (law, FAQ, 2026 draft regulations) · 760 CMR 71.00, Protected Use Accessory Dwelling Units

What the bylaw says

Exact text from Natick's published bylaws. Section numbers are as printed in the source.

  1. Sec. III-M.2.a, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 119
    a. ADUs are permitted As of Right per Massachusetts General Laws (MGL), Chapter (c) 40A, § 3.
  2. Sec. 200 Definitions, Accessory Dwelling Unit (ADU), Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 10
    (ii) is not larger in floor area than half (1/2) the floor area of the Principal Residential Dwelling or nine-hundred (900) square feet, whichever is smaller;
  3. Sec. III-M.3.b, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 119
    b. Neither the Principal Residential Dwelling nor the ADU shall be used as a Short-term Rental.
  4. Sec. III-M.3.a, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 119
    a. In order to qualify for an As of Right ADU, the Principal Residential Dwelling and the Lot shall: i. conform to the maximum Building Coverage of the respective Zoning District, per § IV-B Intensity Use Regulations of these Zoning Bylaws; and ii. be the only residential Dwelling Unit on the Lot prior to construction of the ADU.
  5. Section IV Permitting Classifications, Accessory Dwelling Units (ADU) Rules and Regulations (effective Feb 2, 2025, revised July 20, 2026), p. 4
    Natick has four (4) ADU permitting classifications, which are outlined in § III- M.4 Accessory Dwelling Unit Bylaw of the Natick Zoning Bylaws and outlined below for reference.
  6. Sec. III-M.5.c-d, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 121
    c. An ADU detached from the Principal Residential Dwelling shall be a minimum of ten (10) feet from another Structure on the Lot, per the State Building Code. d. A detached ADU shall not be located between a roadway and the designated frontage of the Principal Residential Dwelling.
  7. Sec. III-M.5.e, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 121
    e. An ADU shall provide one (1) off-street parking space on the Lot when located a half (1/2) mile or more from a commuter rail station.
  8. Sec. III-M.4.d, Zoning Bylaws (June 2026 edition, includes amendments through 2025 Fall Annual Town Meeting), p. 120
    The ZBA shall be the Special Permit Granting Authority (SPGA) for the following Special Permits, which shall require a super-majority vote: i. The creation of two (2) or more ADU per Principal Residential Dwelling or Lot, which will require a super-majority vote.
This page summarizes Natick's posted bylaws as of 2026-10-19. Bylaws are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with Building Department, Community & Economic Development (Building Commissioner / Chief Zoning Officer David G. Gusmini), Town Hall 2nd Floor, 13 East Central Street, Natick MA 01760 (508-647-6450) before you build. Spot an error?