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Can I build an ADU in Reading, Massachusetts?

Reading, Middlesex County · Bylaws checked 2026-10-20 · Reviewed · 17 cited sections

Allowed with a permit

Yes, but Reading's written zoning is out of date. The bylaw (§5.4.7, written in 2016-2017) allows an apartment inside an existing house by right, but requires a special permit for detached or new-construction units, owner occupancy, and a cap of 1,000 sq ft or one-third of the house. Massachusetts law since February 2, 2025 protects one ADU of up to 900 sq ft (or half the house) by right with no owner-occupancy rule, so those conflicting local rules may not apply. A PROPOSED update (not yet adopted) is headed to the November 9, 2026 Town Meeting.

Apartment inside an existing house (no added floor area)By right under the current bylaw [2]
Apartment in an existing accessory building, or new construction/additionSpecial permit under the current bylaw (state law may override) [2]
Number per lot1 [3]
Max size (current bylaw)Lesser of 1,000 sq ft or one-third of the main house's gross floor area [4]
Owner occupancy (current bylaw)At least one owner must live on site (state law may override) [5]
Occupants / bedrooms (current bylaw)Max 3 people, 2 bedrooms [7]
UtilitiesBoth units on public water and sewer [6]
PROPOSED max size (Oct 5, 2026 draft, not adopted)Lesser of 900 sq ft or one-half of the main house [10]
PROPOSED parking (not adopted)1 space; none if any part of the lot is within 0.5 mile of the Downtown Train Depot [11]

What the current bylaw says

Reading's Zoning Bylaw calls an ADU an "Accessory Apartment" [1]. The bylaw posted on the town site (April 2025) still has the 2016-2017 rules:

  • Inside the existing house, no added floor area: by right. In an existing accessory building, or in a new structure or addition: special permit [2]. The table says which apartment types are by right and which need a special permit; the use tables mark those as "SPA," a special permit from the Zoning Board of Appeals [16].
  • One apartment per lot, with its own kitchen and bath [3].
  • Size: no more than 1,000 sq ft or one-third of the main house, whichever is less [4].
  • Owner occupancy: at least one owner must live in the apartment or the main house [5].
  • Must be on public water and sewer [6]. No more than 3 occupants and 2 bedrooms [7]. Occupants must park off the street, and only one driveway is allowed [8]. A detached apartment can't sit between the house and the street [9].

State law may override parts of it

Since February 2, 2025, Massachusetts law protects one ADU per lot of up to 900 sq ft or half the house (whichever is smaller), attached or detached, by right. Towns can't require a special permit or owner occupancy, or more than one parking space. So Reading's special-permit, owner-occupancy and related limits may not apply to a protected ADU. The town's Building Division doesn't explain this. It just links the state ADU FAQ [12]. The town's own planning presentation says "Reading can no longer require a SP for ADUs" [13].

PROPOSED changes (not yet law)

The rules above come from the April 2025 bylaw. The Community Planning and Development Commission (CPDC) opened a hearing on September 14, 2026 and continued it to October 5, 2026 [15]. It is preparing amendments for the November 9, 2026 Subsequent Town Meeting. The October 5 draft would:

  • allow ADUs by right with a 900 sq ft / one-half cap [10];
  • drop owner occupancy, which the town says it can no longer require [17];
  • require 1 parking space, or none if any part of the lot is within 0.5 mile of the Downtown Train Depot [11];
  • bar ADUs from being used as short-term rentals [14].

This is a proposal only. Check whether Town Meeting adopted it.

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

Next steps

  1. Measure your house's gross floor area. Under state law a protected ADU can be up to 900 sq ft or half the house, whichever is smaller.
  2. Call the Building Division (781-942-6613) or the Planning Division/CPDC (781-942-6670). Ask how they currently handle protected ADUs, and whether the November 9, 2026 Town Meeting adopted the new ADU bylaw.
  3. Apply for a building permit online (OpenGov) with plans and a plot plan. Expect review by Building, Fire, Planning, Engineering and, near wetlands, Conservation (781-942-6616).
  4. Make sure both units can connect to public water and sewer.

Common questions

Can I build an ADU in Reading, Massachusetts?
Yes. Reading's zoning bylaw (April 2025) allows an apartment inside an existing house by right but requires a special permit for detached or new-construction units. State law since February 2, 2025 protects one ADU per lot by right, so those conflicting local limits may not apply.
How big can an accessory dwelling unit be in Reading, MA?
It depends on which rule applies. Reading's current bylaw caps an accessory apartment at the lesser of 1,000 sq ft or one-third of the main house. State law protects one ADU of up to 900 sq ft or half the house, whichever is smaller. The proposed update would use the 900 sq ft / one-half cap.
Does the owner have to live on the property to have an ADU in Reading, Massachusetts?
Reading's current bylaw says at least one owner must live in the apartment or the main house. But state law since February 2, 2025 bars towns from requiring owner occupancy for a protected ADU, so that rule may not apply. The pending proposal would drop it.
Is Reading, MA changing its ADU bylaw?
A proposal is pending, not adopted. The CPDC's October 5, 2026 draft goes to the November 9, 2026 Subsequent Town Meeting. It would allow ADUs by right up to 900 sq ft or one-half of the house, drop owner occupancy, require 1 parking space (none within 0.5 mile of the Downtown Train Depot), and bar short-term rentals in ADUs. Check whether Town Meeting adopted it.
Can I rent my ADU on Airbnb in Reading, Massachusetts?
Not decided yet. Under the pending proposal for the November 9, 2026 Town Meeting, ADUs could not be used as short-term rentals. That is a proposal only and isn't law unless Town Meeting adopts it.

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 Reading's published bylaws. Section numbers are as printed in the source.

  1. §2.0 Definitions, Accessory Apartment, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 6
    Accessory Apartment: A self-contained dwelling unit that is clearly subordinate to a primary dwelling unit on the same lot. An accessory apartment may be all or part of an accessory building or incorporated within a building that was originally used as a single family dwelling.
  2. §5.4.7.2 Restrictions (table of accessory apartment types, read row by row), Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 40
    Within Principal dwelling - No addition to gross floor area By Right Within Existing Accessory Building - No addition to gross floor area Special Permit required New structure or addition to gross floor area of existing structure Special Permit required
  3. §5.4.7.3.a, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 41
    a Only one (1) Accessory Apartment per lot may be created. The Accessory Apartment shall be a complete, separate housekeeping unit containing both kitchen and bath.
  4. §5.4.7.3.b, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    b An Accessory Apartment shall have a gross floor area not to exceed the lesser of 1000 square feet or one-third of the gross floor area of the Principal Single-Family Dwelling on the lot, exclusive of any garage, unfinished basement, shed or other accessory structure thereon.
  5. §5.4.7.3.c, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    c At least one (1) of the owners of a lot containing both a Principal Single Family Dwelling and an Accessory Apartment shall reside in either the Accessory Apartment or the Principal Dwelling.
  6. §5.4.7.3.h, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    h Both the Principal Single Family Dwelling and the Accessory Apartment shall be connected to the public water and sanitary sewer systems.
  7. §5.4.7.3.i, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    i An Accessory Apartment may not be occupied by more than three (3) people nor have more than two bedrooms.
  8. §5.4.7.3.g, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    Only one access driveway shall be permitted on a lot containing an Accessory Apartment unless the Board of Selectmen has authorized an additional access driveway.
  9. §5.4.7.3.k, Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 42
    k A Detached Accessory Apartment shall not be located between any exterior wall of a Principal Single Family Dwelling and any right-of-way (the “No Build Area”), unless it is created through the conversion of an accessory structure located within the No Build Area that was constructed or permitted prior to 2017, or through the preservation of a carriage house, stable or barn that was constructed or permitted prior to 2017; provided, however, that such conversion of an accessory structure or preservation of a carriage house, stable or barn for use as an Accessory Apartment shall not result in the addition of gross floor area to that portion of the structure that is within the No Build Area.
  10. CPDC presentation, slide 7 (Summary) - proposal, CPDC ADU Zoning Bylaw Public Hearing presentation, September 14, 2026 (proposed amendments), p. 7
    ADUs are allowed by-right in Single Family zoning districts. Lot size, lot coverage, and other dimensional requirements for ADUs cannot be more restrictive than requirements for any structures within these zones. Limited to 900 sf or ½ size of principal dwelling, whichever is less.
  11. PROPOSED §5.4.7.3 (Oct 5, 2026 draft) - parking, PROPOSED Zoning Bylaw ADU amendments - CPDC public hearing draft with track changes, October 5, 2026 (for the November 2026 Subsequent Town Meeting), p. 21
    c One (1) dedicated off-street parking space is required for an ADU located on a lot that is entirely outside a 0.5-mile radius of the Downtown Train Depot. No off-street parking is required for an ADU if any portion of the lot is within a 0.5- mile radius from the Train Depot.
  12. ADU - Accessory Dwelling Unit, Building Division - Permitting & Application Information (sheds/accessory structures, fences, pools, hot tubs, ADU, setbacks), p. 1
    ADU - Accessory Dwelling Unit Please refer to the Massachusetts State Website for Frequently Asked Questions
  13. CPDC presentation, slide 5 (What is Changing?), CPDC ADU Zoning Bylaw Public Hearing presentation, September 14, 2026 (proposed amendments), p. 5
    Require a special permit or other discretionary zoning approval for the use or rental of a protected use ADU. ⟶ Reading can no longer require a SP for ADUs.
  14. PROPOSED §5.4.7.2.c (Oct 5, 2026 draft), PROPOSED Zoning Bylaw ADU amendments - CPDC public hearing draft with track changes, October 5, 2026 (for the November 2026 Subsequent Town Meeting), p. 17
    c. Accessory Dwelling Units shall not be used as Short Term Rentals.
  15. CPDC draft minutes, Sept 14, 2026, CPDC draft minutes, September 14, 2026 (ADU Zoning Bylaw public hearing opened and continued to October 5, 2026), p. 3
    Mr. Manganiello made a motion to continue the Public Hearing to Monday October 5, and it was seconded by Ms. Clish.
  16. §5.2.1 (use table legend), Town of Reading Zoning Bylaw ('Zoning Bylaw - April 2025', last amended by the April 28, 2025 ATM Art. 16), p. 31
    In these tables, "Yes" denotes a use permitted by right in a particular district; the letters "SPA" denote a use permitted in a particular district only by Special Permit from the Zoning Board of Appeals;
  17. CPDC presentation, slide 5 (What is Changing?), CPDC ADU Zoning Bylaw Public Hearing presentation, September 14, 2026 (proposed amendments), p. 5
    Reading can no longer require an owner or family member live in ADU.
This page summarizes Reading's posted bylaws as of 2026-10-20. Bylaws are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with Building Division / Inspectional Services, Public Services Department (Building Inspector/Commissioner is the Zoning Bylaw enforcement officer, Zoning Bylaw s.4.2), Town Hall, 16 Lowell Street, Reading MA 01867 (Mon-Thu 7:00 AM-5:30 PM, closed Fridays); Permits Coordinator 781-942-6620; Conservation 781-942-6616; Public Health 781-942-9061; Planning/CPDC 781-942-6670 (781-942-6613) before you build. Spot an error?