Town Permit Guide

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Can I build an ADU in Worcester, Massachusetts?

Worcester, Worcester County · Bylaws checked 2026-10-15 · Reviewed · 9 cited sections

Allowed with a permit

Yes. Since January 13, 2026, Worcester allows one accessory dwelling unit (ADU) per lot by right in all residential districts, attached, detached or inside the house, up to 900 sq ft. You need a building permit and a certificate of occupancy; the owner doesn't have to live on site, no extra parking is required, and the ADU can't be used as a short-term rental.

ApprovalBy right (building permit from Inspectional Services); no special permit unless you need dimensional or parking relief [2]
Number per lot1 ADU [4]
Max size900 sq ft gross floor area [4]
Attached or detachedDetached, attached, or internal to the main house [1]
Owner-occupancyNot required [8]
Extra parkingNone required (existing required spaces can't be removed) [6]
Short-term rentalNot allowed in an ADU [3]
Front yardNot allowed unless approved by the Building Commissioner [5]
Certificate of occupancyRequired before use [9]

Where ADUs are allowed

Worcester rewrote its ADU rules in Zoning Amendment 1494, ordained January 13, 2026, and the change is folded into the current zoning ordinance. An ADU is a self-contained unit with its own sleeping, cooking and sanitary facilities and a separate entrance, and it may be detached, attached, or internal to the main house [1]. ADUs are allowed by right as an accessory use in every district marked in Table 4.1 [2]. The ADU row of Table 4.1 [7] is a row of Y/N codes, one per district: it shows "Y" (allowed) in every residential district (RS-10, RS-7, RL-7, RG-5) and in every other district except IP-0.33 (industrial park), which is the table's only "N".

Size and placement

You can have one ADU per lot, up to 900 sq ft of gross floor area [4]. Setback and height rules for an ADU can't be stricter than those for a single-family house or an accessory structure in the same district, whichever is more permissive. An ADU inside an existing building with no addition is exempt from the Table 4.2 height limits. ADUs generally can't sit in the front yard unless the Building Commissioner approves it [5]. An ADU may be added to a lot or building that is nonconforming, as long as any addition meets the dimensional rules.

Occupancy, parking and rentals

The owner doesn't have to live on the property [8]. No extra off-street parking is required, but you can't remove parking the lot already needs, for example by converting a required garage space [6]. The ADU and the main house must stay on the same lot, and the ADU may not be a short-term rental as defined in M.G.L. c. 64G [3]. The city's guide adds that an ADU may not operate as a lodging house.

When you need a special permit

If your ADU can't meet the size, setback, height, front-yard or parking rules, the Planning Board can approve changes by special permit [6]. The city says this takes about 3 months and isn't guaranteed.

Permits

Apply for a building permit with a to-scale architectural plan and a site plan stamped by a Massachusetts registered land surveyor. The ADU needs a certificate of occupancy before anyone lives in it [9]. It also gets its own street address, and detached units usually need DPW sewer and water permits.

Worcester's rules appear consistent with the state ADU law shown below.

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

Next steps

  1. Check your zoning district and lot setbacks on the City's zoning map, and confirm whether the property is near wetlands, in a floodplain or in a local historic district (planning@worcesterma.gov).
  2. Hire a designer for to-scale architectural plans and a Massachusetts registered land surveyor for a stamped site plan showing setbacks.
  3. Request a street numbering slip (SNCA) for the ADU's new address, and contact DPW&P Engineering (dpwpermits@worcesterma.gov) about water/sewer connections; detached ADUs typically pay a $1,650-per-bedroom sewer connection fee.
  4. Apply for a building permit through the City's OpenGov portal (Inspectional Services, 25 Meade St., 508-799-1198); if you can't meet the dimensional or parking rules, get a Planning Board special permit first.
  5. Pass final inspection and obtain the certificate of occupancy before anyone moves in.

Common questions

Can I build an ADU in Worcester, MA?
Yes. Since January 13, 2026, Worcester allows one accessory dwelling unit per lot by right in all residential districts, whether attached, detached or inside the house. You need a building permit from Inspectional Services and a certificate of occupancy before use.
How big can an ADU be in Worcester, Massachusetts?
Up to 900 sq ft of gross floor area, with one ADU per lot. ADUs generally can't sit in the front yard unless the Building Commissioner approves it.
Does the owner have to live on site for an ADU in Worcester, MA?
No. Worcester doesn't require owner-occupancy for an ADU, and no extra parking is required, though you can't remove parking the lot already needs.
Can I Airbnb my ADU in Worcester, Massachusetts?
No. A Worcester ADU may not be used as a short-term rental, and the city's guide adds it may not operate as a lodging house.
When do I need a special permit for an ADU in Worcester, MA?
Only if your ADU can't meet the size, setback, height, front-yard or parking rules; then you need a Planning Board special permit before the building permit. Otherwise ADUs are by right.

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

  1. Art. IV, §8(G)(2) Definitions, City of Worcester Zoning Ordinance (ordained April 2, 1991, as amended through January 13, 2026), p. 118
    An ADU may be detached, attached, or internal to the Principal Dwelling.
  2. Art. IV, §8(G)(3), City of Worcester Zoning Ordinance (ordained April 2, 1991, as amended through January 13, 2026), p. 118
    Notwithstanding anything to the contrary in Article IV, Section 8A-F, Article V, or Article XVI, Section 4 of this Ordinance, Accessory Dwelling Units shall be allowed by right, as an accessory use, in all zoning districts as determined by Table 4.1, in accordance with the requirements set forth herein.
  3. Amendment 1494, §8(G)(4)(b), Zoning Amendment 1494 - Accessory Dwelling Units (ordained January 13, 2026), p. 2
    ADUs shall not be a “Short Term Rental” as defined in M.G.L. c. 64G sec. 1.
  4. Art. IV, §8(G)(5)(a), City of Worcester Zoning Ordinance (ordained April 2, 1991, as amended through January 13, 2026), p. 119
    There shall be no more than one (1) ADU per lot, in accordance with the following dimensional requirements: a) Size: The gross floor area of an ADU shall be no greater than nine hundred (900) square feet.
  5. Amendment 1494, §8(G)(5)(c), Zoning Amendment 1494 - Accessory Dwelling Units (ordained January 13, 2026), p. 3
    ADUs shall not be permitted within the front-yard, unless approved by the Building Commissioner through a reasonable analysis in accordance with the requirements of 760 CMR 71.03 (3).
  6. Amendment 1494, §8(G)(6)-(7), Zoning Amendment 1494 - Accessory Dwelling Units (ordained January 13, 2026), p. 3
    Parking: ADUs shall not require additional off-street parking spaces. However, the addition of an ADU shall not eliminate existing parking spaces that are otherwise required by this Ordinance from a lot (e.g., if an ADU is constructed in an existing parking facility).
  7. Table 4.1, Residential Uses, line 19, City of Worcester Zoning Ordinance (ordained April 2, 1991, as amended through January 13, 2026), p. 36
    19. Accessory Dwelling Unit (ADU) Y Y Y Y Y Y Y
  8. ADU Quick Guide, Use/Occupancy Restrictions, Accessory Dwelling Units (ADUs) - Quick Guide, p. 1
    The owner is not required to live on the property that has an ADU.
  9. Amendment 1494, §8(G)(4)(d), Zoning Amendment 1494 - Accessory Dwelling Units (ordained January 13, 2026), p. 2
    ADUs shall obtain a certificate of occupancy prior to commencement of use.
This page summarizes Worcester's posted bylaws as of 2026-10-15. Bylaws are amended, and individual lots can have overlays, subdivision covenants, or HOA rules that are stricter. Confirm with Department of Inspectional Services - Building & Zoning, 25 Meade Street (508-799-1198) before you build. Spot an error?