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ADU Rules in Medford, Massachusetts

Complete guide to building an Accessory Dwelling Unit in Medford — zoning, setbacks, permits, costs, and more.

Max Size: The smaller of 900 sq ft or half the principal dwelling's gross floor area. Medford § 94-8.2.3(4) and M.G.L. c. 40A § 1A / 760 CMR 71.02 agree on the number. Under 760 CMR 71.02, GFA counts every story of compliant ceiling height including basements and lofts but excludes crawl spaces, garages, attics and enclosed porches — so a 1,400 sq ft house gets a 700 sq ft unit. § 94-8.2.3(4) lets the Board exceed 900 sq ft only for a carriage house or barn with preservation value, by special permit. Setbacks: 3 ft for a detached ADU, or 1 ft with fire-resistance-rated wall assemblies (§ 94-4.3.2(3), accessory structures). A dwelling needs a 15 ft rear yard (Table B, row 1), but 760 CMR 71.03(3)(b)(2) gives the ADU the more permissive of the two. An accessory building may occupy up to 25 percent of the rear yard (§ 94-4.2.5(1)) and must sit at least 10 ft from the house and from any other accessory building (§ 94-4.1.2(3)(a)). Parking: 1 Space Verified: 2026-09-20

Researched by ADU Zoning Hub · verified 2026-09-20 against Medford planning code and Massachusetts ADU law · methodology · 22 sources cited ↓

ADU Score: 7/10
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Are ADUs allowed in Medford, MA? [1][2][3][4][5][6][7]

Yes. Medford allows ADUs on most residential lots. A detached unit can be up to 900 sq ft, set 3 ft back from the rear line. One off-street space is required. Owner-occupancy is not required, so the unit can be rented out. A building permit is required and applications are reviewed through the standard permit process.

Maximum sizeThe smaller of 900 sq ft or half the principal dwelling's gross floor area. Medford § 94-8.2.3(4) and M.G.L. c. 40A § 1A / 760 CMR 71.02 agree on the number. Under 760 CMR 71.02, GFA counts every story of compliant ceiling height including basements and lofts but excludes crawl spaces, garages, attics and enclosed porches — so a 1,400 sq ft house gets a 700 sq ft unit. § 94-8.2.3(4) lets the Board exceed 900 sq ft only for a carriage house or barn with preservation value, by special permit.
SetbacksRear 3 ft for a detached ADU, or 1 ft with fire-resistance-rated wall assemblies (§ 94-4.3.2(3), accessory structures). A dwelling needs a 15 ft rear yard (Table B, row 1), but 760 CMR 71.03(3)(b)(2) gives the ADU the more permissive of the two. An accessory building may occupy up to 25 percent of the rear yard (§ 94-4.2.5(1)) and must sit at least 10 ft from the house and from any other accessory building (§ 94-4.1.2(3)(a)). · Side 3 ft from the side lot line for a detached ADU, or 1 ft with fire-resistance-rated walls (§ 94-4.3.2(3)) — more permissive than the 7½ ft side yard Table B requires of the house, so it governs under 760 CMR 71.03(3)(b)(2). § 94-4.3.2(1): in residential districts no accessory structure may stand in the required front or side yard, so a detached unit belongs in the rear yard. An attached ADU takes the house's own 7½ ft side yard.
ParkingUsually none; at most one space. § 94-8.2.3(7) asks for "no more than one additional parking space, when necessary and feasible"; 760 CMR 71.03(2)(b) caps it at one and bars any space if any part of the lot is within 0.5 mile of a Transit Station, which 760 CMR 71.02 defines to include a Bus Station — any embarkation point for an MBTA bus. Wellington, Medford/Tufts, Ball Square and West Medford stations and the bus network cover most of the city; Table A's 2 spaces per unit binds the house only.
Owner-occupancyNot required. § 94-8.2.3(2) still demands an affidavit that one of the two units is owner-occupied, and § 94-8.2.3(8) expires the permit every five years without a fresh affidavit; the Building Department's ADU handout (September 7, 2022, still posted) repeats both. State law overrides them: M.G.L. c. 40A § 3 bars owner-occupancy requirements, 760 CMR 71.03(2)(a) lists them first among Prohibited Regulations, and 71.03(4) bars enforcing such a condition even if imposed before January 31, 2025.

Do I need a permit to build an ADU in Medford? [8][9][10][11][12][13][14][15]

Yes. Every ADU in Medford needs a building permit. Review process: Building permit, filed online through the Citizenserve portal linked from the Building Department page (building, plumbing and gas, electrical and sheet-metal permits are all filed there; no work may start until the permit card is issued). No special permit and no hearing for one ADU: § 94-8.2.2 still reads "as of right in an existing principal dwelling or by special permit from the community development board (the SPGA) in an existing detached structure," but M.G.L. c. 40A § 3 forbids a special permit or other discretionary approval for a single ADU and 760 CMR 71.03(2)(e) bars requiring the unit to be attached or detached. Expect to file the § 94-8.2.3(1) plot plan (building, proposed unit, any septic system and parking; a mortgage inspection survey suffices). Zoning questions must go to the Building Commissioner in writing; Appendix A of the Code lists a $50 fee for a review or letter of legal zoning status. Building/Zoning Department, City Hall Room 115A, (781) 393-2509; Planning, Development & Sustainability, Room 308, (781) 393-2480, ocd@medford-ma.gov..

Permit fees$15.00 per $1,000 of estimated construction cost plus a $35.00 application fee, a $100.00 plan review fee for 1-4 family dwellings and $125.00 for a certificate of occupancy (Schedule of Building Fees effective July 28, 2009; Code Appendix A, § 10-35) — about $3,885 on a $250,000 ADU.
Typical timelineThe Building Department's FAQ says the building official has 30 days to review and act on a building permit application and that most reviews finish sooner; new buildings go to the weekly Tuesday development meeting for multi-department sign-off. No ADU-specific timeline is published.
Official Medford links:

Three things to know before you build in Medford

  • Print two things before you go to the counter: M.G.L. c. 40A § 3 and 760 CMR 71.03. Medford's ordinance and the Building Department's 2022 handout both still describe a special permit, an owner-occupancy affidavit and a five-year expiry, and none of the three survives the state law
  • Do the half-GFA arithmetic first. The cap is the smaller of 900 sq ft and half your house's gross floor area, so any house under 1,800 sq ft cuts you below 900 — and attics, crawl spaces, garages and enclosed porches do not count toward the house's GFA under 760 CMR 71.02
  • Use the accessory-structure setbacks, not the house's. Medford asks 15 ft at the rear and 7½ ft at the side for a dwelling but only 3 ft for an accessory structure (§ 94-4.3.2(3)), and 760 CMR 71.03(3)(b)(2) entitles you to whichever standard is more permissive. Leave the 10 ft between the house and the cottage that § 94-4.1.2(3)(a) requires, and keep the unit out of the front and side yards

Last verified 2026-09-20 against Medford planning code. How we verify

Yes — you can build one ADU in Medford by right, but the right comes from state law, not from the city's own text. Medford Zoning Ordinance § 94-8.2 (unchanged since Ord. No. 867 of March 22, 2022, and still unchanged in the city's consolidated ordinance dated April 28, 2026) allows an ADU as of right only inside an existing house, requires a Community Development Board special permit for a detached structure, and demands an owner-occupancy affidavit with a five-year expiry. All three conditions are superseded by M.G.L. c. 40A § 3 and 760 CMR 71.00 (effective January 31, 2025), which make a single ADU of up to 900 sq ft or half the house's gross floor area a protected use in every district where a single-family house is permitted (SF-1, SF-2, GR, APT-1 and APT-2), with no owner occupancy and no parking space where any part of the lot is within half a mile of a transit station or MBTA bus stop. The Building Department still posts its September 2022 ADU handout, so bring the statute and the regulation to the counter. Building permit fees are $15 per $1,000 of construction cost plus a $35 application fee.

Zoning & Size Requirements [1][2][3][4][5][6][7]

Yes — Medford allows ADUs. A detached ADU can typically be up to 900 sq ft under current Massachusetts and Medford zoning rules.

See what this means for your lot — ask Medford ADU builders for a quote →

Allowed ZonesSF-1, SF-2, GR, APT-1 and APT-2 — every district where a detached single-family dwelling is a permitted use (Table A, row A.1). 760 CMR 71.02 defines a "Single-family Residential Zoning District" as any district where single-family dwellings are permitted or allowable, so the protection is not confined to SF-1 and SF-2. None arises in ROS, APT-3, C-1, C-2, I, O, O-2, MUZ or the new Mystic Avenue, Salem Street and Medford Square districts (single-family is N there). Confirm at (781) 393-2480.
Max Size (Detached)The smaller of 900 sq ft or half the principal dwelling's gross floor area. Medford § 94-8.2.3(4) and M.G.L. c. 40A § 1A / 760 CMR 71.02 agree on the number. Under 760 CMR 71.02, GFA counts every story of compliant ceiling height including basements and lofts but excludes crawl spaces, garages, attics and enclosed porches — so a 1,400 sq ft house gets a 700 sq ft unit. § 94-8.2.3(4) lets the Board exceed 900 sq ft only for a carriage house or barn with preservation value, by special permit.
Max Size (Attached)Same cap — the smaller of 900 sq ft or half the house's gross floor area (§ 94-8.2.3(4); M.G.L. c. 40A § 1A). Medford sets no separate cap for an interior or attached unit. § 94-8.2.3(5) caps any increase in the house's gross floor area at 10 percent as an "external appearance" rule; a design standard that would not be applied to a single-family house is unreasonable under 760 CMR 71.03(3)(b)(1), so raise it in writing with the Building Commissioner if it is cited against an addition.
Max Size (JADU)Not a category in Massachusetts — no junior ADU exists in M.G.L. c. 40A, 760 CMR 71.00 or the Medford Zoning Ordinance. A unit carved out of the existing house is simply an ADU under the same 900 sq ft / half-GFA cap.
Max Height35 ft and 2½ stories for a dwelling in every residential district (Table B, row 1). Medford limits structures accessory to one- and two-family dwellings to 15 ft (§ 94-4.3.1(1)), but 760 CMR 71.03(3)(b)(2) bars any height or story standard stricter than the more permissive of the principal-dwelling and accessory-structure standards, which is 35 ft. The city has published no determination on this; confirm with the Building/Zoning Department at (781) 393-2509 before drawing a second story.
Max UnitsOne. § 94-8.2.3(3): "Not more than one accessory dwelling unit may be established on a lot," and 760 CMR 71.02 protects only one ADU per lot. A second would need a special permit under 760 CMR 71.03(5), and Medford's ordinance makes no provision for one. A protected-use ADU is not counted in density calculations (760 CMR 71.03(2)(d)).

Setback Requirements [1][2][3][4][5][6][7]

Medford requires a rear setback of about 3 ft for a detached ADU, and one off-street parking space is required. Owner-occupancy is not required — you can rent it out without living on the property.

Rear Setback3 ft for a detached ADU, or 1 ft with fire-resistance-rated wall assemblies (§ 94-4.3.2(3), accessory structures). A dwelling needs a 15 ft rear yard (Table B, row 1), but 760 CMR 71.03(3)(b)(2) gives the ADU the more permissive of the two. An accessory building may occupy up to 25 percent of the rear yard (§ 94-4.2.5(1)) and must sit at least 10 ft from the house and from any other accessory building (§ 94-4.1.2(3)(a)).
Side Setback3 ft from the side lot line for a detached ADU, or 1 ft with fire-resistance-rated walls (§ 94-4.3.2(3)) — more permissive than the 7½ ft side yard Table B requires of the house, so it governs under 760 CMR 71.03(3)(b)(2). § 94-4.3.2(1): in residential districts no accessory structure may stand in the required front or side yard, so a detached unit belongs in the rear yard. An attached ADU takes the house's own 7½ ft side yard.
Front Setback15 ft for the principal dwelling in all residential districts (Table B, row 1). A detached ADU may not be placed in the required front yard at all (§ 94-4.3.2(1)); an interior or attached unit uses the house's 15 ft front yard. Off-street parking may not be placed in the front yard in SF-1, SF-2 and GR (§ 94-6.1.4(3)).
Parking RequiredUsually none; at most one space. § 94-8.2.3(7) asks for "no more than one additional parking space, when necessary and feasible"; 760 CMR 71.03(2)(b) caps it at one and bars any space if any part of the lot is within 0.5 mile of a Transit Station, which 760 CMR 71.02 defines to include a Bus Station — any embarkation point for an MBTA bus. Wellington, Medford/Tufts, Ball Square and West Medford stations and the bus network cover most of the city; Table A's 2 spaces per unit binds the house only.
Owner OccupancyNot required. § 94-8.2.3(2) still demands an affidavit that one of the two units is owner-occupied, and § 94-8.2.3(8) expires the permit every five years without a fresh affidavit; the Building Department's ADU handout (September 7, 2022, still posted) repeats both. State law overrides them: M.G.L. c. 40A § 3 bars owner-occupancy requirements, 760 CMR 71.03(2)(a) lists them first among Prohibited Regulations, and 71.03(4) bars enforcing such a condition even if imposed before January 31, 2025.
Min Lot SizeNone for the ADU — 760 CMR 71.03(3)(b)(2) says a municipality "may not require a minimum Lot size for a Protected Use ADU." The district minimum for the house itself is 7,000 sq ft in SF-1 and 5,000 sq ft in every other district, with 35 ft frontage, 50 ft width, 55 ft depth and 40 percent maximum lot coverage (Table B, row 1). A nonconforming lot or house is not a bar: 760 CMR 71.03(3)(b)(9).

Permit Process & Fees [8][9][10][11][12][13][14][15]

An ADU permit in Medford goes through a standard permit review. Typical timeline: The Building Department's FAQ says the building official has 30 days to review and act on a building permit application and that most reviews finish sooner; new buildings go to the weekly Tuesday development meeting for multi-department sign-off. No ADU-specific timeline is published. Fees range from $15.00 per $1,000 of estimated construction cost plus a $35.00 application fee, a $100.00 plan review fee for 1-4 family dwellings and $125.00 for a certificate of occupancy (Schedule of Building Fees effective July 28, 2009; Code Appendix A, § 10-35) — about $3,885 on a $250,000 ADU.

Approval ProcessBuilding permit, filed online through the Citizenserve portal linked from the Building Department page (building, plumbing and gas, electrical and sheet-metal permits are all filed there; no work may start until the permit card is issued). No special permit and no hearing for one ADU: § 94-8.2.2 still reads "as of right in an existing principal dwelling or by special permit from the community development board (the SPGA) in an existing detached structure," but M.G.L. c. 40A § 3 forbids a special permit or other discretionary approval for a single ADU and 760 CMR 71.03(2)(e) bars requiring the unit to be attached or detached. Expect to file the § 94-8.2.3(1) plot plan (building, proposed unit, any septic system and parking; a mortgage inspection survey suffices). Zoning questions must go to the Building Commissioner in writing; Appendix A of the Code lists a $50 fee for a review or letter of legal zoning status. Building/Zoning Department, City Hall Room 115A, (781) 393-2509; Planning, Development & Sustainability, Room 308, (781) 393-2480, ocd@medford-ma.gov.
Review TimelineThe Building Department's FAQ says the building official has 30 days to review and act on a building permit application and that most reviews finish sooner; new buildings go to the weekly Tuesday development meeting for multi-department sign-off. No ADU-specific timeline is published.
Permit Fees$15.00 per $1,000 of estimated construction cost plus a $35.00 application fee, a $100.00 plan review fee for 1-4 family dwellings and $125.00 for a certificate of occupancy (Schedule of Building Fees effective July 28, 2009; Code Appendix A, § 10-35) — about $3,885 on a $250,000 ADU.
Impact FeesNone for a by-right ADU. 760 CMR 71.03(3)(b)(6) bars any impact fee or study not required of a single-family house in the same district. Medford's development linkage fees (§ 94-10.1.2) apply only to a "development impact project": nonresidential development of 10,000 sq ft or more, a residential structure of six or more units, a subdivision creating six or more units or lots, or a project of 5,000 sq ft or more that needs a density bonus, variance, special permit or map amendment. One ADU meets none of these.
Plan CheckStandard building plan review ($100.00 plan review fee, 1-4 family dwellings). Two Massachusetts items to settle early: Title 5 — if the lot is on septic, 310 CMR 15.000 applies through the Board of Health and the § 94-8.2.3(1) plot plan must show the system; and utilities — 760 CMR 71.03(3)(b)(3) says the city may not require a separate water, sewer or electric connection, though the utility or a state board still can. Work started without a permit is charged a quadruple fee (Appendix A, § 10-35(10)). Every ADU must be assigned an address to the MassGIS standard and reported to MassGIS and EOHLC (760 CMR 71.03(8)).
Pre-Approved PlansNone from the City of Medford — no plan gallery appears on the Building Department or Planning pages as of September 20, 2026. EOHLC's Accessory Dwelling Units page on mass.gov is the state's ADU resource hub; check it for plan and financing material before commissioning a custom set.

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Construction Costs [16][17][18]

Building an ADU in Medford typically costs $220,000-$400,000 ($275-$450 per sq ft); a garage conversion runs $100,000-$250,000.

See what this means for your lot — ask Medford ADU builders for a quote →

Average Build Cost$220,000-$400,000
Cost per Sq Ft$275-$450
Garage Conversion$100,000-$250,000
Prefab ADU (Installed)$250,000-$525,000

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Rental Income Potential [19][20]

A 2-bedroom ADU in Medford rents for around $3,000-$3,350/mo, an estimated 6-10% net annual yield (estimate: $220,000-$400,000 build, $2,500-$3,350/mo HUD-based rent, before financing).

Avg Rent (1 Bedroom)$2,500-$2,800/mo
Avg Rent (2 Bedroom)$3,000-$3,350/mo
Short-Term RentalNo — 30-day minimum rental term for the ADU or the house (§ 94-8.2.3(6)); state law lets a city restrict short-term rental of an ADU (M.G.L. c. 40A § 3; 760 CMR 71.03(3)(c)). Long-term letting of both units is allowed.
Est. Annual ROI6-10% net annual yield (estimate: $220,000-$400,000 build, $2,500-$3,350/mo HUD-based rent, before financing)

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Recent Law Changes

What's Changed Recently

  • The Affordable Homes Act, St. 2024, c. 150 §§ 7-8, effective February 2, 2025, rewrote the ADU definition at M.G.L. c. 40A § 1A and added to c. 40A § 3: "No zoning ordinance or by-law shall prohibit, unreasonably restrict or require a special permit or other discretionary zoning approval for the use of land or structures for a single accessory dwelling unit, or the rental thereof, in a single-family residential zoning district." Owner occupancy may not be required; no more than one parking space may be required, and none within half a mile of a commuter rail station, subway station, ferry terminal or bus station
  • EOHLC's regulation 760 CMR 71.00, Protected Use Accessory Dwelling Units, took effect January 31, 2025 (Mass. Register Issue 1540). It lists the Prohibited Regulations (owner occupancy, parking minimums, use and occupancy restrictions, unit caps, attached-or-detached requirements), defines Unreasonable Regulations (including dimensional standards stricter than the more permissive of the house's or an accessory structure's, minimum lot sizes, ADU-only impact fees and refusals for nonconformity) and, at 71.03(4), bars enforcing such conditions even where imposed before the effective date
  • Medford Zoning Ordinance § 94-8.2 has not been amended since Ord. No. 867 (March 22, 2022): the Municode edition (Supp. No. 18, codified through Ord. No. 889 of April 16, 2024, posted October 8, 2025) and the city's own consolidated Zoning Ordinance dated April 28, 2026 both carry the same text — Community Development Board special permit for a detached unit, owner-occupancy affidavit, five-year expiry. All three conditions are superseded by state law
  • The Building Department's handout "BUILDING DEPARTMENT — ACCESSORY DWELLING UNITS (ADU)," linked from its Applications, Forms, Permits and Regulations list and marked "Updated: September 7, 2022," still reprints the superseded conditions verbatim as of September 20, 2026. Treat it as a historical document and rely on M.G.L. c. 40A § 3 and 760 CMR 71.03
  • The City Council withdrew the residential and ADU zoning proposals on December 16, 2025 and referred them back to the Planning and Permitting Committee, after restarting the zoning project on December 3, 2025 with goals through May 2026. As of September 20, 2026 the city's Current Zoning Proposals page lists only the Boston Avenue Neighborhood Corridor District (latest item: September 15, 2026 City Council presentation); no ADU amendment has been adopted
  • What the overhaul has adopted is elsewhere: the Mystic Avenue Corridor District (December 17, 2024), the Salem Street Neighborhood Corridor District (voted March 11, 2025; map amendment December 2, 2025), Green Score (March 11, 2025), the Medford Square City Hall Overlay District (April 14, 2026) and the Medford Square District (April 28, 2026). None amends § 94-8.2, and in each new district Table A lists ADUs as N and detached single-family dwellings as N. The city's web summary of "ADUs by-right" in Urban Residential 1 and Neighborhood Residential 3 describes proposal subdistricts that were not adopted — § 94-9.7.2 creates only MS-1 to MS-4

Tips for Building an ADU in Medford

  • Print two things before you go to the counter: M.G.L. c. 40A § 3 and 760 CMR 71.03. Medford's ordinance and the Building Department's 2022 handout both still describe a special permit, an owner-occupancy affidavit and a five-year expiry, and none of the three survives the state law
  • Do the half-GFA arithmetic first. The cap is the smaller of 900 sq ft and half your house's gross floor area, so any house under 1,800 sq ft cuts you below 900 — and attics, crawl spaces, garages and enclosed porches do not count toward the house's GFA under 760 CMR 71.02
  • Use the accessory-structure setbacks, not the house's. Medford asks 15 ft at the rear and 7½ ft at the side for a dwelling but only 3 ft for an accessory structure (§ 94-4.3.2(3)), and 760 CMR 71.03(3)(b)(2) entitles you to whichever standard is more permissive. Leave the 10 ft between the house and the cottage that § 94-4.1.2(3)(a) requires, and keep the unit out of the front and side yards
  • Check your distance to a bus stop, not just to Wellington or Medford/Tufts. 760 CMR 71.02 defines a Bus Station as any point of embarkation for a Transit Authority bus, and if any part of your lot is within half a mile of one, no parking space may be required at all
  • You are not confined to SF-1 and SF-2. A detached single-family dwelling is a permitted use in GR, APT-1 and APT-2 as well (Table A), and 760 CMR 71.02 makes every one of those a "Single-family Residential Zoning District" for ADU purposes. Lots rezoned into the Mystic Avenue, Salem Street or Medford Square districts are the exception — single-family is not a permitted use there
  • Fee math: on a $250,000 detached unit expect roughly $3,750 (at $15 per $1,000) + $35 application + $100 plan review = $3,885, plus separate plumbing and gas, electrical and sheet-metal permits on their own schedules, and $125 for the certificate of occupancy. Start work without a permit and the fee is quadrupled
  • Ask in writing. The Building Department page says any inquiry about the legal zoning status of a building or a future use must be submitted in writing to the Building Commissioner; Appendix A prices a review or letter of legal zoning status at $50. A written answer on the special-permit and owner-occupancy questions is worth having before you spend on drawings
  • Do not accept a refusal because your lot or house is nonconforming — 760 CMR 71.03(3)(b)(9) forbids exactly that, and the definition of Principal Dwelling at 760 CMR 71.02 expressly covers a structure that does not conform to setbacks, bulk or height
  • Plan for tenants on 30-day-plus leases. The short-term rental floor at § 94-8.2.3(6) is one of the few parts of Medford's ADU section that state law leaves standing, and Medford separately regulates short-term rentals at § 94-8.4
  • Rent check: HUD's FY2027 Small Area Fair Market Rents for ZIP 02155 (Medford) are $2,700 for a studio, $2,790 for a one-bedroom and $3,330 for a two-bedroom, against a Boston-Cambridge-Quincy metro FMR of $2,518 / $3,008 — a 700-900 sq ft ADU sits in the one-bedroom band
  • Cost basis: build and per-sq-ft figures are statewide 2026 industry guides (Dwelly, March 2026: $275-$450 per sq ft, 800 sq ft $220,000-$360,000, 1,000 sq ft $275,000-$450,000; Horizon ADU, July 2026: detached cottage $250,000-$360,000, basement or garage conversion $100,000-$250,000; ADU Wizard, 2026: prefab installed 650-900 sq ft $250,000-$525,000 in Greater Boston). No Medford-specific guide exists; get three local bids

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Sources & References

All data on this page is sourced from official government records and verified market data. View our full methodology.

  1. Medford Zoning Ordinance § 94-8.2, Accessory dwelling units (ADU) — Code of Ordinances Ch. 94 (Ord. No. 867, 3-22-2022; no later history note), Municode Supp. No. 18, codified through Ord. No. 889 (4-16-2024), posted 10-8-2025 Municipal Code — Accessed 2026-09-20
  2. Medford Zoning Ordinance, Chapter 94, consolidated text dated April 28, 2026 (City of Medford Adopted Zoning Proposals page) — § 94-8.2, § 94-3.3.5, § 94-4.1.2(3), § 94-4.2.5, § 94-4.3, § 94-6.1.4(3), § 94-9.7, § 94-10.1.2, Table A (June 11, 2024), Table B (March 15, 2022) Municipal Code — Accessed 2026-09-20
  3. Medford Square District Zoning Amendment, adopted April 28, 2026 (inserts § 94-9.7; Table A rows for MS-1 to MS-4: ADUs N, detached one-unit dwelling N) Municipal Code — Accessed 2026-09-20
  4. Medford Zoning Ordinance § 94-2.1, § 94-4.1 to § 94-4.3, Table A and Table B, Appendix A fee schedule — Municode Code of Ordinances (Supp. No. 18) Municipal Code — Accessed 2026-09-20
  5. 760 CMR 71.02, Definitions — Protected Use Accessory Dwelling Units (ADU, Gross Floor Area, Single-family Residential Zoning District, Transit Station, Bus Station), eff. 1/31/2025 state_statute — Accessed 2026-09-20
  6. 760 CMR 71.03, Regulation of Protected Use ADUs in Single-family Residential Zoning Districts — Prohibited and Unreasonable Regulations, eff. 1/31/2025 (Mass. Register 1540) state_statute — Accessed 2026-09-20
  7. ADU Law — Acts of 2024, Chapter 150, Sections 7 and 8 (amendments to M.G.L. c. 40A §§ 1A and 3), EOHLC state_statute — Accessed 2026-09-01
  8. City of Medford Building Department — Accessory Dwelling Units (ADU) handout, "Updated: September 7, 2022" (still published; reprints superseded § 94-8.2 conditions) Planning Department — Accessed 2026-09-20
  9. City of Medford Schedule of Building Fees, effective July 28, 2009 (Building fees PDF linked from the Building Department page; same figures as Code Appendix A, § 10-35) Planning Department — Accessed 2026-09-20
  10. Building Department — City of Medford (Citizenserve online permitting, ADU handout link, 30-day review FAQ, written zoning inquiries, fee schedules, contacts) Planning Department — Accessed 2026-09-20
  11. Code of Ordinances Appendix A — Fee Schedule, Chapter 10 Article II Schedule of Building Fees (§ 10-35): $15 per $1,000, $35 application, $125 C of O, $100 plan review, quadruple fee Municipal Code — Accessed 2026-09-20
  12. Zoning — City of Medford Office of Planning, Development & Sustainability (2025-2026 updates: residential and ADU proposals withdrawn December 16, 2025) Planning Department — Accessed 2026-09-20
  13. Current Zoning Proposals — City of Medford (Boston Avenue Neighborhood Corridor District only, latest item September 15, 2026) Planning Department — Accessed 2026-09-20
  14. Adopted Zoning Proposals — City of Medford (Phase 1 June 2024, Mystic Avenue Corridor, Salem Street Corridor, Green Score, Medford Square City Hall Overlay 4/14/26, Medford Square District 4/28/26; consolidated ordinance PDF) Planning Department — Accessed 2026-09-20
  15. Accessory Dwelling Units — EOHLC (state ADU resource page) Government Data — Accessed 2026-09-01
  16. Dwelly, How Much Does an ADU Cost in Massachusetts in 2026? (Mar 7, 2026) industry — Accessed 2026-09-20
  17. Horizon ADU, How Much Does a 900 Sq Ft ADU Cost in Massachusetts? (Jul 24, 2026) industry — Accessed 2026-09-20
  18. ADU Wizard, How Much Does an ADU Cost in Massachusetts in 2026? industry — Accessed 2026-09-20
  19. HUD FY2027 Small Area Fair Market Rent Schedule, Boston-Cambridge-Quincy, MA-NH HUD Metro FMR Area — ZIP 02155 (Medford) Government Data — Accessed 2026-09-20
  20. HUD FY2027 Fair Market Rents, Boston-Cambridge-Quincy, MA-NH HMFA Government Data — Accessed 2026-09-20
  21. Planning, Development & Sustainability — City of Medford (contacts: (781) 393-2480, ocd@medford-ma.gov) Planning Department — Accessed 2026-09-20
  22. U.S. Census Bureau — 2020 Decennial Census, Medford city, Massachusetts (59,659) Government Data — Accessed 2026-09-01

Frequently Asked Questions

Can I build an ADU in Medford?

Yes. ADUs are allowed in SF-1, SF-2, GR, APT-1 and APT-2 — every district where a detached single-family dwelling is a permitted use (Table A, row A.1). 760 CMR 71.02 defines a "Single-family Residential Zoning District" as any district where single-family dwellings are permitted or allowable, so the protection is not confined to SF-1 and SF-2. None arises in ROS, APT-3, C-1, C-2, I, O, O-2, MUZ or the new Mystic Avenue, Salem Street and Medford Square districts (single-family is N there). Confirm at (781) 393-2480. in Medford. The maximum size for a detached ADU is The smaller of 900 sq ft or half the principal dwelling's gross floor area. Medford § 94-8.2.3(4) and M.G.L. c. 40A § 1A / 760 CMR 71.02 agree on the number. Under 760 CMR 71.02, GFA counts every story of compliant ceiling height including basements and lofts but excludes crawl spaces, garages, attics and enclosed porches — so a 1,400 sq ft house gets a 700 sq ft unit. § 94-8.2.3(4) lets the Board exceed 900 sq ft only for a carriage house or barn with preservation value, by special permit.. Owner-occupancy is not required, so you can rent out the ADU.

How much does an ADU cost in Medford?

ADU construction in Medford typically costs $220,000-$400,000. Garage conversions run $100,000-$250,000, and prefab ADUs cost $250,000-$525,000.

How much can I rent an ADU for in Medford?

Average ADU rents in Medford are $2,500-$2,800/mo for a 1-bedroom and $3,000-$3,350/mo for a 2-bedroom unit.

Do I need parking for an ADU in Medford?

Usually none; at most one space. § 94-8.2.3(7) asks for "no more than one additional parking space, when necessary and feasible"; 760 CMR 71.03(2)(b) caps it at one and bars any space if any part of the lot is within 0.5 mile of a Transit Station, which 760 CMR 71.02 defines to include a Bus Station — any embarkation point for an MBTA bus. Wellington, Medford/Tufts, Ball Square and West Medford stations and the bus network cover most of the city; Table A's 2 spaces per unit binds the house only.. Check with Medford planning department for the latest Massachusetts ADU parking rules, as many states have relaxed requirements in recent years.

How long does it take to get an ADU permit in Medford?

The permit review timeline in Medford is The Building Department's FAQ says the building official has 30 days to review and act on a building permit application and that most reviews finish sooner; new buildings go to the weekly Tuesday development meeting for multi-department sign-off. No ADU-specific timeline is published.. Fees range from $15.00 per $1,000 of estimated construction cost plus a $35.00 application fee, a $100.00 plan review fee for 1-4 family dwellings and $125.00 for a certificate of occupancy (Schedule of Building Fees effective July 28, 2009; Code Appendix A, § 10-35) — about $3,885 on a $250,000 ADU.

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Medford ADU FAQ

Answers to every common question about building an ADU in Medford — costs, rules, permits, rental income.

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Medford ADU Costs

Detailed cost breakdown: construction $220,000-$400,000, garage conversion $100,000-$250,000, plus ROI analysis.

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Garage Conversion ADU Guide

Complete guide to costs ($80K-$180K), impact fee savings, and permits for garage-to-ADU conversions.

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ADU vs Mother-in-Law Suite

Legal differences that affect what you can build, how you can use it, and rental rights.

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About this information: This page is an informational summary of publicly available regulations - it is not legal, financial, or professional advice, and it is not a substitute for confirming requirements with your local planning department. Rules change frequently; always verify current requirements before designing, budgeting, or building. Last verified: 2026-09-20. Contractors we introduce are independent businesses - verify license and insurance directly before hiring. Spotted an error? Tell us - we verify against primary sources and correct quickly.

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