You can build an ADU in Medford by right, and almost everything that makes that true comes from state law rather than from Medford's own by-law. The Affordable Homes Act (St. 2024, c. 150, §§ 7-8), codified at M.G.L. c. 40A §§ 1A and 3 and effective February 2, 2025, made a single accessory dwelling unit a protected use in any single-family residential zoning district — no special permit, no owner occupancy, no hearing. Medford's local section, § 94-8.2 of the Zoning Ordinance, has not been rewritten since Ordinance No. 867 of March 22, 2022, and still says the opposite on three points: it requires a special permit from the Community Development Board for a detached unit, it requires an affidavit that one of the two units be owner-occupied, and it makes the permit expire after five years unless you re-file that affidavit. All three are superseded. Worse, the Building Department's own ADU handout — the one linked from its permits page, marked "Updated: September 7, 2022" — reprints the obsolete rules word for word, so a homeowner reading the city's own guidance in 2026 gets told the wrong thing. Print M.G.L. c. 40A § 3 and 760 CMR 71.03 and take them to the counter. Two other things worth knowing: the state protection reaches SF-1, SF-2, GR, APT-1 and APT-2, not just the two single-family districts, and because 760 CMR 71.02 defines a "Bus Station" as any point of embarkation for a Transit Authority bus, very little of Medford is more than half a mile from one — which under 760 CMR 71.03(2)(b)(2) means no parking space may be required at all.
Zoning & Size Requirements [1][2][3][4][5]
Yes — Medford allows ADUs. A detached ADU can typically be up to 900 sq ft under current Massachusetts and Medford zoning rules.
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| Allowed Zones | SF-1, SF-2, GR, APT-1 and APT-2 — every Medford district in which a detached single-family dwelling is a permitted use (Medford Zoning Ordinance Table A, row A.1; districts listed at § 94-2.1). That is wider than most homeowners assume, because 760 CMR 71.02 defines a "Single-family Residential Zoning District" as "[a]ny Zoning District where Single-family Residential Dwellings are a permitted or an allowable use, including any Zoning District where Single-family Residential Dwellings are allowed as-of-right or by Special Permit" — so the state's by-right ADU protection is not confined to SF-1 and SF-2. Detached single-family dwellings are not permitted in ROS, APT-3, C-1, C-2, I, O, O-2 or MUZ, so no protected-use ADU arises there. Confirm your parcel's district with Medford Planning, Development & Sustainability at (781) 393-2480 or the Building/Zoning Department at (781) 393-2509 |
| Max Size (Detached) | The smaller of 900 sq ft or half the gross floor area of the principal dwelling. On this point Medford and the Commonwealth agree: "The accessory dwelling unit shall not be larger in floor area than one-half the floor area of the principal dwelling, or 900 square feet, whichever is smaller" (Medford Zoning Ordinance § 94-8.2.3(4)), and M.G.L. c. 40A § 1A defines an ADU as one that "is not larger in gross floor area than 1/2 the gross floor area of the principal dwelling or 900 square feet, whichever is smaller." Note which way that cuts: if your house is under 1,800 sq ft of gross floor area, the half-GFA rule binds long before the 900 does — a 1,400 sq ft house buys a 700 sq ft ADU. Gross floor area is measured under 760 CMR 71.02 as the sum of all stories of compliant ceiling height including basements and lofts, "but excluding crawl spaces, garage parking areas, attics, enclosed porches and similar spaces," so an unfinished attic or an attached garage does not enlarge your allowance. Medford's own text lets the Community Development Board make an exception "in the event that the detached accessory structure has some preservation value, as with a carriage house or a barn" — that is a discretionary route above 900 sq ft, not a right |
| Max Size (Attached) | The same limit — the smaller of 900 sq ft or half the principal dwelling's gross floor area (Medford Zoning Ordinance § 94-8.2.3(4); M.G.L. c. 40A § 1A). Medford applies no separate cap to an interior conversion. Its § 94-8.2.3(5) does cap any increase in gross floor area at ten percent as part of an "external appearance" rule, which in practice would bar most attached additions; see the note under max_height on why that provision is doubtful as applied to a protected-use ADU |
| Max Size (JADU) | Not a category in Massachusetts — there is no junior ADU designation in M.G.L. c. 40A, in 760 CMR 71.00 or in the Medford Zoning Ordinance. An ADU carved out of the existing house is simply an ADU, subject to the same 900 sq ft / half-GFA cap |
| Max Height | 35 feet and 2½ stories for the principal dwelling in every Medford residential district (Medford Zoning Ordinance Table B, row 1). Medford separately limits structures accessory to one- and two-family dwellings to 15 feet (§ 94-4.3.1(1)), which read literally would squeeze a detached ADU into a single storey. It should not apply: 760 CMR 71.03(3)(b)(2) makes unreasonable any dimensional standard — expressly including "bulk and height, and number of stories" — "that are more restrictive than is required for the Principal Dwelling, or a Single-family Residential Dwelling or accessory structure in the Zoning District in which the Protected Use ADU is located, whichever results in more permissive regulation." The more permissive of the two is 35 feet. Take the regulation with you and confirm with the Building/Zoning Department at (781) 393-2509 before you draw a second storey |
| Max Units | 1. Medford allows one: "Not more than one accessory dwelling unit may be established on a lot" (Medford Zoning Ordinance § 94-8.2.3(3)), and state law protects exactly one — M.G.L. c. 40A § 3 speaks of "a single accessory dwelling unit," and 760 CMR 71.02 provides that "only one ADU on a lot may qualify as a Protected Use ADU." A second would need a special permit under M.G.L. c. 40A § 3 and 760 CMR 71.03(5), but Medford's by-law makes no provision for one, so treat one as the practical ceiling until the ordinance is rewritten. Protected-use ADUs "shall not be counted in any density calculations" (760 CMR 71.03(2)(d)) |
Setback Requirements [1][2][3][4][5]
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 Setback | 3 feet for a detached ADU, or 1 foot if it is built with fire-resistance-rated wall assemblies. Medford requires a 15-foot rear yard for a detached single-family dwelling (Table B, row 1) but only that "[a]ny accessory structures must be set back a minimum of three feet from rear and side lot lines, or a one foot separation from lot lines if constructed of fire-resistance wall assemblies, as defined by the State Building Code" (§ 94-4.3.2(3)). Under 760 CMR 71.03(3)(b)(2) the more permissive of the two standards controls, which is the 3-foot accessory-structure rule. One local constraint that does bite and is not a setback: a building accessory to a single- or two-family detached dwelling "shall not be less than ten feet from that detached dwelling unless part of and attached to that dwelling" (§ 94-4.1.2(3)(a)), so plan for a 10-foot gap between the house and the cottage |
| Side Setback | 3 feet from the side lot line for a detached ADU (Medford Zoning Ordinance § 94-4.3.2(3)), or 1 foot with fire-resistance-rated wall assemblies — again more permissive than the 7½-foot side yard Table B requires of the house, and so the standard that governs under 760 CMR 71.03(3)(b)(2). Read it together with § 94-4.3.2(1): "In residential districts, no accessory structure shall be located within the required front or side yard or any court but may be built in the rear yard." The practical result is that a detached ADU belongs in the rear yard, and inside that rear yard it needs 3 feet of clearance to the side and rear lines |
| Front Setback | 15 feet for the principal dwelling in all residential districts (Medford Zoning Ordinance Table B, row 1), and a detached ADU may not sit in the required front yard at all — § 94-4.3.2(1) bars accessory structures from the required front or side yard. An ADU inside or attached to the house takes the house's own 15-foot front yard. Medford also bars off-street parking within the front yard in the SF-1, SF-2 and GR districts (§ 94-6.1.4(3)) |
| Parking Required | Probably none, and never more than one space. Medford's by-law asks for "no more than one (1) additional parking space, when necessary and feasible" (§ 94-8.2.3(7)). State law caps that and, over most of Medford, cancels it: a municipality may not require "[a]ny additional on-street or off-street parking space for a Protected Use ADU if any portion of its Lot is located within a 0.5 mile radius of a Transit Station" (760 CMR 71.03(2)(b)(2)), and may not require more than one space outside that radius. "Transit Station" is defined at 760 CMR 71.02 to include a "Bus Station," which is in turn "[a] location serving as a point of embarkation for any bus operated by a Transit Authority" — on its face, any MBTA bus stop. Medford also has the Orange Line at Wellington, the Green Line Extension at Medford/Tufts and Ball Square, and Lowell Line commuter rail at West Medford. Between them there is very little of the city that sits more than half a mile from something that qualifies. Confirm how the Building Department is applying the half-mile radius at (781) 393-2509 before you give up a parking space, and note that Medford's general requirement of 2 spaces per dwelling unit (parking code A, § 94-6.1.3) does not reach a protected-use ADU |
| Owner Occupancy | Not required — and this is the single provision where Medford's published rules are most clearly wrong. Section 94-8.2.3(2) still says "[a]n affidavit shall be provided stating that one of the two dwelling units shall be occupied by the owner of the property," and § 94-8.2.3(8) makes the permit expire after five years unless the owner re-files that affidavit. Both are superseded. M.G.L. c. 40A § 3 provides that the use of land or structures for an ADU "shall not require owner occupancy of either the accessory dwelling unit or the principal dwelling," and 760 CMR 71.03(2)(a) lists an owner-occupancy requirement first among the Prohibited Regulations. 760 CMR 71.03(4) goes further and bars a municipality from enforcing such a condition even where it was imposed before January 31, 2025. The related ban on holding the ADU "in separate ownership from the principal structure/dwelling unit" in the same subsection travels with the owner-occupancy scheme — ask the Building Commissioner in writing how the city is applying it |
| Min Lot Size | None may be imposed on the ADU itself: 760 CMR 71.03(3)(b)(2) provides that "a Municipality may not require a minimum Lot size for a Protected Use ADU." The underlying district minimums for the lot are 7,000 sq ft for a detached single-family dwelling in SF-1 and 5,000 sq ft in all other districts, with 35 feet of frontage, 50 feet of width and 55 feet of depth (Medford Zoning Ordinance Table B, row 1). Maximum lot coverage is 40 percent for a detached single-family dwelling. And if your lot or your house is already nonconforming, that is not a bar: 760 CMR 71.03(3)(b)(9) says a municipality "may not prohibit the development of a Protected Use ADU in an existing structure or Principal Dwelling, or Lot due to nonconformance" |
Permit Process & Fees [6][7][8][9][10]
An ADU permit in Medford goes through a standard permit review. Confirm with the Medford Building Department at (781) 393-2509 — the city publishes no ADU-specific review timeline. What you can count on is that there is no hearing to wait for: because one ADU is a protected use under M.G.L. c. 40A § 3, there is no Community Development Board agenda, no abutter notice and no 20-day appeal period on a special permit, so the clock is ordinary building-permit review rather than a discretionary land-use calendar. Permit fees: From the city's posted Schedule of Building Fees (effective July 28, 2009 and still the version linked from the Building Department page): $15.00 per $1,000.00 of estimated construction cost, plus a $35.00 application fee; a Plan Review Fee for 1-4 family dwelling units of $100.00; and a certificate of occupancy for an existing residential building at $125.00. On a $250,000 ADU that is roughly $3,750 + $35 + $100, about $3,885, before separate plumbing and gas, electrical and sheet metal/mechanical permits, which are billed on their own schedules. Note the sting in the tail: work started without a building permit is charged a QUADRUPLE FEE.
| Approval Process | A building permit, filed online through the city's Citizenserve portal from the Building Department's permits page; three sets of plans are required by the state building code. No special permit and no public hearing are needed for one ADU, whatever the local text says. Medford's § 94-8.2.2 still reads: "Accessory dwelling units may be allowed as of right in an existing principal dwelling or by special permit from the community development board (the SPGA) in an existing detached structure on the same lot" — but M.G.L. c. 40A § 3 forbids any "special permit or other discretionary zoning approval" for a single ADU in a single-family residential zoning district, and 760 CMR 71.03(2)(e) separately bars a municipality from requiring that an ADU "be attached to or detached from the Principal Dwelling." Note also that Medford's text contemplates only conversions of existing buildings; new detached construction is not addressed at all, which is not a lawful basis for refusal. You will still need to file the § 94-8.2.3(1) plot plan showing the building on the lot, the proposed unit, any septic system and parking — a mortgage inspection survey suffices. Building/Zoning Department, City Hall Room 115A, (781) 393-2509; Planning, Development & Sustainability, Room 308, (781) 393-2480, ocd@medford-ma.gov |
| Review Timeline | Confirm with the Medford Building Department at (781) 393-2509 — the city publishes no ADU-specific review timeline. What you can count on is that there is no hearing to wait for: because one ADU is a protected use under M.G.L. c. 40A § 3, there is no Community Development Board agenda, no abutter notice and no 20-day appeal period on a special permit, so the clock is ordinary building-permit review rather than a discretionary land-use calendar |
| Permit Fees | From the city's posted Schedule of Building Fees (effective July 28, 2009 and still the version linked from the Building Department page): $15.00 per $1,000.00 of estimated construction cost, plus a $35.00 application fee; a Plan Review Fee for 1-4 family dwelling units of $100.00; and a certificate of occupancy for an existing residential building at $125.00. On a $250,000 ADU that is roughly $3,750 + $35 + $100, about $3,885, before separate plumbing and gas, electrical and sheet metal/mechanical permits, which are billed on their own schedules. Note the sting in the tail: work started without a building permit is charged a QUADRUPLE FEE |
| Impact Fees | None for a by-right ADU. Massachusetts municipalities have no general ADU impact fee power, and 760 CMR 71.03(3)(b)(6) makes unreasonable "[a]ny requirement for any impact analysis, study, report, or impact fee that is not required for the development of a Single-family Residential Dwelling" in the same district. Medford's own development linkage fees at § 94-10.1 are triggered only by a residential development of six units or more, a subdivision creating six or more units or lots, a nonresidential project of 10,000 sq ft or more, or a project of 5,000 sq ft or more that needs a density bonus, variance, special permit or map amendment — an ADU built by right meets none of those thresholds |
| Plan Check | Standard building plan review; the state building code requires three sets of plans, and Medford charges a $100.00 Plan Review Fee for 1-4 family dwelling units. Two Massachusetts-specific items to check early. First, Title 5: if the property is on a septic system rather than sewer, 310 CMR 15.000 applies and is expressly preserved by M.G.L. c. 40A § 3, and MassDEP issued Title 5 guidance for ADUs updated September 11, 2025 — the local Board of Health, not the Building Department, is the authority. Second, utilities: 760 CMR 71.03(3)(b)(3) says a municipality "may not require a separate utility connection, such as water, sewer, electric," though the utility itself, a state or regional board, or a court still can. Every ADU must also be assigned an address to the MassGIS standard and reported to MassGIS and EOHLC (760 CMR 71.03(8)) |
| Pre-Approved Plans | None from the City of Medford — no city plan gallery appears on the Building Department or Planning pages as of September 1, 2026. The Commonwealth fills the gap: EOHLC's Accessory Dwelling Units page hosts a free, searchable library of downloadable ADU designs alongside financing and technical-assistance programmes. Start there before you commission a custom set |
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Construction Costs [11]
Building an ADU in Medford typically costs $230,000-$400,000 ($300-$500 per sq ft); a garage conversion runs $115,000-$230,000.
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| Average Build Cost | $230,000-$400,000 |
| Cost per Sq Ft | $300-$500 |
| Garage Conversion | $115,000-$230,000 |
| Prefab ADU (Installed) | $165,000-$330,000 |
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Rental Income Potential [12][13]
A 2-bedroom ADU in Medford rents for around $2,600-$3,200/mo, an estimated 5-8% annual return.
| Avg Rent (1 Bedroom) | $2,100-$2,600/mo |
| Avg Rent (2 Bedroom) | $2,600-$3,200/mo |
| Short-Term Rental | No — 30-day minimum. "Where the accessory dwelling unit or the principal dwelling is occupied as a rental unit, the minimum occupancy or rental term shall be 30 days" (Medford Zoning Ordinance § 94-8.2.3(6)). This one survives the state law rather than falling to it: M.G.L. c. 40A § 3 expressly allows an ADU to "be subject to restrictions and prohibitions on short-term rental, as defined in section 1 of chapter 64G," and 760 CMR 71.03(3)(c) repeats the point. Long-term letting is unrestricted and, with owner occupancy gone, you may rent both units |
| Est. Annual ROI | 5-8% annual return |
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Recent Law Changes
What's Changed Recently
- The Affordable Homes Act, St. 2024, c. 150 §§ 7-8, signed August 6, 2024 and effective February 2, 2025, rewrote the ADU definition at M.G.L. c. 40A § 1A and added a paragraph to M.G.L. 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; not 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 promulgated 760 CMR 71.00, Protected Use Accessory Dwelling Units, published in the Massachusetts Register (Issue 1540) and effective January 31, 2025. It defines the Prohibited Regulations (owner occupancy, minimum parking, use and occupancy restrictions, unit caps and density counting, any requirement that the unit be attached or detached) and the test for an Unreasonable Regulation, and at 760 CMR 71.03(4) bars a municipality from enforcing such conditions even where they were imposed before the regulation took effect
- Medford Zoning Ordinance § 94-8.2 has not been amended since Ordinance No. 867, adopted March 22, 2022, which repealed the old Chapter 94 and enacted the present one. It still requires a Community Development Board special permit for a detached unit, an owner-occupancy affidavit, and a five-year permit expiry renewable only on a fresh owner-occupancy affidavit — all superseded
- The Medford Building Department's own handout, "BUILDING DEPARTMENT — ACCESSORY DWELLING UNITS (ADU)," linked from its Applications, Forms, Permits and Regulations list and marked "Updated: September 7, 2022," reprints those obsolete conditions verbatim, including the owner-occupancy affidavit and the five-year expiry. As of September 1, 2026 it had not been revised for the state law. Treat it as a historical document
- Medford's Planning and Permitting Committee reviewed a draft ADU ordinance to conform § 94-8.2 to the state law and the EOHLC model zoning through 2025, but the City Council withdrew the residential and ADU zoning proposals in December 2025 and referred them back to committee. The zoning project restarted on a plan agreed at the December 2, 2025 Council meeting; as of September 1, 2026 the city's Current Zoning Proposals page lists only the Tufts/Boston Ave proposal, and no amended ADU ordinance has been adopted
- What Medford has adopted in the overhaul so far is elsewhere: the Medford Square zoning, the Salem Street Corridor District, Green Score and the Mystic Avenue Corridor District. None of them changes § 94-8.2
- The Municode version of the Medford Code of Ordinances relied on for this entry is current through October 8, 2025
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 anything under an 1,800 sq ft house 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 feet at the rear and 7½ at the side for a dwelling but only 3 feet for an accessory structure, and 760 CMR 71.03(3)(b)(2) entitles you to whichever standard is more permissive. Leave the 10 feet between the house and the cottage that § 94-4.1.2(3)(a) requires
- 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, and 760 CMR 71.02 makes every one of those a "Single-family Residential Zoning District" for ADU purposes
- Do not accept a refusal based on your lot or house being 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 ban at § 94-8.2.3(6) is one of the few parts of Medford's ADU section that state law leaves standing
- If the plan reviewer raises § 94-8.2.3(5) — no more than a ten percent increase in gross floor area and no additional entrance facing the principal street — note that a separate entrance is part of the statutory definition of an ADU at M.G.L. c. 40A § 1A, and that a design standard which would not be applied to a single-family dwelling, or which unreasonably increases the cost of building an ADU, is unreasonable under 760 CMR 71.03(3)(b)(1)
ADU Builders in Medford
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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.
- Medford Zoning Ordinance § 94-8.2, Accessory dwelling units (ADU) — Code of Ordinances Ch. 94 (Ord. No. 867, adopted 3-22-2022), current through Oct. 8, 2025 Municipal Code — Accessed 2026-09-01
- Medford Zoning Ordinance § 94-4.1 to § 94-4.3 and Table B — dimensional requirements; accessory structure height and location Municipal Code — Accessed 2026-09-01
- Medford Zoning Ordinance § 94-2.1 and Table A — zoning districts; table of use and parking regulations Municipal Code — Accessed 2026-09-01
- ADU Law — Acts of 2024, Chapter 150, Sections 7 and 8 (full text of the amendments to M.G.L. c. 40A §§ 1A and 3), EOHLC state_statute — Accessed 2026-09-01
- 760 CMR 71.00: Protected Use Accessory Dwelling Units — EOHLC, adopted Mass. Register Issue 1540, eff. 1/31/2025 state_statute — Accessed 2026-09-01
- City of Medford Building Department — Accessory Dwelling Units (ADU) handout, "Updated: September 7, 2022" (still published; reprints superseded rules) Planning Department — Accessed 2026-09-01
- City of Medford Schedule of Building Fees, effective July 28, 2009 (as posted on the Building Department page) Planning Department — Accessed 2026-09-01
- Building Department — City of Medford (online permitting, contacts, fee schedules) Planning Department — Accessed 2026-09-01
- Accessory Dwelling Units — EOHLC (FAQ, free ADU design library, Title 5 and MassGIS guidance) Government Data — Accessed 2026-09-01
- Zoning / Current and Adopted Zoning Proposals — City of Medford Office of Planning, Development & Sustainability Planning Department — Accessed 2026-09-01
- Angi — ADU Construction Cost Data Market Data — Accessed 2026-09-01
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-09-01
- HUD Fair Market Rents Government Data — Accessed 2026-09-01
- Planning, Development & Sustainability — City of Medford (contacts: (781) 393-2480, ocd@medford-ma.gov) Planning Department — Accessed 2026-09-01
- 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 Medford district in which a detached single-family dwelling is a permitted use (Medford Zoning Ordinance Table A, row A.1; districts listed at § 94-2.1). That is wider than most homeowners assume, because 760 CMR 71.02 defines a "Single-family Residential Zoning District" as "[a]ny Zoning District where Single-family Residential Dwellings are a permitted or an allowable use, including any Zoning District where Single-family Residential Dwellings are allowed as-of-right or by Special Permit" — so the state's by-right ADU protection is not confined to SF-1 and SF-2. Detached single-family dwellings are not permitted in ROS, APT-3, C-1, C-2, I, O, O-2 or MUZ, so no protected-use ADU arises there. Confirm your parcel's district with Medford Planning, Development & Sustainability at (781) 393-2480 or the Building/Zoning Department at (781) 393-2509 in Medford. The maximum size for a detached ADU is The smaller of 900 sq ft or half the gross floor area of the principal dwelling. On this point Medford and the Commonwealth agree: "The accessory dwelling unit shall not be larger in floor area than one-half the floor area of the principal dwelling, or 900 square feet, whichever is smaller" (Medford Zoning Ordinance § 94-8.2.3(4)), and M.G.L. c. 40A § 1A defines an ADU as one that "is not larger in gross floor area than 1/2 the gross floor area of the principal dwelling or 900 square feet, whichever is smaller." Note which way that cuts: if your house is under 1,800 sq ft of gross floor area, the half-GFA rule binds long before the 900 does — a 1,400 sq ft house buys a 700 sq ft ADU. Gross floor area is measured under 760 CMR 71.02 as the sum of all stories of compliant ceiling height including basements and lofts, "but excluding crawl spaces, garage parking areas, attics, enclosed porches and similar spaces," so an unfinished attic or an attached garage does not enlarge your allowance. Medford's own text lets the Community Development Board make an exception "in the event that the detached accessory structure has some preservation value, as with a carriage house or a barn" — that is a discretionary route above 900 sq ft, not a right. 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 $230,000-$400,000. Garage conversions run $115,000-$230,000, and prefab ADUs cost $165,000-$330,000.
How much can I rent an ADU for in Medford?
Average ADU rents in Medford are $2,100-$2,600/mo for a 1-bedroom and $2,600-$3,200/mo for a 2-bedroom unit.
Do I need parking for an ADU in Medford?
Probably none, and never more than one space. Medford's by-law asks for "no more than one (1) additional parking space, when necessary and feasible" (§ 94-8.2.3(7)). State law caps that and, over most of Medford, cancels it: a municipality may not require "[a]ny additional on-street or off-street parking space for a Protected Use ADU if any portion of its Lot is located within a 0.5 mile radius of a Transit Station" (760 CMR 71.03(2)(b)(2)), and may not require more than one space outside that radius. "Transit Station" is defined at 760 CMR 71.02 to include a "Bus Station," which is in turn "[a] location serving as a point of embarkation for any bus operated by a Transit Authority" — on its face, any MBTA bus stop. Medford also has the Orange Line at Wellington, the Green Line Extension at Medford/Tufts and Ball Square, and Lowell Line commuter rail at West Medford. Between them there is very little of the city that sits more than half a mile from something that qualifies. Confirm how the Building Department is applying the half-mile radius at (781) 393-2509 before you give up a parking space, and note that Medford's general requirement of 2 spaces per dwelling unit (parking code A, § 94-6.1.3) does not reach a protected-use ADU. 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?
Medford does not publish a standard ADU review timeline — confirm with the Medford Building Department at (781) 393-2509 — the city publishes no ADU-specific review timeline. What you can count on is that there is no hearing to wait for: because one ADU is a protected use under M.G.L. c. 40A § 3, there is no Community Development Board agenda, no abutter notice and no 20-day appeal period on a special permit, so the clock is ordinary building-permit review rather than a discretionary land-use calendar. Permit fees: From the city's posted Schedule of Building Fees (effective July 28, 2009 and still the version linked from the Building Department page): $15.00 per $1,000.00 of estimated construction cost, plus a $35.00 application fee; a Plan Review Fee for 1-4 family dwelling units of $100.00; and a certificate of occupancy for an existing residential building at $125.00. On a $250,000 ADU that is roughly $3,750 + $35 + $100, about $3,885, before separate plumbing and gas, electrical and sheet metal/mechanical permits, which are billed on their own schedules. Note the sting in the tail: work started without a building permit is charged a QUADRUPLE FEE.
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