Yes: Newton allows one ADU by right on any lot with a single- or two-family house in every zoning district, and on any residential lot in the SR, MR and BU1-4 districts, under Zoning Ordinance Sec. 6.7.1 as rewritten by Ordinance No. C-62 (City Council, April 22, 2025). An internal or detached ADU may be 1,000 sq ft or 50% of the combined floor area, whichever is less, with only a building permit; 1,200 sq ft is by right for a house or accessory building at least 4 years old (or a detached unit whose owner lives on site), and the City Council can grant a special permit up to 1,200 sq ft internal or 1,500 sq ft detached. A detached unit no taller than 1.5 stories and 22 ft needs only 5-ft side and rear setbacks; no parking is added, by-right units carry no owner-occupancy test, and rentals must run 30 days or more. Permits cost $20 per $1,000 of construction cost through Inspectional Services, there are no impact fees, and the city's Backyard Blueprints gallery of pre-reviewed detached ADU plans is due in December 2026. The state's Protected Use ADU (900 sq ft or half the house, G.L. c. 40A s. 3; 760 CMR 71) is the floor; Newton's ordinance goes above it.
Zoning & Size Requirements [1][2][3][4][5][6]
Yes — Newton allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current Massachusetts and Newton zoning rules.
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| Allowed Zones | Any lot with a Single-Family Detached or Two-Family Detached house in every zoning district, plus any lot with a residential building in the Single Residence (SR1-3), Multi Residence (MR1-4) and Business 1-4 districts (Sec. 6.7.1.B, D.1, E.1; Ord. C-62). State Protected Use ADU rights (G.L. c. 40A s. 3; 760 CMR 71) apply wherever single-family use is allowed. Historically significant carriage houses and barns may hold an ADU by right without the size, height or setback limits (Sec. 6.7.1.E.6). |
| Max Size (Detached) | 1,000 sq ft or 50% of the combined gross floor area of house plus ADU, whichever is less, by right (Sec. 6.7.1.E.2); 1,001-1,200 sq ft by right if the unit is in an accessory building with a final permit sign-off at least 4 years old (E.2.c) or the owner lives in the house or ADU and files an annual certification (E.2.d); up to 1,500 sq ft by City Council special permit (E.2.b). These caps are local; the state Protected Use size is 900 sq ft or half the main house. |
| Max Size (Attached) | Internal ADU: 1,000 sq ft or 50% of the whole house's gross floor area, whichever is less, by right (Sec. 6.7.1.D.2); 1,001-1,200 sq ft by right if the house's certificate of occupancy is at least 4 years old (D.2.c); up to 1,200 sq ft by special permit in a newer house (D.2.b). Gross floor area counts every story of code-compliant ceiling height including a basement, but not garage parking, attics, crawl spaces or enclosed porches (C.3). |
| Max Size (JADU) | N/A: Massachusetts and Newton have no junior ADU category; a unit carved out of the house is an Internal ADU under Sec. 6.7.1.D. |
| Max Height | Detached ADU: up to 2.5 stories or 36 ft with the setbacks of a single-family house in the district (Sec. 6.7.1.E.3; Planning FAQ), or no more than 1.5 stories and 22 ft to use the 5-ft accessory-building setbacks (E.4). Detached ADUs are exempt from the 700 sq ft footprint cap on other accessory buildings (Planning FAQ); dormer rules in Sec. 1.5.4.G apply. |
| Max Units | 1 ADU per lot (Sec. 6.7.1.C.2); it cannot be held in separate ownership or condo-ed from the main house (C.1), and a certified copy of the ISD determination must be recorded at the Middlesex South Registry of Deeds before a certificate of occupancy issues (C.7). |
Setback Requirements [1][2][3][4][5][6]
Newton requires a rear setback of about 5 ft for a detached ADU, and parking requirements vary by unit size or location. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 5 ft for a detached ADU of no more than 1.5 stories and 22 ft (accessory-building setback, Sec. 3.4.3 via Sec. 6.7.1.E.4; Planning FAQ); a taller unit meets the single-family rear setback for the district (ISD Zoning Chart: 40 ft SR1, 30 ft SR2/SR3, 15-30 ft MR on post-1953 lots; 25 ft on older SR lots). The 1.5-story setback can be reduced by special permit (E.4). |
| Side Setback | 5 ft for a detached ADU of no more than 1.5 stories and 22 ft (Sec. 6.7.1.E.4; Planning FAQ); a taller unit meets the single-family side setback for the district (ISD Zoning Chart: 20 ft SR1, 15 ft SR2, 10 ft SR3, 7.5-10 ft MR on post-1953 lots; 7.5-12.5 ft on older lots). The unit must also keep the accessory-building separation from the main house in Sec. 3.4.3.A.2 (E.5). |
| Front Setback | Same front setback as a single-family house in the district for every detached ADU, including the 1.5-story type (Sec. 6.7.1.E.3-E.4; Planning FAQ): 25 ft in SR1 and 15 ft in the SR2, SR3 and MR districts per the ISD Zoning Chart. An internal ADU adds no setback. |
| Parking Required | None: no additional parking is required for an ADU (Sec. 6.7.1.C.5); if a space is added it must be screened from abutters. This is more generous than the state rule, which allows at most one space and none within 0.5 mile of a transit station (760 CMR 71.03(2)(b)). |
| Owner Occupancy | Not required for by-right ADUs, and the state bars it for Protected Use units (760 CMR 71.03(2)(a)). Exceptions: a detached ADU of 1,001-1,200 sq ft built by right under Sec. 6.7.1.E.2.d requires the owner (or a trust/LLC beneficial owner) to live in the house or ADU, with a sworn certification each January and notice to ISD within 30 days of a sale; the City Council may attach it to a special permit; pre-2025 ADUs that do not meet current rules keep their old condition (Planning FAQ). |
| Min Lot Size | No ADU-specific minimum lot size in Sec. 6.7.1, and 760 CMR 71.03(3)(b)2 bars one for a Protected Use ADU; the district's lot-coverage, open-space and FAR limits still apply to a detached unit (Sec. 6.7.1.C.6; ISD Zoning Chart, e.g. SR2 20% coverage / 65% open space on post-1953 lots). |
Permit Process & Fees [7][8][9][10]
An ADU permit in Newton goes through a ministerial, by-right review. Review time: not published: ISD posts no review target for a building permit; a special permit adds a City Council public hearing. Confirm current timing with the Current Planning Division. Fees range from $20 per $1,000 of estimated construction cost, rounded up, $50 minimum, for each of the building, electrical, plumbing and gas permits (ISD Permit Fee Schedule, updated Jan 1, 2026): about $6,000 for a $300,000 ADU building permit. Special-permit fees are separate.
| Approval Process | By-right ADUs (up to 1,000 sq ft, or 1,200 sq ft under Sec. 6.7.1.D.2.c/E.2.c-d): building permit only, filed online through the NewGov portal with Inspectional Services (ISD); the ISD determination is then recorded at the Registry of Deeds before the certificate of occupancy. Larger units (internal to 1,200 sq ft in a newer house; detached to 1,500 sq ft) or reduced setbacks need a City Council special permit through the Current Planning Division, judged on size and location, screening and exterior design (Sec. 6.7.1.F). Historic carriage-house conversions go through the Historical Commission. |
| Review Timeline | Not published: ISD posts no review target for a building permit; a special permit adds a City Council public hearing. Confirm current timing with the Current Planning Division. |
| Permit Fees | $20 per $1,000 of estimated construction cost, rounded up, $50 minimum, for each of the building, electrical, plumbing and gas permits (ISD Permit Fee Schedule, updated Jan 1, 2026): about $6,000 for a $300,000 ADU building permit. Special-permit fees are separate. |
| Impact Fees | None: Newton's ISD fee schedule lists no impact or linkage fee for a residential permit, and 760 CMR 71.03(3)(b)6 bars ADU-only impact fees. Water and sewer connection charges for a new detached unit: confirm with DPW Utilities. |
| Plan Check | Plan review is part of the building permit; ISD's Building Permit Application Checklist calls for a plot plan with average grade, the FAR worksheet, construction-control documents for stamped plans, energy-code and homeowner affidavits, and a final cost affidavit before the certificate of occupancy. |
| Pre-Approved Plans | Coming: the city's Backyard Blueprints competition (AARP Community Challenge grant) is collecting permit-ready detached ADU designs until Oct 19, 2026, with a public vote in November and a gallery of pre-reviewed plans sold at a flat designer fee due mid-December 2026 (Planning page, updated Sept 16, 2026). No plans are available yet. |
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Construction Costs [11][12][13]
Building an ADU in Newton typically costs $250,000-$450,000 ($275-$450 per sq ft); a garage conversion runs $100,000-$250,000.
See what this means for your lot — ask Newton ADU builders for a quote →
| Average Build Cost | $250,000-$450,000 |
| Cost per Sq Ft | $275-$450 |
| Garage Conversion | $100,000-$250,000 |
| Prefab ADU (Installed) | $250,000-$480,000 |
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Rental Income Potential [14][15][16]
A 2-bedroom ADU in Newton rents for around $3,100-$4,300/mo, an estimated 9-14% gross rent yield (estimate).
| Avg Rent (1 Bedroom) | $2,600-$3,600/mo |
| Avg Rent (2 Bedroom) | $3,100-$4,300/mo |
| Short-Term Rental | No: once a lot has an ADU, both the ADU and the main house must be rented or occupied for 30 days or more (Sec. 6.7.1.C.4), and Newton's short-term rental ordinance (Ch. 20 Art. IX; Zoning Sec. |
| Est. Annual ROI | 9-14% gross rent yield (estimate) |
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Recent Law Changes
What's Changed Recently
- 2026-09-20 re-verification: every rule re-read from Ordinance No. C-62 (Sec. 6.7.1 as adopted April 22, 2025), the Planning ADU page (updated Sept 16, 2026), the ISD Permit Fee Schedule (Jan 1, 2026) and the ISD Zoning Chart; code section corrected from 6.2.4 to 6.7.1; permit fee ($20 per $1,000), no impact fees, front setbacks, the gross-floor-area rule and the Backyard Blueprints plan program added; rents re-based on HUD FY2027 Small Area FMRs.
- Sept 2026: Backyard Blueprints, Newton's public detached-ADU design competition (AARP Community Challenge grant): submissions to Oct 19, 2026, public vote early November, gallery of pre-reviewed flat-fee plans due mid-December 2026.
- April 22, 2025: Ordinance No. C-62 (dockets #369-24, 24-0, and #369-24(2), 18-6; signed by the Mayor May 2025) replaced Sec. 6.7.1 'Accessory Apartments' with 'Accessory Dwelling Units': 1,000 sq ft/50% by right for single- and two-family lots in every district, 1,200 sq ft by right for 4-year-old buildings or owner-occupied detached units, 1,500 sq ft detached by special permit, 5-ft setbacks at 1.5 stories/22 ft, no parking, 30-day minimum rental, historic carriage houses by right; the old owner-occupancy affidavit, 15-ft carriage-house separation and Historic District bar were deleted.
- Feb 2, 2025: Affordable Homes Act s. 8 (Ch. 150 of the Acts of 2024) amended G.L. c. 40A s. 3: one Protected Use ADU of up to 900 sq ft or 50% of the main house by right on single-family lots, no owner-occupancy, no special permit; 760 CMR 71.00 in force Jan 31, 2025. Newton's 1,000/1,200/1,500 sq ft tiers are local rules above that floor.
- Jan 2, 2020: Newton short-term rental ordinance (Ch. 20 Art. IX; Zoning Sec. 6.7.5) in force: registration, fire inspection, primary residence only; ADUs are excluded by the 30-day minimum in Sec. 6.7.1.C.4.
Tips for Building an ADU in Newton
- Size math: gross floor area under Sec. 6.7.1.C.3 counts every story with code-compliant ceiling height, including a finished basement, but not garage parking, attics, crawl spaces or enclosed porches. An internal ADU may take up to half the whole house: an 1,800 sq ft house (basement included) allows a 900 sq ft basement unit; 2,000 sq ft or more allows the full 1,000 sq ft.
- Stay at 900 sq ft or half the main house and the unit is also a state Protected Use ADU (G.L. c. 40A s. 3; 760 CMR 71.03), which limits what conditions the city can attach; 901-1,000 sq ft is by right only under Newton's own ordinance.
- The by-right 1,200 sq ft tiers have paperwork: an internal unit needs a house certificate of occupancy at least 4 years old; a detached unit needs either an accessory building with a 4-year-old final sign-off or owner occupancy with a sworn certification filed every January and notice to ISD within 30 days of a sale (Sec. 6.7.1.D.2.c, E.2.c-d).
- Keep a backyard cottage to 1.5 stories and 22 ft to use 5-ft side and rear setbacks; anything taller (up to 2.5 stories/36 ft) must meet the single-family setbacks, e.g. 15 ft front, 15 ft side and 30 ft rear on a post-1953 SR2 lot per the ISD Zoning Chart. Detached ADUs are exempt from the 700 sq ft accessory-building footprint cap.
- Fee math: permits are $20 per $1,000 of estimated cost rounded up, $50 minimum. A $300,000 detached ADU pays about $6,000 for the building permit plus $20 per $1,000 for the electrical, plumbing and gas permits on their own costs; there are no impact or linkage fees.
- Before the certificate of occupancy you must record a certified copy of the ISD determination at the Middlesex South Registry of Deeds and file copies with ISD and the Assessing Department (Sec. 6.7.1.C.7); the ADU can never be sold separately.
- Rentals must run 30 days or more for both the ADU and the main house once an ADU exists (Sec. 6.7.1.C.4), and Newton's STR registry covers only an operator's primary residence, so plan on long-term leases. HUD FY2027 Small Area FMRs for Newton ZIPs: 1BR $2,610 (West Newton 02465) to $3,630 (Newton Highlands 02461); 2BR $3,120-$4,340.
- Historic carriage houses, barns and garages deemed historically significant under Sec. 22-50 can become an ADU by right with no size, height or setback limits, but exterior changes go to the Historical Commission (Sec. 6.7.1.E.6); a non-historic carriage house is capped at 1,200 sq ft.
- Cost basis (2026-09-20): avg build cost $250,000-$450,000 = a 900-1,000 sq ft detached stick-built unit per Dwelly (Mar 2026: $275-$450 per sq ft; 1,000 sq ft $275,000-$450,000) and Horizon ADU (Jul 2026: detached 900 sq ft $250,000-$360,000) | garage or basement conversion $100,000-$250,000 (Horizon) | prefab $250,000-$480,000 installed for 650-750 sq ft in Greater Boston (ADU Wizard, 2026 edition). Design ($3,000-$8,000) and site work are extra.
- Watch the Backyard Blueprints gallery (mid-December 2026): pre-reviewed detached plans in 1, 1.5, 2 and 2.5-story types sold at a flat designer fee, meant to cut design cost and speed ISD review; each plan still needs a site-specific plot plan and zoning check.
- Cost basis (2026-09-20 re-verification): short term allowed: No: once a lot has an ADU, both the ADU and the main house must be rented or occupied for 30 days or more (Sec. 6.7.1.C.4), and Newton's short-term rental ordinance (Ch. 20 Art. IX; Zoning Sec. 6.7.5, in force Jan 2, 2020) registers only an operator's primary residence.
ADU Builders in Newton
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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.
- Ordinance No. C-62, Chapter 30 Sec. 6.7.1 Accessory Dwelling Units (ADUs), City of Newton In City Council, April 22, 2025 government — Accessed 2026-09-20
- Accessory Dwelling Units (ADU), City of Newton Planning (Backyard Blueprints; ADU FAQs), updated Sept 16, 2026 government — Accessed 2026-09-20
- Zoning Chart (district setbacks, lot coverage, open space, FAR), Newton Inspectional Services government — Accessed 2026-09-20
- ADU Informational Brochure, City of Newton Planning and Inspectional Services government — Accessed 2026-09-20
- 760 CMR 71.03, Regulation of Protected Use ADUs in Single-family Residential Zoning Districts Government Data — Accessed 2026-09-19
- City Council revises rules for Accessory Dwelling Units, Fig City News (Apr 27, 2025) News Source — Accessed 2026-09-19
- Permit Fee Schedule (effective July 1, 2015, updated January 1, 2026), Newton Inspectional Services government — Accessed 2026-09-20
- Forms & Resources (Building Permit Application Checklist, affidavits, FAR worksheet), Newton Inspectional Services government — Accessed 2026-09-20
- ADU's - Accessory Dwelling Units (permit application link), Newton Inspectional Services government — Accessed 2026-09-20
- Ordinance No. C-62, Sec. 6.7.1.C.7 (Registry of Deeds recording) and 6.7.1.F (special permit criteria) government — Accessed 2026-09-20
- Dwelly, How Much Does an ADU Cost in Massachusetts in 2026? (Mar 7, 2026) industry — Accessed 2026-09-20
- Horizon ADU, How Much Does a 900 Sq Ft ADU Cost in Massachusetts? (Jul 24, 2026) industry — Accessed 2026-09-20
- ADU Wizard, How Much Does an ADU Cost in Massachusetts in 2026? industry — Accessed 2026-09-20
- HUD FY2027 Small Area Fair Market Rent Schedule (Newton ZIPs 02458-02468) Government Data — Accessed 2026-09-20
- HUD FY2027 Fair Market Rents, Boston-Cambridge-Quincy, MA-NH HMFA Government Data — Accessed 2026-09-20
- Short Term Rental Information (Ch. 20 Art. IX; Zoning Sec. 6.7.5), Newton Inspectional Services government — Accessed 2026-09-20
Frequently Asked Questions
Can I build an ADU in Newton?
Yes. ADUs are allowed in Any lot with a Single-Family Detached or Two-Family Detached house in every zoning district, plus any lot with a residential building in the Single Residence (SR1-3), Multi Residence (MR1-4) and Business 1-4 districts (Sec. 6.7.1.B, D.1, E.1; Ord. C-62). State Protected Use ADU rights (G.L. c. 40A s. 3; 760 CMR 71) apply wherever single-family use is allowed. Historically significant carriage houses and barns may hold an ADU by right without the size, height or setback limits (Sec. 6.7.1.E.6). in Newton. The maximum size for a detached ADU is 1,000 sq ft or 50% of the combined gross floor area of house plus ADU, whichever is less, by right (Sec. 6.7.1.E.2); 1,001-1,200 sq ft by right if the unit is in an accessory building with a final permit sign-off at least 4 years old (E.2.c) or the owner lives in the house or ADU and files an annual certification (E.2.d); up to 1,500 sq ft by City Council special permit (E.2.b). These caps are local; the state Protected Use size is 900 sq ft or half the main house.. Owner-occupancy is not required, so you can rent out the ADU.
How much does an ADU cost in Newton?
ADU construction in Newton typically costs $250,000-$450,000. Garage conversions run $100,000-$250,000, and prefab ADUs cost $250,000-$480,000.
How much can I rent an ADU for in Newton?
Average ADU rents in Newton are $2,600-$3,600/mo for a 1-bedroom and $3,100-$4,300/mo for a 2-bedroom unit.
Do I need parking for an ADU in Newton?
None: no additional parking is required for an ADU (Sec. 6.7.1.C.5); if a space is added it must be screened from abutters. This is more generous than the state rule, which allows at most one space and none within 0.5 mile of a transit station (760 CMR 71.03(2)(b)).. Check with Newton 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 Newton?
Newton does not publish a standard ADU review timeline. ISD posts no review target for a building permit; a special permit adds a City Council public hearing. Confirm current timing with the Current Planning Division. Fees range from $20 per $1,000 of estimated construction cost, rounded up, $50 minimum, for each of the building, electrical, plumbing and gas permits (ISD Permit Fee Schedule, updated Jan 1, 2026): about $6,000 for a $300,000 ADU building permit. Special-permit fees are separate.
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