ADU · Erie County

Can you build an ADU in Boston, NY?

Town of Boston has 11 districts. 8 districts prohibit ADUs, 1 allows them with occupancy restrictions, 1 requires a special-use permit. 1 district has incomplete data - verify with the building department at (716) 941-6113. Check your address to confirm the district that applies to your parcel:

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What the Boston code says

An accessory apartment of 640 to 800 sq ft, made inside or as an addition to a single-family house, needs a special use permit in R-2 and R-C. The owner must live in one of the two units when applying. The other districts do not allow one.

Conditions the code attaches:

No detached unit: it must be converted floor space or an addition to the house
The main unit must still meet the district minimum
Access must not be visible from the street, unless one front entrance splits inside
Three off-street parking spaces are required
One apartment per lot, and the house may not also run a bed-and-breakfast
R-3 permits two-family and multifamily dwellings by right

How big an ADU can be in Boston

Size limits are set per district, and a unit inside the house is a different standard from a detached one. These are the figures the code publishes.

Inside the principal dwelling

640 to 800 sq ft

R-2, R-C · owner-occupancy required · § 123-25B(3)(a), (b), (d)

What the Boston code indicates by district

The table below shows how each district treats ADUs, alongside the lot and setback standards that govern a second unit. District boundaries and conditions vary, so treat this as a starting point and confirm the district that applies to your parcel.

District	Min lot	Setbacks F / S / R	Max height	ADU
R-1 Single-Family Residential District	0.46 ac	50 / 10 / 30 ft	35 ft	No
R-2 Single-Family Residential District	4 ac	50 / 10 / 30 ft	35 ft	Occupancy restricted
R-3 Two-or-More Family Residential District	0.34 ac	50 / 10 / 30 ft	35 ft	No
R-A Residential-Agricultural District	3 ac	50 / 10 / 30 ft	35 ft	No
General Residence-Restricted Business District	0.34 ac	50 / 10 / 30 ft	35 ft	Special permit
Local Retail Business District	0.34 ac	50 / 0 / 30 ft	35 ft	No
General Commercial District	0.34 ac	50 / 0 / 30 ft	35 ft	No
Industrial Park Research and Development District	1 ac	50 / 15 / 25 ft	30 ft	No
General Industrial District	1 ac	50 / 15 / 25 ft	35 ft	No
Mobile Home Court District	—	—	—	No
Planned Unit Development District	100 ac	—	—	—

General Residence-Restricted Business District - Lot width is additive and sewer moves it: on public sanitary sewer, 75 ft for the first dwelling unit or other principal building and a further 25 ft for each unit beyond, capped at 200 ft. Without public sewer, add 25 ft to whatever that comes to.

The 10 ft side yard is for dwellings only: any other principal building takes 30 ft or the height of the building if greater, and 15 ft or half the height beside a lot outside a residential district
A dwelling for three or more families must stand fifty feet from any property line
The rear yard is 30 ft or the height of the principal building, whichever is greater, so the figure shown is a floor
Two principal buildings on one lot must stand 30 ft apart
The width at the front lot line must equal the width at the building line, so a flag lot is not available here

Local Retail Business District - No side yard is required for a building that is not a dwelling, but one actually provided must be at least five feet, 20 ft or the building height against a residential district boundary, and 25 ft where used for vehicular access. A dwelling takes ten feet.

Height splits by use: 30 ft for any dwelling and 35 ft for anything else
The rear yard is 30 ft or the height of the principal building, whichever is greater
A dwelling for three or more families needs 20,000 sq ft per structure plus a further 3,000 sq ft for each dwelling unit, and must stand at least 30 ft from every property line
Lot width is additive: 75 ft for the first dwelling unit or other principal building, a further 25 ft for each unit beyond, capped at 200 ft, and 25 ft more without public sanitary sewer
The width at the front lot line must equal the width at the building line, so a flag lot is not available here
A 1997 amendment marks the one- and two-family figures here as for historical purposes only, so confirm with the town before relying on them

General Commercial District - No side yard is required for a building that is not a dwelling, but one actually provided must be at least ten feet, 20 ft or the building height against a residential district boundary, 12 ft where used for vehicular access and 25 ft where used for both.

A dwelling takes ten feet on the side
The rear yard is 30 ft or the height of the principal building, whichever is greater
A dwelling for three or more families needs 20,000 sq ft per structure plus a further 3,000 sq ft for each dwelling unit, and must stand at least 30 ft from every property line
Lot width is additive: 75 ft for the first dwelling unit or other principal building, a further 25 ft for each unit beyond, capped at 200 ft, and 25 ft more without public sanitary sewer
A 1997 amendment marks the one- and two-family figures here as for historical purposes only, so confirm with the town before relying on them

Industrial Park Research and Development District - The 30 ft height is the by-right ceiling, and the section says so in terms: above it a special permit from the Town Board is needed, with no upper figure named for that case.

The 50 ft front yard rises to sixty where the lot lies opposite a residential district or where the front yard holds accessory parking
The 15 ft side yard rises to fifty, or the height of the principal building if greater, against a residential district boundary, and the rear yard follows the side-yard figure there
Retail, restaurant and commercial recreation uses are accessory only, filling no more than 15% of the principal building's gross floor area and planned as an integral part of it

General Industrial District - The 35 ft height is the by-right ceiling, and the section says so in terms: above it a special permit from the Town Board is needed, with no upper figure named for that case.

The 50 ft front yard rises to sixty where the lot lies opposite a residential district or where the front yard holds accessory parking
The 15 ft side yard rises to seventy-five, or the height of the principal building if greater, against a residential district boundary, and the rear yard follows the side-yard figure there

Mobile Home Court District - Lot size, height and yards inside a licensed mobile home court are set by the Town's Mobile Home Court Law in Ch. 70 of the Town Code rather than by the zoning chapter.

Planned Unit Development District - Density is four dwelling units per gross acre, and gross acres count developable land only: wetlands and streams come out first, so a wet parcel yields far fewer units than its deed acreage suggests.

At least 30% of the site must be kept as open space
The 100 acre threshold may be relaxed by the Planning Board where the applicant shows the objectives are met and the land is contiguous to an existing planned unit development
Yards, height and coverage are settled in the approved plan rather than published in advance

ADUs vs. short-term rentals in Boston

No local short-term-rental law on record - which is not the same as permission for Town of Boston. The town has no local short-term rental law. That is not the same as permission, so confirm with the town before counting on renting a home short term. These are separate questions from whether you can build an ADU — a unit you're allowed to add isn't automatically one you're allowed to rent nightly, so check both.

Good to know

Residential lot minimum0.34–4 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityNational Grid territory.
Zoning codeecode360.com/9002443
Building dept(716) 941-6113

ADU FAQ — Boston, NY

Are ADUs allowed in Boston, NY?

Do I need a special permit for an ADU in Boston?

It depends on the district: 1 of 11 require a special-use permit, the rest do not. Check the district that applies to your parcel before you design.

Can I use an ADU as a short-term rental in Boston?

No local short-term-rental law on record - which is not the same as permission for Town of Boston. ADU occupancy and short-term-rental rules are separate: an ADU you can build isn't automatically one you can rent nightly. Confirm both before you count on STR income.

Run the free ADU check for your parcel →

What an ADU costs to build in Boston

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $200k–260k at a standard finish, and the per-square-foot rate comes in above a full house because the kitchen, bath, panel and heating plant cost the same either way. See the full cost to build an ADU in Boston, priced by size.

How we know this

Sections analyzed: § 123-25B(3) · § 123-64B(1) · §§ 123-32B(1), 123-71A(1), 123-78A(1) · § 123-17
Districts confirmed: 10 of 11 — 1 not yet analyzed, so this page does not answer for it.
Last reviewed: 2026-09-10
Not covered here: Overlay districts, the zoning map, and any conditions attached to an individual parcel. Size limits and owner-occupancy terms sit in the code section above, not in this summary.

More on Boston: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Erie County · All Erie County towns

ADU information for Town of Boston is compiled from the municipal code (last reviewed 2026-09-10) and provided for decision-support only — not legal or architectural advice. ADU eligibility, size, owner-occupancy and permit conditions vary by district and often carry exceptions; verify with the building department at (716) 941-6113 before relying on any answer. Source: the Offsite / Aldo zoning dataset.