ADU · Monroe County

Can you build an ADU in Brighton, NY?

Town of Brighton has 8 districts. All districts prohibit ADUs. Check your address to confirm the district that applies to your parcel:

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What the Brighton code says

Brighton's code does not allow an accessory apartment, accessory dwelling unit or in-law unit in any residential district; under § 201-12 any use the regulations do not list is prohibited.

Conditions the code attaches:

In RLL, RLA, RLB, RLC and RM the only dwelling type listed is a single-family detached dwelling, not to exceed one dwelling on each lot (§ 203-1.1A, § 203-2.1A, § 203-9A, § 203-16A, § 203-23A).
Accessory uses in those districts are limited to non-habitable items such as a pool, gazebo, shed or cabana, one private garage of up to 600 sq ft and a horticultural building of up to 336 sq ft.
RHD-2 adds two-family dwellings by right plus townhouses and garden apartments (§ 203-30A); RHD-1 adds high-rise and garden apartments as conditional uses (§ 203-37). Both are principal buildings.
PRD lists single-family attached and detached dwellings, with accessory uses limited to recreation, horticulture, maintenance buildings and solar or wind devices for residents (§ 203-146).
A dwelling unit is defined as complete housekeeping facilities for one family including any domestic servants employed on the premises (§ 201-5), counted inside that one unit.
The livable floor area limit in Ch. 205 would also cap any enlargement of a house; confirm with the Building and Planning Department at (585) 784-5250.

What the Brighton 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
RLL Residential - Large Lot	1 ac	75 / 22.5 / 60 ft	30 ft	No
RLA Residential - Low Density	0.53 ac	60 / 18.75 / 60 ft	30 ft	No
RLB Residential - Low Density	0.31 ac	40 / 13.5 / 40 ft	30 ft	No
RLC Residential - Low Density	0.26 ac	40 / 11.25 / 40 ft	30 ft	No
RM Residential - Medium Density	0.16 ac	35 / 5.5 / 40 ft	30 ft	No
PRD Planned Residential Development	5 ac	30 / 10 / 20 ft	40 ft	No
RHD-1 Residential - High Density	0.92 ac	60 / 40 / 45 ft	80 ft	No
RHD-2 Residential - High Density	0.46 ac	40 / 30 / 35 ft	40 ft	No

RLL Residential - Large Lot, RLB Residential - Low Density, RLC Residential - Low Density - Livable floor area has a maximum as well as a minimum: 1,908 sq ft plus 57 sq ft for each 1,000 sq ft of lot area, so a large house on a modest lot can fail on this cap before it fails on coverage.

The side yard is 15% of the lot width with a ceiling of 40 ft, so it shrinks on a narrower lot and grows on a wider one; a 200 ft wide lot owes 30 ft a side.
On a 13,500 sq ft lot the floor area cap comes to about 2,678 sq ft.
Incentive zoning under Chapter 209, Article II, can modify the floor area cap.
An attached garage is capped separately at 900 sq ft.

RLA Residential - Low Density - Livable floor area is capped at 1,908 sq ft plus 57 sq ft for each 1,000 sq ft of lot area, about 3,226 sq ft at the district minimum lot, which leaves a narrow band above the 1,800 sq ft minimum.

The side yard is 15% of the lot width with a ceiling of 40 ft, so it shrinks on a narrower lot and grows on a wider one; a 200 ft wide lot owes 30 ft a side.
On a 13,500 sq ft lot the floor area cap comes to about 2,678 sq ft.
Incentive zoning under Chapter 209, Article II, can modify the floor area cap.
An attached garage is capped separately at 900 sq ft.

RM Residential - Medium Density - Livable floor area has a maximum as well as a minimum: 1,908 sq ft plus 57 sq ft for each 1,000 sq ft of lot area, so a large house on a modest lot can fail on this cap before it fails on coverage.

Side yards are 10% of the lot width for one side and 25% for both together, and both grow on a wider lot.
On a 13,500 sq ft lot the floor area cap comes to about 2,678 sq ft.
Incentive zoning under Chapter 209, Article II, can modify the floor area cap.
An attached garage is capped separately at 900 sq ft.

PRD Planned Residential Development - The 5 acres is the minimum for the whole development, not for each lot, and yield is capped at six dwelling units per gross acre. The front yard is 100 ft on a state or county road and 40 ft on a Town collector street.

A semidetached lot takes 30 ft of width and 800 sq ft of livable floor area per unit; an attached lot 20 ft and 600 sq ft, 60% of what a detached house needs, with 5 ft between units.
A yard on a project boundary line that is not a street is 30 ft.
The 10 ft side yard applies only where a side yard is provided.
Each dwelling unit needs 1,200 sq ft of usable open space.
No building may contain more than five dwelling units or be longer than 150 ft.
Individual lots have no published lot area, only a width that depends on the dwelling type.

RHD-1 Residential - High Density - The land requirement is 8,000 sq ft for the first dwelling unit and 1,000 sq ft for each additional one, on a lot of at least 40,000 sq ft.

Where individual lots each hold their own unit the standard differs: a minimum lot area of 1,200 sq ft (0.0275 acres), a width of 14 ft and a depth of 80 ft, and an end unit owes a 30 ft side yard.
Each dwelling unit also needs 600 sq ft of usable open space.

RHD-2 Residential - High Density - The land requirement is 10,000 sq ft for the first dwelling unit and 2,700 sq ft for each additional one, on a lot of at least 20,000 sq ft. A density cap of 14 units per acre also applies and is what usually binds.

Where individual lots each hold their own unit the standard differs: a minimum lot area of 1,200 sq ft (0.0275 acres), a width of 14 ft and a depth of 80 ft, and an end unit owes a 30 ft side yard.
Each dwelling unit needs 600 sq ft of usable open space.

ADUs vs. short-term rentals in Brighton

No local short-term-rental law on record - which is not the same as permission for Town of Brighton. The Town of Brighton has no local short-term rental law, and that is not the same as permission. Confirm with the Building and Planning Department 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 minimum0.16–5 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityRG&E territory.
Zoning codeecode360.com/9441732
Building dept(585) 784-5250

ADU FAQ — Brighton, NY

Are ADUs allowed in Brighton, NY?

Town of Brighton has 8 districts. All districts prohibit ADUs. Check your address with the free ADU checker, or confirm with the building department at (585) 784-5250.

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

No. No district in Town of Brighton permits an ADU, so there is no permit to apply for. Codes change, so verify with the building department at (585) 784-5250 before ruling it out.

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

No local short-term-rental law on record - which is not the same as permission for Town of Brighton. 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 Brighton

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 Brighton, priced by size.

How we know this

Sections analyzed: § 201-12; § 201-5; §§ 203-1.1, 203-2.1, 203-9, 203-16, 203-23, 203-30, 203-37, 203-146
Districts confirmed: 8 of 8 — every mapped district.
Last reviewed: 2026-08-10
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 Brighton: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Monroe County · All Monroe County towns

ADU information for Town of Brighton is compiled from the municipal code (last reviewed 2026-08-10) 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 (585) 784-5250 before relying on any answer. Source: the Offsite / Aldo zoning dataset.