ADU · Monroe County
Can you build an ADU in Mendon, NY?
Town of Mendon has 4 districts. All districts prohibit ADUs. Check your address to confirm the district that applies to your parcel:
What the Mendon code says
Mendon has no accessory dwelling unit. Its only second-unit route is converting an existing building in RS-30, with a Planning Board special use permit, which creates co-equal dwellings; RA-5, RA-2 and RA-1 are one dwelling per lot.
Conditions the code attaches:
- No more than four units may be created in one building, each at least 450 sq ft for an efficiency, 550 for one bedroom, 800 for two and 900 for three.
- The building must have at least 2,000 sq ft of gross floor area, and a parcel with an existing single-family dwelling must be at least 1 1/2 acres.
- The conversion section sets no owner-occupancy or family requirement.
- A newly built two-family is permitted by right in RS-30, which also allows apartment houses, townhouse clusters, condominiums and cooperatives by special permit.
- Building Department: (585) 624-6066.
What the Mendon 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 |
|---|---|---|---|---|
| Residential Agricultural 5 | 5 ac | 60 / 20 / 20 ft | 35 ft | No |
| Residential Agricultural 2 | 2 ac | 60 / 20 / 20 ft | 35 ft | No |
| Residential Agricultural 1 | 1 ac | 60 / 20 / 20 ft | 35 ft | No |
| Residential Suburban 30 | 0.69 ac | 60 / 15 / 20 ft | 35 ft | No |
Residential Agricultural 5 - The lot requirement is a density, not a flat minimum, so a smaller lot can comply if the parent tract carries the density. A lot may narrow to 100 ft at the right-of-way if it opens to the full width shown at the building line.
- A lot fronting a state road owes an 80 ft front setback.
- Height is capped at two and a half storeys as well as 35 ft, so the storey count can bind before the height does.
- Minimum habitable floor area rises to 1,500 sq ft for a dwelling taller than one storey.
- The district states no lot coverage limit.
Residential Agricultural 2, Residential Agricultural 1 - The lot requirement is a density, not a flat minimum, so a smaller lot can comply if the parent tract carries the density. A lot may narrow to 50 ft at the right-of-way if it opens to the full width shown at the building line.
- A lot fronting a state road owes an 80 ft front setback.
- Height is capped at two and a half storeys as well as 35 ft, so the storey count can bind before the height does.
- Minimum habitable floor area rises to 1,500 sq ft for a dwelling taller than one storey.
- The district states no lot coverage limit.
Residential Suburban 30 - The lot requirement is a density, not a flat minimum, so a smaller lot can comply if the parent tract carries the density. A lot may narrow to 50 ft at the right-of-way if it opens to the full width shown at the building line.
- A lot fronting a state road owes an 80 ft front setback.
- Height is capped at two and a half storeys as well as 35 ft, so the storey count can bind before the height does.
- Minimum habitable floor area rises to 1,200 sq ft for a dwelling taller than one storey.
ADUs vs. short-term rentals in Mendon
Short-term rentals allowed with registration for Town of Mendon. A short-term rental in Mendon needs a revocable Town operating permit under § 208-5, and the permit is nontransferable, so a buyer of an operating rental must apply afresh rather than rely on the seller's permit. 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 minimum0.69–5 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityRG&E territory.
- Zoning codeecode360.com/29608924
- Building dept(585) 624-6066
ADU FAQ — Mendon, NY
Are ADUs allowed in Mendon, NY?
Town of Mendon has 4 districts. All districts prohibit ADUs. Check your address with the free ADU checker, or confirm with the building department at (585) 624-6066.
Do I need a special permit for an ADU in Mendon?
No. No district in Town of Mendon permits an ADU, so there is no permit to apply for. Codes change, so verify with the building department at (585) 624-6066 before ruling it out.
Can I use an ADU as a short-term rental in Mendon?
Short-term rentals allowed with registration for Town of Mendon. 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.
What an ADU costs to build in Mendon
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 Mendon, priced by size.
How we know this
- Sections analyzed
- Ch. 260 § 260-16B and D(4) RS-30 uses; Art. VII § 260-47 Residential conversions; §§ 260-13 to 260-15 RA-5, RA-2 and RA-1
- Districts confirmed
- 4 of 4 — every mapped district.
- Last reviewed
- 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 Mendon: 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 Mendon is compiled from the municipal code (last reviewed 2026-08-13) 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) 624-6066 before relying on any answer. Source: the Offsite / Aldo zoning dataset.