ADU · Monroe County
Can you build an ADU in Penfield, NY?
Town of Penfield has 8 districts. 6 districts allow ADUs with occupancy restrictions, 2 do not. Check your address to confirm the district that applies to your parcel:
What the Penfield code says
Penfield allows one in-law apartment inside a single-family home in its six single-family districts, under § 250-5.1D(1). It may be occupied only by family or in-laws of the household, never rented to anyone else, and the permission ends on a change of ownership.
Conditions the code attaches:
- The apartment may not exceed 30% of the total area of the residence.
- A building permit is required before the space is used as an in-law apartment, and an affidavit identifying the occupant must be filed before the permit issues.
- Occupancy is confirmed by notarized affidavit every three years. § 250-2.2 lists the relatives who qualify, from son or daughter to cousin and step-relatives of those degrees.
- The apartment may have its own entrance but must have an internal access point to the main house, and may not have its own driveway or garage, though an existing garage and driveway may be expanded.
- The unit must be a separate living space within the single-family dwelling, so a detached cottage is not a route. When vacant it reverts to the main household without further permitting.
- MR and TH do not list an in-law apartment, and § 250-3.1 prohibits any use not listed for a district. Building department: (585) 340-8636.
How big an ADU can be in Penfield
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.
30% of the principal dwelling
What the Penfield 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 |
|---|---|---|---|---|
| RA-2 Rural Agricultural | 2 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| CR-2 Conservation Residential | 2 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| RR-1 Rural Residential | 1 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| R-1-20 Residential | 0.46 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| R-1-15 Residential | 0.34 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| R-1-12 Residential | 0.28 ac | 50 / 10 / 30 ft | 35 ft | Occupancy restricted |
| MR Multiple Residence | — | 80 / 80 / 80 ft | 35 ft | No |
| TH Townhouse Dwelling | — | 80 / 80 / 80 ft | 35 ft | No |
RA-2 Rural Agricultural - The district sets no maximum lot coverage of any kind, so the buildable envelope comes from the lot minimum, the setbacks and the height alone. A deck or patio may sit 25 ft from the rear line rather than 30 ft.
- A covered or enclosed porch does not qualify for the shallower rear setback.
- Any other structure attached to or abutting the principal building must meet the full district setbacks.
- Multi-unit development is not a route on a single-family lot here. MR and TH are separate districts reached by rezoning.
CR-2 Conservation Residential - Decks and patios may sit 25 ft from the rear lot line rather than 30 ft. The district sets no maximum lot coverage of any kind, so the buildable envelope is controlled by the lot minimum, the setbacks and the height alone.
- A covered or enclosed porch does not get the shallower rear setback and must meet the full 30 ft.
- Any other structure attached to or abutting the principal building has to meet the full district setbacks.
- Multi-unit development is not a route on a lot here. MR and TH are separate districts reached by rezoning.
RR-1 Rural Residential - An uncovered deck or patio may sit 25 ft from the rear lot line rather than the 30 ft the house must hold. The district publishes no maximum lot coverage, so the envelope is set by the lot minimum, the setbacks and the height alone.
- A covered or enclosed porch does not qualify for the shallower rear setback.
- Every other structure attached to or abutting the principal building must meet the full district setbacks.
- Multi-unit development is not a route on a single-family lot here. MR and TH are separate districts reached by rezoning.
R-1-20 Residential - A deck or patio may sit 25 ft from the rear lot line rather than the 30 ft the house must hold. The district sets no maximum lot coverage, so the buildable envelope comes from the lot minimum, the setbacks and the height alone.
- A covered or enclosed porch does not get the shallower rear setback.
- Every other structure attached to or abutting the principal building must meet the full district setbacks.
- Multi-unit development is not a route on a single-family lot here. MR and TH are separate districts reached by rezoning.
R-1-15 Residential - No maximum lot coverage is set in this district, so the buildable envelope is governed by the lot minimum, the setbacks and the height alone. A deck or patio may sit 25 ft from the rear line rather than 30 ft.
- A covered or enclosed porch does not qualify for the shallower 25 ft rear setback.
- Any other structure attached to or abutting the principal building must meet the full district setbacks.
- Multi-unit development is not a route on a single-family lot here; the MR and TH districts are separate districts reached by rezoning.
R-1-12 Residential - Decks and patios may sit 25 ft from the rear line rather than the 30 ft required of the house, though a covered or enclosed porch does not qualify. The district states no maximum lot coverage, so the lot minimum, the setbacks and the height alone shape the envelope.
- Any other structure attached to or abutting the principal building has to meet the full district setbacks.
- Multi-unit housing is not a route on a single-family lot here. The MR and TH districts are separate districts reached by rezoning.
MR Multiple Residence - This district is reached by rezoning, and the area proposed must be served by sanitary sewers, storm sewers and public water. The 80 ft setbacks apply to the exterior property lines of the development rather than to individual lots.
- Lot size is set per unit rather than as a flat minimum: 3,500 sq ft of lot area for each apartment living unit under § 250-5.2D(1).
- Inside the development, no structure may stand closer than 50 ft to a public road right-of-way.
- A separation of 30 ft is required between any two structures.
- The 25% coverage cap is measured against the gross acreage of the development, not against a single lot.
- Height is two stories or 35 ft, whichever is less, so the story count binds first on a tall design.
- Apartment houses, multiple dwellings, two-family structures and proprietary health care facilities are permitted uses.
TH Townhouse Dwelling - Density runs on usable land: one living unit per 5,000 sq ft of usable land area, and unusable land does not count. The 80 ft setbacks are project perimeter figures rather than per-lot yards, so no structure may stand closer than 80 ft to any exterior property line.
- No more than eight individual townhouse units may sit in any one building or dwelling group.
- The district is reached by rezoning, and an area proposed for rezoning must be serviced by sanitary sewers, storm sewers and public water (§ 250-5.2A and § 250-5.3A).
- The 25% coverage cap applies to the gross acreage of the development, not to an individual lot.
- Height is two stories or 35 ft, whichever is less, so the story count can bind first on a tall design.
- Within the development, no structure may stand closer than 50 ft to a public road right-of-way or 30 ft to another structure.
- No internal front or rear setback may be less than 30 ft, and the 18 ft width describes an individual townhouse lot rather than the development parcel.
ADUs vs. short-term rentals in Penfield
No local short-term-rental law on record - which is not the same as permission for Town of Penfield. Penfield's code has no confirmed short-term rental rule. The code does state that any use not specifically set forth for a district is expressly prohibited there (§ 250-3.1), so confirm with the building 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 minimum0.28–2 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityRG&E territory.
- Zoning codeecode360.com/29271775
- Building dept(585) 340-8636
ADU FAQ — Penfield, NY
Are ADUs allowed in Penfield, NY?
Town of Penfield has 8 districts. 6 districts allow ADUs with occupancy restrictions, 2 do not. Check your address with the free ADU checker, or confirm with the building department at (585) 340-8636.
Do I need a special permit for an ADU in Penfield?
No district in Town of Penfield requires a special-use permit for an ADU - 6 districts allow ADUs with occupancy restrictions, 2 do not. Site-plan review or a building permit may still apply.
Can I use an ADU as a short-term rental in Penfield?
No local short-term-rental law on record - which is not the same as permission for Town of Penfield. 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 Penfield
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 Penfield, priced by size.
How we know this
- Sections analyzed
- Ch. 250 § 250-5.1D(1) in-law apartment; § 250-2.2 definitions; § 250-3.1; § 250-5.2B; § 250-5.3B
- Districts confirmed
- 8 of 8 — 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 Penfield: 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 Penfield 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) 340-8636 before relying on any answer. Source: the Offsite / Aldo zoning dataset.