ADU · Monroe County
Can you build an ADU in Clarkson, NY?
Town of Clarkson has 3 districts. All districts allow ADUs with a special-use permit. Check your address to confirm the district that applies to your parcel:
What the Clarkson 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 |
|---|---|---|---|---|
| Agricultural Residential (AR) — 2 acres with 200 ft of lot width, 25% maximum lot coverage and 35 ft maximum height. Front setback 40 ft on a MINOR road and 75 ft on a MAJOR road (table note 4); side 25 ft; rear 30 ft to a dwelling or attached garage and 10 ft to any other structure (table note 1). A TWO-FAMILY DWELLING IS ALLOWED AT IDENTICAL DIMENSIONS to the single-family row (2 acres, 200 ft, same setbacks, same 25% coverage, same 35 ft height), so a second unit costs no additional LAND — but it is a SPECIALLY PERMITTED use, not a right, and so is the accessory dwelling unit. Both sit under the 'Specially Permitted Uses' block of the § 140-20.3 table rather than the 'Permitted Uses' block, and the table carries no per-row P/SP marker, so the distinction is visible only in the section header above the row. AR therefore offers two routes to a second unit at no extra acreage, each requiring a special permit and neither available as of right. A detached ADU is allowed in AR (unlike RS-10, which is internal-only), which remains the district's real advantage. AGRICULTURAL OPERATIONS ARE A SEPARATE AND MUCH LARGER ROW: 5 acres with 250 ft of width, 100 ft front, 35 ft side and 60 ft rear, and their height cap does not apply to barns, silos, water towers or tanks, windmills or other farm buildings on active farmland (table note 3). THE TABLE IS USE-KEYED, NOT DISTRICT-KEYED, AND THAT IS THE CENTRAL READING HAZARD IN THIS TOWN: each district's table lists one row per permitted use, each with its own lot size, width, setbacks, coverage and height, so 'the AR minimum lot' is meaningless without naming the use. The 2 acres recorded here is the single-family dwelling row. | 2 ac | 40 / 25 / 30 ft | 35 ft | Special permit |
| Residential Suburban — 20,000 sf (RS-20) — 20,000 sf (0.46 acres) with 100 ft of lot width, 30% maximum lot coverage and 35 ft maximum height. Front setback 40 ft on a minor road and 75 ft on a major road (table note 3); side 10 ft; rear 30 ft to a dwelling or attached garage and 10 ft to other structures (table note 1). The district name states its own minimum lot, which makes this one of the few self-documenting districts in the county. A TWO-FAMILY DWELLING IS ALLOWED ON THE SAME 20,000 SF AT THE SAME SETBACKS AND COVERAGE as a single-family — no extra land is required for the second unit — and a DETACHED ADU is allowed on top of that under § 140-23.4. SO AN RS-20 LOT CAN REACH THREE UNITS ON THE MINIMUM ACREAGE, BUT NOT AS OF RIGHT: both the two-family and the ADU are SPECIALLY PERMITTED uses under the § 140-20.4 table, so each needs its own special permit. The land is free; the approvals are not. Note that the side setback drops to 10 ft here from AR's 25 ft while the rear holds at 30 ft, so the buildable envelope narrows far less than the lot does. The ADU carries its own 10 ft side and 10 ft rear setbacks and otherwise refers to the primary use for bulk. As everywhere in this chapter the table is USE-KEYED: the figures recorded are the single-family dwelling row, and other uses permitted in RS-20 state their own dimensions. | 0.4591 ac | 40 / 10 / 30 ft | 35 ft | Special permit |
| Residential Suburban — 10,000 sf (RS-10) — 10,000 sf (0.23 acres) with 75 ft of lot width, 40% maximum lot coverage and 35 ft maximum height. Front setback 40 ft on a minor road and 75 ft on a major road (table note 3); side 10 ft; rear 30 ft to a dwelling or attached garage and 10 ft to other structures (table note 1). This is Clarkson's densest district and carries the town's highest coverage allowance at 40%. THIS DISTRICT IS THE ONE PLACE IN THE TOWN THAT PERMITS MULTIFAMILY, AND IT DOES SO IN TWO TIERS THAT ARE EASY TO CONFLATE: a multifamily dwelling of UP TO 4 UNITS needs 20,000 sf with 100 ft of width, and a multifamily dwelling of OVER 4 UNITS needs a full ACRE with 100 ft of width — both at 40% coverage but at a raised 40 FT height rather than the 35 ft that applies to one- and two-family forms, and both governed additionally by § 140-23.17. So the recorded 10,000 sf is the single-family figure and sizing a small apartment building from it would understate the land requirement by two to four times. A two-family dwelling is permitted on the same 10,000 sf as a single-family. THE ADU RULE IS NARROWER HERE THAN ELSEWHERE IN THE TOWN: in RS-10 an accessory dwelling unit may only be located WITHIN THE PRIMARY STRUCTURE, whereas AR and RS-20 permit a detached ADU — so no backyard cottage on these lots, internal conversion only. The table is USE-KEYED throughout; the figures recorded are the single-family dwelling row. | 0.2296 ac | 40 / 10 / 30 ft | 35 ft | Special permit |
ADUs vs. short-term rentals in Clarkson
Short-term rentals allowed with local rules for Town of Clarkson. CLARKSON IS THE FIRST MONROE TOWN WITH A PURPOSE-BUILT SHORT-TERM RENTAL LAW INSIDE ITS ZONING CODE, and it is the clearest STR finding in the county so far. § 140-23.21 Short-term rentals (STRs) sits in Article 23 Additional Use Regulations alongside a separate § 140-23.9 Bed-and-breakfasts, so the two are regulated as distinct uses rather than conflated. The stated purpose is explicit that the Town 'welcomes visitors' but that OVERCONCENTRATION of STRs may disrupt the peace, quiet and enjoyment of residents, and the section is framed as a balance between owners who wish to offer STRs and neighbours who do not. Operational requirements read so far: no STR is permitted on any property in violation of the Zoning Code or the NYS Uniform Fire Prevention and Building Code; the use must accommodate its MINIMUM OFF-STREET PARKING REQUIREMENT ENTIRELY ON SITE; and there is a further restriction on where off-street parking may be placed. TREAT THE PERMIT QUESTION AS OPEN: strStatus is recorded as regulated rather than registration_required precisely because no registration or permit clause was confirmed. Note also that a keyword sweep of the 52-chapter Town Code TOC found NO separate rental-licensing chapter of the Gates Ch. 148 kind, so § 140-23.21 appears to be the whole regime, but that should be confirmed when the section is read in full. New York State's 2025 statewide short-term rental registry (Ch. 99 of the Laws of 2025) obliges every host to register regardless of local law. Confirm with the Building Department at (585) 637-1145. 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 minimum0.2296–2 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityRG&E territory.
- Building dept(585) 637-1145
- Last reviewed2026-08-13
ADU FAQ — Clarkson, NY
Are ADUs allowed in Clarkson, NY?
Town of Clarkson has 3 districts. All districts allow ADUs with a special-use permit. Check your address with the free ADU checker, or confirm with the building department at (585) 637-1145.
Do I need a special permit for an ADU in Clarkson?
Yes. Every district in Town of Clarkson requires a special-use permit for an ADU rather than allowing one as of right. Check the conditions attached to it before you design.
Can I use an ADU as a short-term rental in Clarkson?
Short-term rentals allowed with local rules for Town of Clarkson. 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 Clarkson
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 Clarkson, priced by size.
More on Clarkson: Full zoning for new construction · ADU build cost · House build cost · All Monroe County towns
ADU information for Town of Clarkson 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) 637-1145 before relying on any answer. Source: Offsite / Aldo zoning dataset, municipalData.js.