Jeffersonville · ADU cost
What it costs to build an ADU in Jeffersonville, NY
An 800 sq ft accessory dwelling unit in Jeffersonville runs roughly $190k–250k, or about $238–312/sq ft, and that per-square-foot figure sits deliberately above the $195–256/sq ft a full house costs here. An ADU still needs one whole kitchen, one whole bath, its own service panel and its own heating plant no matter how small you draw it, and those costs do not shrink with the floor plan, so they land on half the square footage and push the rate up. Whether the village will let you build one is a separate question from what it costs, and it gets answered parcel by parcel rather than townwide, since the Village of Jeffersonville maps 3 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
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ADU cost by size in Jeffersonville
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Sullivan County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $316–$414 | $125k–165k |
| 600 sq ft | One bedroom | $264–$346 | $160k–210k |
| 800 sq ft | One bedroom, larger | $238–$312 | $190k–250k |
| 1,000 sq ft | Two bedroom | $223–$292 | $225k–290k |
400 sq ft — One room plus a bath. Garage conversions and small backyard cottages land here.
600 sq ft — The most common detached build - a real bedroom, full kitchen, one bath.
800 sq ft — Room for a proper living area. Still a single bath and one kitchen.
1,000 sq ft — About as large as most codes allow an accessory unit to go.
Why the rate is higher than a house
The systems below are priced for an 800 sq ft unit. The middle column is what each system would cost if it simply shrank with the floor plan; the left column is what it actually costs once you account for the equipment a dwelling needs one of regardless of size. The gap between the two columns is the whole reason small builds price the way they do.
| System | $ / sq ft in an ADU | If it scaled with floor area | Fixed per unit |
|---|---|---|---|
| Site work | $7–$10 | $7 | — |
| Foundation | $16–$22 | $16 | — |
| Framing | $24–$30 | $24 | — |
| Envelope - roof, siding, windows | $30–$39 | $30 | — |
| Plumbing | $26–$32 | $16 | 55% |
| Electrical | $18–$23 | $12 | 35% |
| HVAC | $22–$27 | $14 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $31–$41 | $26 | 15% |
| Millwork & cabinetry | $18–$26 | $10 | 55% |
The fixed-per-unit share is a modeling assumption, not a figure from the code: it is our estimate of how much of each system's budget buys equipment a dwelling needs exactly one of - a kitchen rough-in, a bath group, a service panel, a heating plant - and therefore does not shrink when the unit does. Site work, foundation, framing, envelope and insulation are treated as scaling straight with floor area, which understates the premium slightly, because a small building carries more envelope per square foot of floor than a large one.
What the Jeffersonville code says about accessory units
Whether you can build one, and how large, is decided by the district your parcel sits in rather than by the town as a whole. The table shows how each mapped district treats ADUs alongside the lot and setback standards a second unit still has to fit inside. District boundaries and conditions vary, so treat it as a starting point and confirm the district that applies to your parcel.
| District | Min lot | Setbacks F / S / R | Max height | ADU |
|---|---|---|---|---|
| Residential Settlement District | 0.23 ac | 20 / 10 / 25 ft | 30 ft | No |
| Development District | 0.46 ac | 40 / 15 / 20 ft | 50 ft | No |
| Commercial District | 0.11 ac | 5 / 5 / 10 ft | 50 ft | No |
Residential Settlement District - A home in the RS District needs 10,000 square feet with public sewer and water, on a lot 75 feet wide and 100 feet deep, set back 20 feet at the front, 10 feet at one side with 25 feet for both sides, and 25 feet at the rear, no taller than 2.5 stories or 30 feet.
- Without public sewer and water the minimum lot area is 40,000 square feet.
- Lot coverage is the lesser of 50% or 10,000 square feet, counting buildings and structures and leaving out parking areas and driveways.
- Lot area applies to each dwelling unit, so a two-family dwelling, which is a special use here, needs the equivalent of two minimum sized lots.
- Where an unimproved lot sits between improved lots whose buildings stand within the required front yard, the front yard drops to the average depth of the two nearest front yards.
- A yard bordering a lake or pond is at least 100 feet deep and one bordering a stream or creek at least 50 feet deep, measured from the water rather than from a lot line.
- A detached accessory structure stands at least 5 feet from the side and rear lot lines and no closer to the street than the principal structure.
Development District - A home in the DD District needs 20,000 square feet with public sewer and water, on a lot 100 feet wide and 100 feet deep, set back 40 feet at the front, 15 feet at one side with 40 feet for both sides, and 20 feet at the rear, no taller than 3 stories or 50 feet.
- Without public sewer and water the minimum lot area is 40,000 square feet.
- Lot coverage of 15% counts buildings and structures and leaves out parking areas and driveways.
- Lot area applies to each dwelling unit, so a two-family dwelling needs the equivalent of two minimum sized lots.
- An individual mobile home site in a manufactured home park may be as small as 10,000 square feet, and every manufactured home is at least 12 feet wide with 850 square feet of living area.
- A yard bordering a lake or pond is at least 100 feet deep and one bordering a stream or creek at least 50 feet deep, measured from the water rather than from a lot line.
- A detached accessory structure stands at least 5 feet from the side and rear lot lines and no closer to the street than the principal structure.
Commercial District - A building in the CM District needs 5,000 square feet of lot, 50 feet wide and 75 feet deep, set back 5 feet at the front, 5 feet at one side with 10 feet for both sides, and 10 feet at the rear, no taller than 3 stories or 50 feet.
- Lot coverage is the lesser of 75% or 10,000 square feet, counting buildings and structures and leaving out parking areas and driveways.
- The district is restricted to areas where public sewage collection and treatment services are available.
- Where a use here abuts a residential district at the lot line or on the same street, it meets that district's minimum yards where they abut.
- Multifamily housing is a special use on centralized sewage and water, with at most 6 dwellings in a building and no less than 50% of the tract left as open space.
- A structure over 50 feet is a special use and stands back from adjoining properties no less than the height of the structure.
- A detached accessory structure stands at least 5 feet from the side and rear lot lines and no closer to the street than the principal structure.
Size limits on record in Jeffersonville
Where the code states a size cap, it decides which row of the cost table above actually applies to you. These are the caps recorded for Jeffersonville:
- Residential Settlement DistrictIn RS that means 20,000 sq ft with public sewer and water, and 40,000 sq ft without.
- Development DistrictIn RS that means 20,000 sq ft with public sewer and water, and 40,000 sq ft without.
- Commercial DistrictIn RS that means 20,000 sq ft with public sewer and water, and 40,000 sq ft without.
Costs an ADU adds that a house does not
- Septic and water A second dwelling adds bedrooms to the design flow, which on an unsewered parcel often means expanding or replacing the existing system rather than tapping it. This is the single most common reason an ADU budget moves after design, and it is site-specific enough that no model should quote it - get it evaluated early.
- Utility service NYSEG territory. A detached unit needs power run to it, and whether it goes on its own meter or subfeeds the main house changes both the cost and the permit path.
- Access and parking Many codes require an added parking space for the accessory unit, and a detached unit usually needs a driveway extension or a path, both of which count against a lot-coverage or impervious-surface cap.
- Short-term rentalsNo local short-term-rental law on record - which is not the same as permission. As of June 2026 the Village of Jeffersonville has no local short-term rental law. That is not the same as permission, so confirm with the building department before counting on renting short term. Separate question from whether you can build the unit.
- Zoning codevillageofjeffersonvilleny.com/wp-content/uploads/2017/07/Zoning-and-Subdivision-Law.pdf
- Building dept(845) 482-5390
Sizing up a specific parcel in Jeffersonville?
Aldo pulls the exact zoning district, setbacks, and build feasibility for any parcel — before you buy. Enter your email to open Aldo and run your free report.
Building a full house instead?
A standard-finish house in Jeffersonville runs $195–256/sq ft, about $350k–460k at 1,800 sq ft . See what it costs to build a house in Jeffersonville.
ADU cost in nearby towns
All Sullivan County towns: Bethel · Callicoon · Cochecton · Delaware · Fallsburg · Forestburgh · Fremont · Highland · Liberty · Lumberland · Mamakating · Neversink · Rockland · Thompson · Tusten · Bloomingburg (Village) · Liberty (Village) · Monticello (Village) · Woodridge (Village)
More on Jeffersonville: Can you build an ADU here? · Zoning for new construction · Sullivan County build cost
ADU cost in Jeffersonville: common questions
How much does it cost to build an ADU in Jeffersonville, NY?
An 800 sq ft accessory dwelling unit in Village of Jeffersonville runs roughly $190k–250k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $125k–165k. Those are structure costs on an easy site and do not include the septic, water or electrical service work a second unit often triggers.
Why does an ADU cost more per square foot than a house in Jeffersonville?
Because a lot of a dwelling's cost is per dwelling, not per square foot. One kitchen, one bath group, one service panel and one heating plant cost about the same in an 800 sq ft cottage as in a 1,800 sq ft house, so on the smaller unit they get spread over less than half the floor area. That is why an ADU here prices at $238–312/sq ft against $195–256/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Jeffersonville?
Village of Jeffersonville has 3 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (845) 482-5390 before you spend money on design.
Can I rent an ADU in Jeffersonville short term?
No local short-term-rental law on record - which is not the same as permission for Village of Jeffersonville. ADU rules and short-term-rental rules are set separately, so a unit you are allowed to build is not automatically one you are allowed to rent nightly. Confirm both before you underwrite the build on short-term-rental income.
ADU costs are modeled estimates in current 2026 dollars at the Sullivan County regional index, general-contractor margin included, derived from Offsite's cost engine with a stated adjustment for the equipment a dwelling needs one of regardless of size. They are planning numbers for decision-support only - not a bid, quote, or guarantee, and not legal, architectural or engineering advice. They cover the structure and exclude septic expansion, utility service runs, site work beyond a flat and clear pad, and permit fees. ADU eligibility, size, owner-occupancy and permit conditions in the Village of Jeffersonville vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-10-07; verify with the building department at (845) 482-5390 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.