Stony Point · ADU cost
What it costs to build an ADU in Stony Point, NY
An 800 sq ft accessory dwelling unit in Stony Point runs roughly $225k–295k, or about $280–366/sq ft, and that per-square-foot figure sits deliberately above the $229–300/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 town 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 Town of Stony Point maps 12 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 Stony Point
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Rockland County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $371–$485 | $150k–195k |
| 600 sq ft | One bedroom | $310–$406 | $185k–245k |
| 800 sq ft | One bedroom, larger | $280–$366 | $225k–295k |
| 1,000 sq ft | Two bedroom | $261–$342 | $260k–340k |
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 | $8–$12 | $8 | — |
| Foundation | $18–$26 | $18 | — |
| Framing | $29–$36 | $29 | — |
| Envelope - roof, siding, windows | $36–$46 | $36 | — |
| Plumbing | $31–$38 | $18 | 55% |
| Electrical | $21–$26 | $14 | 35% |
| HVAC | $26–$32 | $16 | 45% |
| Insulation | $8–$10 | $8 | — |
| Interior finishes | $36–$48 | $31 | 15% |
| Millwork & cabinetry | $21–$31 | $12 | 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 Stony Point 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 |
|---|---|---|---|---|
| Suburban Residential - Rural | 4.59 ac | 50 / 30 / 50 ft | 35 ft | Special permit |
| Rural Residential | 1.15 ac | 50 / 25 / 50 ft | 35 ft | Special permit |
| One-Family Residential | 0.34 ac | 35 / 15 / 35 ft | 35 ft | Special permit |
| Waterfront Residential | 0.11 ac | 25 / 10 / 20 ft | 35 ft | No |
| Manufactured Housing Community | 0.11 ac | 10 / 20 / 20 ft | 15 ft | No |
| Senior Residential Community | 3.44 ac | 50 / 50 / 50 ft | 35 ft | No |
| Public Waterfront | 1 ac | 50 / 50 / 50 ft | 45 ft | No |
| Business | 0.23 ac | 15 / 0 / 25 ft | 30 ft | No |
| Office | 1.84 ac | 20 / 50 / 60 ft | 45 ft | No |
| Light Industrial | 0.92 ac | 15 / 50 / 50 ft | 45 ft | No |
| Light Industrial 2 | 0.92 ac | 15 / 50 / 50 ft | 45 ft | No |
| Route 9W Rural Business/Research | 0.92 ac | 15 / 50 / 50 ft | 45 ft | No |
Suburban Residential - Rural - Street frontage of 200 ft is required as well as the lot width shown, and two side yards at the 30 ft minimum fall fifteen feet short of the 75 ft required for the pair.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Rural Residential - The figures shown are for a one-family house with no municipal sewer or water and slight or moderate development limitations. Where limitations are severe, the lot is sixty thousand square feet with either service, and the most restrictive group applies with neither.
- Street frontage of 100 ft is required as well as the lot width shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
One-Family Residential - Street frontage of 85 ft is required as well as the lot width shown, and two side yards at the 15 ft minimum fall ten feet short of the 40 ft required for the pair.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Waterfront Residential - Street frontage of 40 ft is required as well as the lot width shown, and the coverage figure is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Manufactured Housing Community - The table states the lot minimum twice, five thousand and eight thousand square feet, each against a footnoted condition, and the figure shown is the smaller.
- Street frontage of 50 ft is required as well as the lot width shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Senior Residential Community - The district has no floor area ratio, so 75% development coverage and a height of 35 ft or two storeys, whichever binds first, are the whole of its intensity control.
- Street frontage of 100 ft is required as well as the lot width shown.
- The coverage figure is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Public Waterfront - Street frontage of 100 ft is required as well as the lot width shown. The side and rear yard depth, which is what an accessory structure keeps, is 25 to 30 ft, well short of the 50 ft setbacks shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- A 75 ft building setback from the Palisades Interstate Park property line should be kept where feasible.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Business - The 15 ft front figure shown is the yard depth from the front lot line. The table also prints a 40 ft front setback, and where the buildings that define it exist, the larger of the two governs.
- Under § 215-5 a setback is the average setback established by three or more buildings of the same district within three hundred feet on each side of the lot, along the same side of the street.
- No side setback is required at all, on either side or for the two sides together.
- Street frontage of 50 ft is required as well as the lot width shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Office - The 20 ft front figure shown is the yard depth from the front lot line. The table also prints a 60 ft front setback, and where the buildings that define it exist, the larger of the two governs.
- Under § 215-5 a setback is the average setback established by three or more buildings of the same district within three hundred feet on each side of the lot, along the same side of the street.
- Street frontage of 150 ft is required as well as the lot width shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Light Industrial, Light Industrial 2, Route 9W Rural Business/Research - The 15 ft front figure shown is the yard depth from the front lot line. The table also prints a 75 ft front setback, and where the buildings that define it exist, the larger of the two governs.
- Under § 215-5 a setback is the average setback established by three or more buildings of the same district within three hundred feet on each side of the lot, along the same side of the street.
- Street frontage of 100 ft is required as well as the lot width shown.
- The coverage figure shown is a development coverage, not a cap on building footprint.
- An accessory structure keeps the required side and rear yard depth, which is smaller than the setbacks shown.
- Along any Palisades Interstate Park or Parkway property, a 20 ft buffer is required, with a further 10 ft planted in evergreens unless the topography already hides the site from the Parkway.
- All parking must stand at least 10 ft back from the designated street line of a county or state highway, and a residential lot taking access from one must provide a turnaround.
Size limits on record in Stony Point
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 Stony Point:
- Suburban Residential - RuralA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Rural ResidentialA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- One-Family ResidentialA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Waterfront ResidentialA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Public WaterfrontA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- BusinessA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- OfficeA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Light IndustrialA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Light Industrial 2A freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
- Route 9W Rural Business/ResearchA freestanding unit needs at least two acres. A unit inside the principal house needs a lot meeting the district's required area and a primary dwelling of 3,000 square feet or more of living area.
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 Orange & Rockland 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 rentalsShort-term rentals prohibited. Stony Point bars rentals of less than 29 days in its residential districts, and transient rental of a dwelling unit is not a listed permitted use in any district under Chapter 215. Separate question from whether you can build the unit.
- Zoning codeecode360.com/11119275
- Building dept(845) 786-2716
Sizing up a specific parcel in Stony Point?
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Building a full house instead?
A standard-finish house in Stony Point runs $229–300/sq ft, about $410k–540k at 1,800 sq ft , plus roughly $9,891 for a conforming lot. See what it costs to build a house in Stony Point.
ADU cost in nearby towns
All Rockland County towns: Clarkstown · Haverstraw · Orangetown · Ramapo · Airmont (Village) · Chestnut Ridge (Village) · Grand View-on-Hudson (Village) · Haverstraw (Village) · Hillburn (Village) · Montebello (Village) · New Hempstead (Village) · Nyack (Village) · Piermont (Village) · Pomona (Village) · Sloatsburg (Village) · Spring Valley (Village) · Suffern (Village) · Upper Nyack (Village) · Wesley Hills (Village) · West Haverstraw (Village)
More on Stony Point: Can you build an ADU here? · Zoning for new construction · Rockland County build cost
ADU cost in Stony Point: common questions
How much does it cost to build an ADU in Stony Point, NY?
An 800 sq ft accessory dwelling unit in Town of Stony Point runs roughly $225k–295k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $150k–195k. 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 Stony Point?
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 $280–366/sq ft against $229–300/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Stony Point?
Town of Stony Point has 12 districts. 9 districts prohibit ADUs, 3 require a special-use permit. Check the specific address with the free ADU checker or confirm with the building department at (845) 786-2716 before you spend money on design.
Can I rent an ADU in Stony Point short term?
Short-term rentals prohibited for Town of Stony Point. 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 Rockland 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 Town of Stony Point vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-07-21; verify with the building department at (845) 786-2716 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.