New Windsor · ADU cost
What it costs to build an ADU in New Windsor, NY
An 800 sq ft accessory dwelling unit in New Windsor runs roughly $205k–270k, or about $258–337/sq ft, and that per-square-foot figure sits deliberately above the $211–276/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 New Windsor maps 14 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 New Windsor
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Orange County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $342–$447 | $135k–180k |
| 600 sq ft | One bedroom | $286–$374 | $170k–225k |
| 800 sq ft | One bedroom, larger | $258–$337 | $205k–270k |
| 1,000 sq ft | Two bedroom | $241–$315 | $240k–315k |
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–$11 | $8 | — |
| Foundation | $17–$24 | $17 | — |
| Framing | $26–$33 | $26 | — |
| Envelope - roof, siding, windows | $33–$42 | $33 | — |
| Plumbing | $29–$35 | $17 | 55% |
| Electrical | $19–$24 | $13 | 35% |
| HVAC | $24–$29 | $15 | 45% |
| Insulation | $8–$9 | $8 | — |
| Interior finishes | $33–$45 | $28 | 15% |
| Millwork & cabinetry | $19–$29 | $11 | 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 New Windsor 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 |
|---|---|---|---|---|
| Rural Residential | 1.38 ac | 45 / 40 / 50 ft | 35 ft | No |
| Open Space Residential | 0.92 ac | 40 / 30 / 40 ft | 35 ft | No |
| Suburban Residential | 0.92 ac | 40 / 30 / 40 ft | 35 ft | No |
| Suburban Residential | 0.92 ac | 40 / 30 / 40 ft | 35 ft | No |
| Multiple-Family Residential | 0.92 ac | 40 / 30 / 40 ft | 35 ft | No |
| Clustered Open Space — Butterhill | 0.29 ac | 40 / 12 / 40 ft | 35 ft | No |
| Clustered Open Space — Meadowbrook | 0.57 ac | 30 / 10 / 40 ft | 35 ft | No |
| Clustered Open Space — Woodlawn Manor | 0.46 ac | 40 / 12 / 40 ft | 35 ft | No |
| Airport | 3 ac | 100 / 50 / 50 ft | 40 ft | No |
| Highway Commercial | 0.92 ac | 60 / 30 / 30 ft | — | No |
| Limited Commercial | 0.92 ac | 60 / 30 / 30 ft | — | No |
| Neighborhood Commercial | 0.23 ac | 40 / 15 / 15 ft | 35 ft | No |
| Office and Light Industry | 0.23 ac | 40 / 15 / 15 ft | 35 ft | No |
| Planned Industrial | 0.92 ac | 50 / 15 / 20 ft | — | No |
Rural Residential - Beside the gross lot area shown, a lot must also hold at least forty thousand square feet net, so wetland or steep ground can make a lot with enough gross area fail. Public water and sewer do not change the lot size here.
- The minimum lot width of 150 ft falls to a hundred and twenty-five feet where more than half the road frontage is on a cul-de-sac
- A street frontage of at least seventy feet applies too, as a standard separate from lot width
- Crops, vineyards, orchards and nurseries, mining, and boarding or breeding cattle, sheep, goats, pigs or more than two horses each need a lot of at least twenty acres
- Cemeteries need at least ten acres, fowl and commercial forestry five, and indoor and outdoor recreation and places of worship three
- Every use except a one-family dwelling needs Planning Board site plan approval
Open Space Residential - The figures shown assume public water and public sewer. Without both, the lot must be at least sixty thousand square feet, with yards of at least 45 ft front, 40 ft on each side and 80 ft combined, and 50 ft rear.
- The lot must meet a net area figure as well as the gross one, so wetland or steep ground can make a lot with enough gross area fail
- The minimum lot width of 150 ft falls to a hundred and twenty-five feet where more than half the road frontage is on a cul-de-sac
- A street frontage of at least seventy feet applies too, as a standard separate from lot width
- Other uses need larger lots: at least twenty acres for cattle, sheep, goats, pigs or more than two horses; ten for commercial dog or veterinary kennels; five for fowl or commercial forestry
- Indoor and outdoor recreation and places of worship need at least three acres
- Every use except a one-family dwelling needs Planning Board site plan approval
Suburban Residential - The figures shown are for a one-family house on public water and sewer; without both it needs at least sixty thousand square feet and deeper yards. A two-family house is permitted by right on at least sixty thousand square feet with services, or at least eighty thousand without.
- A two-family lot must be at least a hundred and seventy-five feet wide, with yards of at least fifty feet front and fifty on each side, and at least a hundred for the pair
- Each unit of a two-family house needs at least 1,500 sq ft of livable floor area
- The lot must meet a net area figure as well as the gross one, so wetland or steep ground can make a lot with enough gross area fail
- The minimum lot width of 150 ft falls to a hundred and twenty-five feet where more than half the road frontage is on a cul-de-sac
- A street frontage of at least seventy feet applies too, as a standard separate from lot width
- Every use except a one-family dwelling needs Planning Board site plan approval
Suburban Residential - Only a one-family dwelling is permitted by right here. The lot size shown holds whether or not public water and sewer are available.
- The lot must meet a net area figure as well as the gross one, so wetland or steep ground can make a lot with enough gross area fail
- The minimum lot width of 150 ft falls to a hundred and twenty-five feet where more than half the road frontage is on a cul-de-sac
- A street frontage of at least seventy feet applies too, as a standard separate from lot width
- Other uses need larger lots: at least ten acres for cemeteries and mausoleums, five for crops, vineyards, orchards, nurseries or commercial forestry, three for recreation or places of worship
- Every use except a one-family dwelling needs Planning Board site plan approval
Multiple-Family Residential - The figures shown are for a one-family house. A multiple dwelling of three or more families needs at least five acres on both central water and central sewer, at no more than seven units to the net acre.
- A multiple dwelling needs at least twenty feet of lot width and fifteen feet of street frontage, a front yard of at least thirty feet and a rear yard of at least a hundred, with coverage up to 50%
- A multiple dwelling needs no side yard, but if one is provided the pair must total at least thirty-five feet
- Multiple-dwelling units need at least seven hundred square feet of floor area for a one-bedroom unit, eight hundred for a two-bedroom and a thousand for a three-bedroom
- A two-family house on public water and sewer needs at least sixty thousand square feet, with side yards of at least forty feet each and eighty for the pair
- The lot must meet a net area figure as well as the gross one, so wetland or steep ground can make a lot with enough gross area fail
- Every use except a one-family dwelling needs Planning Board site plan approval
Clustered Open Space — Butterhill - This is a cluster district tied to one named subdivision, the Butterhill project, and only one-family dwellings are permitted here, one to a lot.
- A street frontage of at least sixty feet applies too, as a standard separate from lot width
Clustered Open Space — Meadowbrook - The lot figures shown are conditioned on both municipal water and municipal sewer. Only one-family dwellings are permitted here, one to a lot.
- This is a cluster district tied to one named subdivision, the Meadowbrook Major Subdivision
- A street frontage of at least seventy feet applies too, as a standard separate from lot width
Clustered Open Space — Woodlawn Manor - At least twelve thousand five hundred square feet of the lot must be buildable land, and both that and the gross lot area shown must be met. The figures are conditioned on both municipal water and municipal sewer.
- Only one-family dwellings are permitted here, one to a lot
- This is a cluster district tied to one named subdivision, the Woodlawn Manor Subdivision
- A street frontage of at least sixty feet applies too, as a standard separate from lot width
Airport - The figures shown are for indoor and outdoor recreation. Offices and office-warehouse businesses need at least forty thousand square feet on at least a hundred feet of width, and their height is set by distance to the nearest lot line rather than a fixed figure.
- Offices and office-warehouses need yards of at least thirty feet front, twenty on each side with forty for the pair, and thirty rear, and are held to a floor area ratio of a fifth
- An office or office-warehouse building may rise twelve inches for every foot of distance to the nearest lot line
- The 40 ft height limit applies to recreation uses only
- A street frontage of at least fifty feet applies too, as a standard separate from lot width
- Every use here needs Planning Board site plan approval
Highway Commercial - Height is set by distance rather than a fixed figure: a building may rise twelve inches for every foot of distance to its nearest lot line, so one set fifty feet back may rise fifty feet.
- With 30 ft on each side and 70 ft for the pair, one side yard must be at least forty feet
- The only dwelling permitted is living quarters for one family inside a commercial building, for the owner or caretaker of the use, by Planning Board special use permit
- Retail stores, banks and service establishments are the principal permitted uses; gasoline stations need a special use permit
- Every use here needs Planning Board site plan approval
Limited Commercial - Height is set by distance rather than a fixed figure: a building may rise twelve inches for every foot of distance to its nearest lot line, so one set fifty feet back may rise fifty feet.
- With 30 ft on each side and 70 ft for the pair, one side yard must be at least forty feet
- The only dwelling permitted is living quarters for one family inside a commercial building, for the owner or caretaker of the use, by Planning Board special use permit
- Every use here needs Planning Board site plan approval
Neighborhood Commercial - The figures shown are for retail stores and banks. Indoor and outdoor recreation needs at least five acres and places of worship at least three.
- Recreation needs at least two hundred feet of width and fifty feet of street frontage, with yards of at least a hundred feet front, fifty on each side with a hundred for the pair, and fifty rear
- Recreation has a fifty-foot height limit
- Places of worship need at least a hundred and twenty-five feet of width and 70 ft of street frontage, with yards of at least 45 ft front, 20 ft on each side with 40 ft for the pair, and 50 ft rear
- With at least 15 ft on each side and 35 ft for the pair, one side yard must be at least twenty feet
- The only dwelling permitted is living quarters for one family inside a commercial building, for the owner or caretaker, by special use permit
- Every use here needs Planning Board site plan approval
Office and Light Industry - The figures shown are for offices. A business combining offices with a warehouse, distribution centre or research laboratory, or a product testing and research laboratory, needs at least eighty thousand square feet on at least two hundred feet of width.
- Those larger uses need yards of at least a hundred feet front, fifty on each side with a hundred for the pair, and fifty rear, and are held to a floor area ratio of a fifth
- Their height is set by distance: twelve inches of building for every foot of distance to the nearest lot line
- A temporary business or commercial trailer of not more than six months needs a special use permit and is held to 20% coverage
- Every use here needs Planning Board site plan approval
Planned Industrial - Height is set by distance rather than a fixed figure: a building may rise twelve inches for every foot of distance to its nearest lot line. Manufacturing and processing need a special use permit.
- With 15 ft on each side and 40 ft for the pair, one side yard must be at least twenty-five feet
- A single dwelling unit for the exclusive use of an attendant, watchman or caretaker employed in a permitted use on the lot needs a special use permit, and coverage there is cut to 60%
- A temporary business or commercial trailer of not more than six months needs a special use permit, and coverage there is cut to 60%
- Every use here needs Planning Board site plan approval
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 Central Hudson 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. New Windsor has no local short-term rental law as of June 2026. That is not the same as permission, so confirm with the Town building department before counting on the use. Separate question from whether you can build the unit.
- Zoning codeecode360.com/6192891
- Building dept(845) 563-4615
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Building a full house instead?
A standard-finish house in New Windsor runs $211–276/sq ft, about $380k–495k at 1,800 sq ft , plus roughly $28,173 for a conforming lot. See what it costs to build a house in New Windsor.
ADU cost in nearby towns
All Orange County towns: Middletown (City) · Newburgh (City) · Port Jervis (City) · Blooming Grove · Chester · Cornwall · Crawford · Deerpark · Goshen · Greenville · Hamptonburgh · Highlands · Minisink · Monroe · Montgomery · Mount Hope · Newburgh · Palm Tree · Tuxedo · Wallkill · Warwick · Wawayanda · Chester (Village) · Cornwall-on-Hudson (Village) · Florida (Village) · Goshen (Village) · Greenwood Lake (Village) · Harriman (Village) · Highland Falls (Village) · Kiryas Joel (Village) · Maybrook (Village) · Monroe (Village) · Montgomery (Village) · Otisville (Village) · South Blooming Grove (Village) · Tuxedo Park (Village) · Walden (Village) · Warwick (Village) · Washingtonville (Village) · Woodbury (Village)
More on New Windsor: Can you build an ADU here? · Zoning for new construction · Orange County build cost
ADU cost in New Windsor: common questions
How much does it cost to build an ADU in New Windsor, NY?
An 800 sq ft accessory dwelling unit in Town of New Windsor runs roughly $205k–270k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $135k–180k. 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 New Windsor?
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 $258–337/sq ft against $211–276/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in New Windsor?
Town of New Windsor has 14 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (845) 563-4615 before you spend money on design.
Can I rent an ADU in New Windsor short term?
No local short-term-rental law on record - which is not the same as permission for Town of New Windsor. 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 Orange 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 New Windsor vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-09-15; verify with the building department at (845) 563-4615 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.