Highlands · ADU cost
What it costs to build an ADU in Highlands, NY
An 800 sq ft accessory dwelling unit in Highlands 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 Highlands maps 9 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 Highlands
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 Highlands 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 |
|---|---|---|---|---|
| Mountain Residence | 0.92 ac | 45 / 20 / 45 ft | 35 ft | No |
| Single-Family Residence | 0.46 ac | 45 / 20 / 45 ft | 35 ft | No |
| Single-Family Residence | 0.17 ac | 30 / 10 / 30 ft | 35 ft | No |
| Single- and Two-Family Residence | 0.13 ac | 20 / 10 / 25 ft | 35 ft | No |
| Apartment Residence | 0.11 ac | 20 / 10 / 25 ft | 35 ft | No |
| Apartment-Motel Residence | 0.11 ac | 20 / 10 / 25 ft | 35 ft | No |
| Mobile Home Court | 3.44 ac | 50 / 25 / 25 ft | 35 ft | No |
| Riverside Residence | 0.92 ac | 45 / 20 / 45 ft | 35 ft | No |
| Business | 0.34 ac | 30 / 20 / 30 ft | 35 ft | No |
Mountain Residence - The lot minimum and coverage shown hold only on ground under eleven percent natural grade. Between eleven and twenty percent a lot needs at least sixty thousand square feet at twenty percent coverage, and over twenty percent at least eighty thousand at fifteen percent.
- A two-family house, permitted by right here, needs at least eighty thousand square feet unsewered, because each dwelling unit needs forty thousand.
- Coverage counts main and accessory buildings together.
- At least fifty feet of street frontage at the street line is required, separate from the lot width.
- A side yard on the street side of a corner lot must be at least forty-five feet.
- Without public sewer a lot may not be built on unless it has room for a private waste disposal system the municipality accepts.
- The enclosed first floor of a dwelling must be at least seven hundred and fifty square feet with no dimension under twenty feet, not counting porches, breezeways, garages, basements or cellars.
Single-Family Residence - A two-family house and a multiple dwelling are prohibited here. A planned residential development, by special exception and site plan approval, is the one route to different figures.
- In a planned residential development the Planning Board may modify lot area, lot width, yards, setbacks and street frontage, but not height, at no more than 2.4 dwelling units to the gross acre.
- Units in a planned residential development may be single-family, two-family or multiple-dwelling structures.
- Coverage counts main and accessory buildings together.
- At least fifty feet of street frontage at the street line is required, separate from the lot width.
- A side yard on the street side of a corner lot must be at least forty-five feet.
- Without public sewer a lot may not be built on unless it has room for a private waste disposal system the municipality accepts.
Single-Family Residence - A two-family house, a multiple dwelling and the conversion of an existing house for two families are all prohibited here. A planned residential development, by special exception and site plan approval, is the one route to different figures.
- In a planned residential development the Planning Board may modify lot area, lot width, yards, setbacks and street frontage, but not height, at no more than 5.7 dwelling units to the gross acre.
- Units in a planned residential development may be single-family, two-family or multiple-dwelling structures.
- Coverage counts main and accessory buildings together.
- At least fifty feet of street frontage at the street line is required, separate from the lot width.
- A side yard on the street side of a corner lot must be at least thirty feet.
- Without public sewer a lot may not be built on unless it has room for a private waste disposal system the municipality accepts.
Single- and Two-Family Residence - A one-family house, a two-family house and the conversion of an existing house for two families are all permitted; a multiple dwelling is not. The lot area and coverage hold at every natural grade.
- By special exception and site plan approval, a planned residential development may modify lot area, width, yards, setbacks and frontage, but not height, up to 8 dwelling units to the gross acre.
- In a planned residential development of an acre or more, a multiple-dwelling building may reach seventy feet if the Planning Board finds water, fire equipment and street access adequate.
- Such a building must stand back from every property line at least a third of the height of the wall facing it.
- The side yards together must be at least eighteen feet, so a house at least ten feet from one line may sit as close as eight feet to the other.
- Coverage counts main and accessory buildings together.
- At least fifty feet of street frontage at the street line is required, separate from the lot width.
Apartment Residence - The figures shown are for a one-family house; a two-family house is also permitted by right and fits the minimum lot exactly. An apartment building is a special exception use with its own land requirement.
- Each townhouse unit needs at least five thousand four hundred and forty-five square feet of land and takes no side yard; each apartment unit needs at least three thousand six hundred and thirty.
- A multiple-dwelling building on an acre or more may reach forty-five feet, only under the special exception and only if the Planning Board finds water, fire equipment and street access adequate.
- Such a building must stand back from every property line at least a third of the height of the wall facing it.
- Apartment buildings must be at least thirty-five feet apart, or two-thirds the height of the taller if that is greater.
- By special exception and site plan approval, a planned residential development may modify lot area, width, yards, setbacks and frontage, but not height, up to 10 dwelling units to the gross acre.
- Coverage counts main and accessory buildings together.
Apartment-Motel Residence - A two-family house is the use permitted by right here; a one-family house and an apartment building each need a special exception. A two-family house fits the minimum lot exactly, and a four-unit building needs ten thousand square feet.
- A multiple-dwelling building on an acre or more may reach forty-five feet, only under the special exception and only if the Planning Board finds water, fire equipment and street access adequate.
- Such a building must stand back from every property line at least a third of the height of the wall facing it.
- Apartment buildings must be at least thirty-five feet apart, or two-thirds the height of the taller if that is greater.
- By special exception and site plan approval, a planned residential development may modify lot area, width, yards, setbacks and frontage, but not height, up to 10 dwelling units to the gross acre.
- Coverage counts main and accessory buildings together.
- A side yard on the street side of a corner lot must be at least twenty feet.
Mobile Home Court - Every use in this district, the mobile home court, the single-family house and the two-family house alike, needs a special exception. The special exception standard for a licensed court requires a site of not less than five acres.
- Each mobile home space takes four thousand square feet and must be at least forty feet wide and a hundred feet long.
- A mobile home in a licensed court needs five hundred square feet of floor area per family; one outside a licensed court needs nine hundred.
- Initial development must cover at least two acres and each later addition at least one.
- Interior roadways are twenty feet wide with curbs or gutters, and there must be two access drives to the public street.
- Recreation land runs one acre for every hundred spaces and never less than half an acre.
- A planned residential development is not available in this district.
Riverside Residence - The lot minimum counts usable land only: slopes of twenty-five to thirty-five percent count at half their area, and slopes over thirty-five percent, wetlands and special flood hazard land at a quarter. No principal building may stand on ground sloping twenty percent or more.
- Even a one-family house needs site plan review and approval, and buildings must be sited to preserve as much existing vegetation as possible.
- The two-family house permitted here needs at least eighty thousand square feet of usable land unsewered.
- Coverage counts main and accessory buildings together.
- In a planned residential development, by special exception, the unit count is what the schedule allows, but the whole parcel counts, steep slopes, wetlands and flood hazard land included.
- In such a development no unit may be built in a wetland or special flood hazard area, multiple dwellings must stand at least twenty feet apart, and the applicant pays into the parkland trust fund.
- A side yard on the street side of a corner lot must be at least forty-five feet.
Business - A house and a ground-floor dwelling are prohibited here; the only dwelling allowed is one above a first-floor nonresidential use, and it needs a special exception.
- Along a boundary with a residence district a transitional yard of at least twenty feet is required, screened with a six-foot stockade fence or its equal kept up by the business owner.
- A side yard on the street side of a corner lot must be at least twenty feet.
- Coverage counts main and accessory buildings together.
- Off-street parking may fill a required front, side or rear yard entirely.
- Every building permit except one for a one-family or two-family residence needs site plan approval from the Planning Board.
- No minimum street frontage applies in this district.
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 rentalsShort-term rentals allowed with local rules. Short-term rentals in the Town of Highlands need a permit, with a $500 annual fee and an inspection. They are allowed in residential districts where single-family dwellings are permitted. Separate question from whether you can build the unit.
- Zoning codeecode360.com/12022709
- Building dept(845) 446-4280
Sizing up a specific parcel in Highlands?
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Building a full house instead?
A standard-finish house in Highlands runs $211–276/sq ft, about $380k–495k at 1,800 sq ft , plus roughly $5,701 for a conforming lot. See what it costs to build a house in Highlands.
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 · Minisink · Monroe · Montgomery · Mount Hope · New Windsor · 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 Highlands: Can you build an ADU here? · Zoning for new construction · Orange County build cost
ADU cost in Highlands: common questions
How much does it cost to build an ADU in Highlands, NY?
An 800 sq ft accessory dwelling unit in Town of Highlands 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 Highlands?
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 Highlands?
Town of Highlands has 9 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (845) 446-4280 before you spend money on design.
Can I rent an ADU in Highlands short term?
Short-term rentals allowed with local rules for Town of Highlands. 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 Highlands 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) 446-4280 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.