Fallsburg · ADU cost
What it costs to build an ADU in Fallsburg, NY
An 800 sq ft accessory dwelling unit in Fallsburg 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 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 Fallsburg maps 7 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
Check a specific parcel for an ADU in Aldo, free →
ADU cost by size in Fallsburg
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 Fallsburg 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 |
|---|---|---|---|---|
| Agricultural District | 10 ac | 50 / 50 / 50 ft | 35 ft | No |
| Low-Density Residential/Recreation District | 3 ac | 75 / 40 / 50 ft | 35 ft | No |
| Residence District | 0.5 ac | 35 / 20 / 25 ft | 35 ft | No |
| Hamlet Residence District | 0.29 ac | 35 / 10 / 25 ft | 35 ft | No |
| Business District | 0.23 ac | 35 / 10 / 25 ft | 35 ft | No |
| Mixed Use District | 0.29 ac | 35 / 10 / 25 ft | 35 ft | No |
| Planned Resort Development District | 0.75 ac | 150 / 25 / 25 ft | 35 ft | No |
Agricultural District - A one-family house sits on 10 acres with 350 feet of lot width, 50 feet to the front, rear and each side line, 100 feet for both sides together, 10% lot coverage, 1,200 square feet of floor area and 35 feet of height.
- Farm worker housing, two units per farm, moves the front setback to 75 feet and the floor area to 750 square feet on the same 10 acre lot.
- Hunting and fishing cabins take a 100 foot front setback, 75 feet to the rear and each side, 150 feet for both sides and 800 square feet of floor area.
- Class 2 agricultural operations, commercial forestry and concentrated animal feeding operations take 500 feet of width, 100 feet to the rear and sides and 200 feet for both.
- Wildlife and game preserves take 25 acres and 750 feet of width, hog raising takes 50 acres, and a home occupation takes 0.5 acre.
- Kennels need a special permit, 25 acres, 1,000 feet of width, 500 foot setbacks and 20% coverage, and quarry operations a 200 foot front setback.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Low-Density Residential/Recreation District - A one-family house without public sewer sits on 3 acres with 200 feet of lot width, 75 feet to the front, 50 feet to the rear, 40 feet to one side and 80 feet for both, 10% lot coverage, 1,200 square feet of floor area and 35 feet of height.
- On public sewer the same house needs 2 acres.
- A manufactured home park without public water and sewer takes 10 acres, 750 feet of width, 50 feet to each side, 100 feet for both, 20% coverage and 980 square feet of floor area.
- Vacation campgrounds and retreats need a special permit on 25 acres with a 200 foot front setback, 150 feet to the rear and sides and 300 feet for both.
- Hotels and resort hotels need a special permit on 10 acres with 500 feet of width, 100 foot setbacks, 20% coverage and 250 square feet per room.
- An accessory structure is held to 25 feet of height.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Residence District - A one-family house on public sewer and water sits on 0.5 acre with 100 feet of lot width, 35 feet to the front, 25 feet to the rear, 20 feet to one side and 40 feet for both, 20% lot coverage, 1,200 square feet of floor area and 35 feet of height.
- Without public sewer and water the same house needs 3 acres, 200 feet of width, 50 feet to the front and rear, 40 feet to one side, 80 feet for both and 10% coverage.
- A townhouse development needs a special permit, 10 acres, 500 feet of width, 150 feet to the front, 50 feet to the rear and each side, 100 feet for both and 30% coverage.
- Each townhouse unit counts on 14,500 square feet of land, floor areas run 1,100 square feet for three bedrooms, 950 for two and 800 for one, and 7 units may share a building.
- A duplex development needs a special permit and a site of at least 10 acres under § 310-5.30.
- In a duplex development the front yard is 150 feet from an external public right of way, side and rear yards are 50 feet, and 25% caps everything built or paved.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Hamlet Residence District - A one-family house on public sewer and water sits on 0.287 acre, 12,500 square feet, with 100 feet of lot width, 35 feet to the front, 25 feet to the rear, 10 feet to one side and 30 feet for both, 25% coverage, 1,200 square feet of floor area and 35 feet of height.
- A two-family house takes 0.5739 acre, 25,000 square feet, 125 feet of width, 20 feet to one side, 50 feet for both and 1,500 square feet of floor area.
- Multifamily of three or four units takes 0.8609 acre, 37,500 square feet, 150 feet of width, 25 feet to one side, 50 feet for both and 800 square feet of floor area.
- Multifamily of more than four units takes 1.1478 acre, 50,000 square feet, and 200 feet of width under § 310-5.14.
- A townhouse development needs a special permit, 5 acres, 350 feet of width, 50 feet to the front, rear and each side, 100 feet for both, 30% coverage and 12,500 square feet per unit.
- A duplex development needs a special permit, at least 10 acres and 25% on everything built or paved under § 310-5.30.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Business District - The commercial rows of this district sit on 0.2296 acre, 10,000 square feet, with no required width, 35 feet to the front, 25 feet to the rear, 10 feet to one side, 20 feet for both, 75% coverage and 35 feet of height.
- A dwelling over a store carries no lot area, width or setback of its own, only a minimum floor area of 800 square feet and the 35 foot height.
- A retail store and agribusiness are held to 70% coverage, public utilities to 50%, and a house of worship, a religious use or a home occupation to 25%.
- A home occupation sits on 0.5 acre, and public parks and playgrounds on 3 acres with 200 feet of width, a 75 foot front setback and 10% coverage.
- Hotels and elementary, secondary and religious schools need a special permit on 5 acres with 350 feet of width, 100 foot setbacks and 200 feet for both sides.
- A self-storage facility needs a special permit with a 200 foot front setback and 100 feet to the rear and sides.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Mixed Use District - A one-family house on public sewer and water sits on 0.287 acre, 12,500 square feet, with 100 feet of lot width, 35 feet to the front, 25 feet to the rear, 10 feet to one side and 30 feet for both, 25% coverage, 1,200 square feet of floor area and 35 feet of height.
- A commercial use here requires no lot area at all, 0 acres, and no lot width, 0 ft, with no front or side setback, only 10 feet to the rear and 80% coverage.
- Every existing vacant parcel in this district is buildable, and no residential use may occupy the first floor of a mixed-use building.
- A townhouse development needs a special permit, with 5 feet to the front, 10 feet to the rear and each side, 20 feet for both sides and 80% coverage.
- An artist gallery, studio or live and work unit takes 850 square feet of floor area, and a dwelling over a store takes 1,000 square feet.
- A home occupation is the one row with a lot minimum, 0.5 acre, and public parks and playgrounds sit at 50% coverage.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Planned Resort Development District - A one-family house sits on 0.75 acre with 125 feet of lot width, 150 feet to the front, 25 feet to the rear and to each side, 50 feet for both sides, 1,200 square feet of floor area and 35 feet of height.
- A two-family house needs 1.5 acres.
- A townhouse development needs a special permit, 10 acres, 300 feet of width, 50 feet to the rear and each side and 100 feet for both.
- Hotels and resort hotels need a special permit on 10 acres with 500 feet of width, a 200 foot front setback, 150 feet to the rear and sides, 300 feet for both and 45 feet of height.
- A golf course sits on 50 acres with 750 feet of width and 100 foot setbacks.
- Retail, restaurants, professional offices and personal service establishments accessory to a hotel sit on 1 acre with 125 feet of width and a 50 foot front setback.
- A site that also lies in the Neversink River Overlay is held to 10% coverage with a 100 foot undisturbed buffer along the river shoreline under § 310-29.1.
Size limits on record in Fallsburg
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 Fallsburg:
- Agricultural DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Low-Density Residential/Recreation DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Residence DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Hamlet Residence DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Business DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Mixed Use DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
- Planned Resort Development DistrictTwo-family dwellings are a permitted use in HR on 25,000 square feet and in PRD on 1.5 acres.
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 rentalsShort-term rentals allowed with local rules. Renting a home for fewer than 30 days is allowed in Fallsburg with an annual permit and a safety inspection from code enforcement. Separate question from whether you can build the unit.
- Zoning codeecode360.com/FA1866
- Building dept(845) 434-8811
Sizing up a specific parcel in Fallsburg?
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 Fallsburg runs $195–256/sq ft, about $350k–460k at 1,800 sq ft , plus roughly $2,887 for a conforming lot. See what it costs to build a house in Fallsburg.
ADU cost in nearby towns
All Sullivan County towns: Bethel · Callicoon · Cochecton · Delaware · Forestburgh · Fremont · Highland · Liberty · Lumberland · Mamakating · Neversink · Rockland · Thompson · Tusten · Bloomingburg (Village) · Jeffersonville (Village) · Liberty (Village) · Monticello (Village) · Woodridge (Village)
More on Fallsburg: Can you build an ADU here? · Zoning for new construction · Sullivan County build cost
ADU cost in Fallsburg: common questions
How much does it cost to build an ADU in Fallsburg, NY?
An 800 sq ft accessory dwelling unit in Town of Fallsburg 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 Fallsburg?
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 Fallsburg?
Town of Fallsburg has 7 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (845) 434-8811 before you spend money on design.
Can I rent an ADU in Fallsburg short term?
Short-term rentals allowed with local rules for Town of Fallsburg. 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 Town of Fallsburg 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) 434-8811 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.