Lumberland · ADU cost
What it costs to build an ADU in Lumberland, NY
An 800 sq ft accessory dwelling unit in Lumberland 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 Lumberland maps 7 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 Lumberland
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 Lumberland 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 |
|---|---|---|---|---|
| River Hamlet District | 3 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
| Rural Residential District | 5 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
| Hillside District | 5 ac | 50 / 50 / 50 ft | 35 ft | Occupancy restricted |
| Glen Spey District | 3 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
| Mohican Lake District | 2 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
| Mongaup River Valley District | 5 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
| Black Forest District | 5 ac | 50 / 35 / 50 ft | 35 ft | Occupancy restricted |
River Hamlet District - A lot here needs 3 acres and 150 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 35 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 30% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- The side yard follows lot size: 25 feet on a lot of 1 acre or smaller, 30 feet above 1 acre but below 3 acres, and 35 feet on 3 acres or larger.
- Coverage follows lot size too: 75% at 1 acre or less, 65% at 1.1 to 1.5, 55% at 1.6 to 2, 40% at 2.1 to 2.5, 30% at 2.6 to 3 and 20% above 3 acres.
- Lot clearing carries its own tier: 90% at 1 acre or less, 80% at 1.1 to 1.5, 70% at 1.6 to 2, 60% at 2.1 to 2.5, 50% at 2.6 to 3 and 40% above 3 acres.
- Development is not allowed on slopes steeper than 15%.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Rural Residential District - A lot here needs 5 acres and 200 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 35 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 15% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- The side yard follows lot size: 25 feet on a lot smaller than 3 acres, 35 feet on a lot of 3 to 9 acres and 75 feet on a lot larger than 9 acres.
- A separate cap holds lot clearing to 30% of the lot, above the 15% that building and other hard surface may cover.
- Development is not allowed on slopes steeper than 15%.
- Multifamily dwelling units need a special use permit, with 5 acres for the first two units and two and one half acres for each unit after that.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Hillside District - A lot here needs 5 acres and 200 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 50 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 15% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- A separate cap holds lot clearing to 30% of the lot, above the 15% that building and other hard surface may cover.
- Development is not allowed on slopes steeper than 15%.
- A conservation subdivision is preferred here, and the Planning Board sets the individual lot sizes and the yard requirements at plat approval.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Glen Spey District - A lot here needs 3 acres and 150 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 35 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 30% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- The side yard follows lot size: 25 feet on a lot smaller than 3 acres, 35 feet on a lot of 3 to 9 acres and 75 feet on a lot larger than 9 acres.
- Coverage follows lot size too: 75% at 1 acre or less, 65% at 1.1 to 1.5, 55% at 1.6 to 2, 40% at 2.1 to 2.5, 30% at 2.6 to 3 and 20% above 3 acres.
- Lot clearing carries its own tier: 90% at 1 acre or less, 80% at 1.1 to 1.5, 70% at 1.6 to 2, 60% at 2.1 to 2.5, 50% at 2.6 to 3 and 40% above 3 acres.
- A manufactured home park needs a special use permit and a site of at least 20 acres, with 100 feet of frontage on a public road and a 75-foot setback from it.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Mohican Lake District - A lot here needs 2 acres and 150 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 35 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 20% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- A separate cap holds lot clearing to 50% of the lot, above the 20% that building and other hard surface may cover.
- Development is not allowed on slopes steeper than 15%.
- A conservation subdivision needs a special use permit at the same 2 acres and 150 feet of width, and the Planning Board sets the lot sizes and yards at plat approval.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Mongaup River Valley District, Black Forest District - A lot here needs 5 acres and 200 feet of width. A building sits 50 feet back from the edge of the road right-of-way, 35 feet from each side and 50 feet from the rear, reaches 35 feet, and building plus other hard surface may cover 20% of the lot.
- Where the road has no right-of-way the front yard is measured 75 feet from the center of the road, not from the front lot line.
- The side yard follows lot size: 25 feet on a lot smaller than 3 acres, 35 feet on a lot of 3 to 9 acres and 75 feet on a lot larger than 9 acres.
- Coverage follows lot size too: 75% at 1 acre or less, 65% at 1.1 to 1.5, 55% at 1.6 to 2, 40% at 2.1 to 2.5, 30% at 2.6 to 3 and 20% above 3 acres.
- Lot clearing carries its own tier: 90% at 1 acre or less, 80% at 1.1 to 1.5, 70% at 1.6 to 2, 60% at 2.1 to 2.5, 50% at 2.6 to 3 and 40% above 3 acres.
- Development is not allowed on slopes steeper than 15%.
- A dwelling needs at least 720 square feet of habitable floor area, and 500 square feet for an accessory apartment or care cottage over the garage.
Size limits on record in Lumberland
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 Lumberland:
- River Hamlet DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Rural Residential DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Hillside DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Glen Spey DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Mohican Lake DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Mongaup River Valley DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
- Black Forest DistrictThe apartment needs at least seven hundred twenty square feet of habitable floor area if it stands apart from the house and any garage, or five hundred square feet if over or attached to a garage.
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 Town of Lumberland 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 codeecode360.com/LU3128
- Building dept(845) 856-8600
Sizing up a specific parcel in Lumberland?
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Building a full house instead?
A standard-finish house in Lumberland runs $195–256/sq ft, about $350k–460k at 1,800 sq ft , plus roughly $50,724 for a conforming lot. See what it costs to build a house in Lumberland.
ADU cost in nearby towns
All Sullivan County towns: Bethel · Callicoon · Cochecton · Delaware · Fallsburg · Forestburgh · Fremont · Highland · Liberty · Mamakating · Neversink · Rockland · Thompson · Tusten · Bloomingburg (Village) · Jeffersonville (Village) · Liberty (Village) · Monticello (Village) · Woodridge (Village)
More on Lumberland: Can you build an ADU here? · Zoning for new construction · Sullivan County build cost
ADU cost in Lumberland: common questions
How much does it cost to build an ADU in Lumberland, NY?
An 800 sq ft accessory dwelling unit in Town of Lumberland 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 Lumberland?
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 Lumberland?
Town of Lumberland has 7 districts. All districts allow ADUs with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (845) 856-8600 before you spend money on design.
Can I rent an ADU in Lumberland short term?
No local short-term-rental law on record - which is not the same as permission for Town of Lumberland. 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 Lumberland 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) 856-8600 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.