Altamont · ADU cost
What it costs to build an ADU in Altamont, NY
An 800 sq ft accessory dwelling unit in Altamont runs roughly $195k–260k, or about $247–323/sq ft, and that per-square-foot figure sits deliberately above the $202–265/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 village 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 Village of Altamont maps 13 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 Altamont
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Albany County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $327–$428 | $130k–170k |
| 600 sq ft | One bedroom | $273–$358 | $165k–215k |
| 800 sq ft | One bedroom, larger | $247–$323 | $195k–260k |
| 1,000 sq ft | Two bedroom | $231–$302 | $230k–300k |
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–$11 | $7 | — |
| Foundation | $16–$23 | $16 | — |
| Framing | $25–$32 | $25 | — |
| Envelope - roof, siding, windows | $32–$41 | $32 | — |
| Plumbing | $27–$33 | $16 | 55% |
| Electrical | $18–$23 | $13 | 35% |
| HVAC | $23–$28 | $14 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $32–$43 | $27 | 15% |
| Millwork & cabinetry | $18–$27 | $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 Altamont 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 |
|---|---|---|---|---|
| Business | 0.23 ac | 15 / 20 / 30 ft | 35 ft | Occupancy restricted |
| Central Business District | — | 0 / 0 / 50 ft | 35 ft | Occupancy restricted |
| Light Industrial | 0.23 ac | 40 / 12.5 / 20 ft | 35 ft | Occupancy restricted |
| Park | — | — | — | No |
| Planned Unit Development | — | — | — | — |
| Residential One Family - 10,000 Sq. | 0.23 ac | 20 / 10 / 30 ft | 35 ft | Occupancy restricted |
| Residential Multi-Family - 10,000 Sq. | 0.23 ac | 20 / 10 / 30 ft | 35 ft | No |
| Residential Professional Office | 0.23 ac | 20 / 10 / 30 ft | 35 ft | Special permit |
| Residential One Family - 15,000 Sq. | 0.34 ac | 20 / 15 / 30 ft | 35 ft | Special permit |
| Residential One Family - 20,000 Sq. | 0.46 ac | 25 / 15 / 30 ft | 35 ft | Special permit |
| Residential One Family - 40,000 Sq. | 0.92 ac | 35 / 25 / 50 ft | 35 ft | Special permit |
| Residential Conservation District | 0.92 ac | 35 / 25 / 50 ft | 35 ft | Special permit |
| Residential Senior Citizen | 0.23 ac | 20 / 10 / 30 ft | 35 ft | Occupancy restricted |
Business - The 15 ft front setback is a minimum, and there is a ceiling as well: a building may sit no farther back than 30 ft. At least 20% of the lot has to stay uncovered and pervious, separate from the building coverage cap.
- A two-family dwelling needs a lot of at least 0.344 acre.
- A building that combines business use with an apartment has a lot minimum of 0.115 acre.
Central Business District - The 5,000 square foot lot minimum applies to commercial and mixed use buildings only, and the district sets none for a residential building, so confirm a housing plan with the village before counting on one.
- The 25 ft lot width is a minimum, and a lot may be no more than 80 ft wide.
- The front setback is a range: a building is placed at the edge of the sidewalk, up to a maximum setback of 10 ft.
- Side yards are not required, since zero lot lines are permitted, but a side yard that is provided has to be 12.5 to 20 ft.
- An accessory building keeps 5 ft to a side lot line.
- The 50 ft rear yard is there to make room for parking behind the building.
- At least 10% of the lot has to stay uncovered and pervious.
Light Industrial - A two-family dwelling needs 0.459 acre here rather than the 0.23 acre lot minimum. At least 10% of the lot must also be left pervious, a separate requirement from the 40% building coverage cap.
- The 40 ft front yard is a minimum with no published maximum, so a building may sit further back.
Park - The Park district carries no dimensional standard of its own in this code, and it is not included in the density and dimensional requirements chart. That is by design rather than an omission.
- Since this district has no dimensional standard of its own, confirm with the building department which requirements and approval path apply before planning any construction here.
Planned Unit Development - A planned unit development requires at least 40 acres to create. Setbacks, coverage and other dimensions are not published in advance; they are set at the time the planned unit development is reviewed and approved under § 355-14.
- Confirm the standards that will apply to a specific project with the building department.
Residential One Family - 10,000 Sq. - The front yard is a band, 20 ft minimum and 30 ft maximum, so a house cannot sit further back than 30 ft. At least 50% of the lot must also be left pervious, a floor on uncovered ground separate from the 40% building coverage cap.
- A two-family dwelling needs 0.344 acre rather than 0.23 acre.
- A nonresidential use needs 0.918 acre.
- Senior housing takes a special use permit with site plan review, and then needs 6,000 sq ft of land per dwelling unit, with the pervious minimum dropping to 30%.
- An accessory building keeps 5 ft to the side lot line, not the 10 ft a house takes.
Residential Multi-Family - 10,000 Sq. - Multifamily is governed by land per unit: 6,000 sq ft of lot for each dwelling unit, alongside the 0.23 acre lot minimum. The front yard is a band as well, 20 ft minimum and 30 ft maximum.
- A two-family dwelling needs 0.344 acre rather than 0.23 acre.
- A nonresidential use needs 0.918 acre.
- Senior housing takes a special use permit with site plan review, on the same 6,000 sq ft of land per unit.
- At least 30% of the lot must be left pervious, a separate requirement from the 40% building coverage cap.
- An accessory building keeps 5 ft to the side lot line, not the 10 ft a house takes.
Residential Professional Office - The front yard is a band, 20 ft minimum and 30 ft maximum, so a house cannot sit further back than 30 ft. A two-family dwelling needs 0.344 acre rather than the 0.23 acre lot minimum.
- A professional office with an apartment is held to the same 0.23 acre lot minimum as a house.
- At least 10% of the lot must be left pervious, a separate requirement from the 40% building coverage cap.
- An accessory building keeps 5 ft to the side lot line, not the 10 ft a house takes.
Residential One Family - 15,000 Sq. - The front yard is a band, 20 ft minimum and 30 ft maximum. At least 50% of the lot must also be left pervious, a floor on uncovered ground separate from the 25% building coverage cap.
- A two-family dwelling needs 0.459 acre rather than the 0.344 acre lot minimum.
- A nonresidential use needs 0.918 acre.
Residential One Family - 20,000 Sq. - The front yard is a band, 25 ft minimum and 35 ft maximum. At least 50% of the lot must also be left pervious, a floor on uncovered ground separate from the 25% building coverage cap.
- A two-family dwelling needs 0.689 acre rather than the 0.459 acre lot minimum.
- A nonresidential use needs 0.918 acre.
Residential One Family - 40,000 Sq. - Elderly or senior housing and group family homes are allowed by special use permit with site plan review, and that route sets 6,000 square feet of land per dwelling unit, a 50 ft lot width, a 20 ft front setback and 40% building coverage.
- The 35 ft front setback is a minimum, and a building may sit no farther back than 50 ft.
- An accessory building keeps 10 ft to a side lot line, where a principal building takes 25 ft.
- A two-family dwelling needs a lot of at least 1.377 acres.
- Under that senior housing permit the side setback is 10 ft and the rear setback is 30 ft.
- At least 50% of the lot has to stay uncovered and pervious, separate from the building coverage cap.
Residential Conservation District - The front yard is a band, 35 ft minimum and 50 ft maximum. At least 50% of the lot must also be left pervious, a floor on uncovered ground separate from the 25% building coverage cap.
- A two-family dwelling needs 1.377 acres rather than the 0.918 acre lot minimum.
- An accessory building keeps 10 ft to a side lot line.
Residential Senior Citizen - Multifamily is governed by land per unit: 6,000 sq ft of lot for each dwelling unit, alongside the 0.23 acre lot minimum. The front yard is a band as well, 20 ft minimum and 30 ft maximum.
- A two-family dwelling needs 0.344 acre rather than 0.23 acre.
- A nonresidential use needs 0.918 acre.
- Senior housing takes a special use permit with site plan review, on the same 6,000 sq ft of land per unit.
- At least 30% of the lot must be left pervious, a separate requirement from the 40% building coverage cap.
Size limits on record in Altamont
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 Altamont:
- BusinessAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Central Business DistrictAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Light IndustrialAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- ParkAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential One Family - 10,000 Sq.An apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential Multi-Family - 10,000 Sq.An apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential Professional OfficeAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential One Family - 15,000 Sq.An apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential One Family - 20,000 Sq.An apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential One Family - 40,000 Sq.An apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential Conservation DistrictAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
- Residential Senior CitizenAn apartment inside the house may not exceed 40% of the habitable space as it stood before construction or 1,000 square feet, whichever is more restrictive, and two bedrooms.
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 National Grid 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. Altamont has no short term rental law of its own, so hosts answer to the 2025 New York State short term rental registry law. Confirm with the building department before counting on short term rental use of a home. Separate question from whether you can build the unit.
- Zoning codeecode360.com/AL2859
- Building dept(518) 861-8554
Sizing up a specific parcel in Altamont?
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Building a full house instead?
A standard-finish house in Altamont runs $202–265/sq ft, about $365k–475k at 1,800 sq ft , plus roughly $6,733 for a conforming lot. See what it costs to build a house in Altamont.
ADU cost in nearby towns
All Albany County towns: Albany (City) · Cohoes (City) · Watervliet (City) · Berne · Bethlehem · Coeymans · Colonie · Guilderland · Knox · New Scotland · Rensselaerville · Westerlo · Colonie (Village) · Green Island (Village) · Menands (Village) · Ravena (Village) · Voorheesville (Village)
More on Altamont: Can you build an ADU here? · Zoning for new construction · Albany County build cost
ADU cost in Altamont: common questions
How much does it cost to build an ADU in Altamont, NY?
An 800 sq ft accessory dwelling unit in Village of Altamont runs roughly $195k–260k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $130k–170k. 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 Altamont?
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 $247–323/sq ft against $202–265/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Altamont?
Village of Altamont has 13 districts. 5 districts allow ADUs with occupancy restrictions, 5 require a special-use permit, 2 do not. 1 district has incomplete data - verify with the building department at (518) 861-8554. Check the specific address with the free ADU checker before you spend money on design.
Can I rent an ADU in Altamont short term?
No local short-term-rental law on record - which is not the same as permission for Village of Altamont. 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 Albany 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 Village of Altamont vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-09-20; verify with the building department at (518) 861-8554 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.