Hudson · ADU cost
What it costs to build an ADU in Hudson, NY
An 800 sq ft accessory dwelling unit in Hudson 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 city 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 City of Hudson maps 12 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 Hudson
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Columbia 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 Hudson 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 |
|---|---|---|---|---|
| One-Family Residential | 0.11 ac | 20 / 10 / 30 ft | 35 ft | Occupancy restricted |
| One- or Two-Family Residential | 0.09 ac | 15 / 7.5 / 30 ft | 35 ft | Occupancy restricted |
| Multiple Dwelling Residential | 0.18 ac | 10 / 10 / 30 ft | 35 ft | Occupancy restricted |
| Multiple Dwelling (High-Density) | 0.14 ac | 10 / 10 / 30 ft | 45 ft | Occupancy restricted |
| Institutional-Residential Conservation | 0.23 ac | 20 / 15 / 30 ft | 35 ft | Occupancy restricted |
| Riverfront Gateway | 0.14 ac | 10 / 10 / 30 ft | 45 ft | Occupancy restricted |
| Core Riverfront | 0.14 ac | 10 / 10 / 20 ft | 35 ft | Occupancy restricted |
| Recreational Conservation | 0.28 ac | 20 / 15 / 30 ft | 35 ft | Occupancy restricted |
| City Core Commercial | — | — | 45 ft | Occupancy restricted |
| Commerce District | 0.11 ac | - / - / 20 ft | 35 ft | Occupancy restricted |
| General Commercial | 0.23 ac | - / 10 / 20 ft | 35 ft | Occupancy restricted |
| Industrial | — | - / 10 / 10 ft | 45 ft | Occupancy restricted |
One-Family Residential - The Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street, instead of the figure shown.
- The minimum lot area is for one family on one lot, not a figure per dwelling unit.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
One- or Two-Family Residential - The Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street, instead of the figure shown.
- The figures shown apply to one- or two-family dwellings.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Multiple Dwelling Residential - The figures shown are for multiple dwellings. Each dwelling unit needs 400 sq ft of usable open space, and the maximum building length is 160 ft.
- A one- or two-family dwelling takes a different column: 0.0918 acres on 40 ft of width, with a 15 ft front, 7.5 ft side and 30 ft rear yard, 35% coverage and 2,400 sq ft per dwelling unit.
- An attached dwelling needs 20 ft of lot width per unit, 35 ft for an end unit including a 15 ft side yard, and 2,000 sq ft per dwelling unit with no total lot area stated.
- New office buildings, or buildings combining office and residential use, need 10,000 sq ft on a 100 ft lot, with a 10 ft front, 15 ft side and 30 ft rear yard and 30% coverage.
- The Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street, instead of the figure shown.
- Density and lot count are calculated on net parcel size under § 325-18C, and Article V sets alternative dimensions for conservation development and incentive zoning.
Multiple Dwelling (High-Density) - The side yard is ten feet or half the building height, whichever is greater. Each dwelling unit needs 300 sq ft of usable open space, and the maximum building length is 160 ft.
- A one- or two-family dwelling takes a different column: 0.0918 acres on 40 ft of width, with a 15 ft front, 7.5 ft side and 30 ft rear yard, 35 ft of height, 35% coverage and 2,400 sq ft per unit.
- An attached dwelling needs 20 ft of lot width per unit, 2,000 sq ft per dwelling unit with no total lot area stated, and 400 sq ft of usable open space per unit.
- The figures shown are for multiple dwellings; one- or two-family dwellings and attached dwellings have separate standards.
- The Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street, instead of the figure shown.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Institutional-Residential Conservation, Recreational Conservation - Each dwelling unit needs 500 sq ft of usable open space, and the Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Riverfront Gateway - The side yard is ten feet or half the building height, whichever is greater. Each dwelling unit needs 300 sq ft of usable open space, and the maximum building length is 160 ft.
- The Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street, instead of the figure shown.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Core Riverfront - Each dwelling unit needs 400 sq ft of usable open space, and the Planning Board may approve a front yard that conforms with the prevailing building setback on the property's street.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
City Core Commercial - No side yard is required, but one that is provided must be at least ten feet. Within 25 ft of a residence district boundary the side yard becomes 10 ft and the rear yard 30 ft.
- Height is also limited to four stories.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Commerce District - No side yard is required, but one that is provided must be at least ten feet. Within 25 ft of a residence district boundary the side yard becomes 10 ft and the rear yard 30 ft.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
General Commercial - Within 25 ft of a residence district boundary the side yard becomes 15 ft and the rear yard 30 ft. Area devoted to manufacturing is capped at 10,000 sq ft.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Industrial - Height is limited to two feet for each foot of distance from any property line, up to 45 ft. Within 25 ft of a residence district boundary the side and rear yards both become 40 ft.
- Density and the number of lots a parcel may be subdivided into are calculated on net parcel size under § 325-18C.
- Article V sets alternative dimensions for conservation development and incentive zoning.
Size limits on record in Hudson
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 Hudson:
- One-Family ResidentialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- One- or Two-Family ResidentialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Multiple Dwelling ResidentialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Multiple Dwelling (High-Density)One ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Institutional-Residential ConservationOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Riverfront GatewayOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Core RiverfrontOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Recreational ConservationOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- City Core CommercialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- Commerce DistrictOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- General CommercialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
- IndustrialOne ADU per building lot, at least 350 sq ft and no larger than the gross floor area of the principal dwelling.
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. Hudson requires owner occupancy for a short-term rental, and licenses are capped at 25 city-wide with a maximum of 15 per planning district. A moratorium on new licenses was adopted in June 2024. Separate question from whether you can build the unit.
- Zoning codeecode360.com/5082256
- Building dept(518) 828-3133
Sizing up a specific parcel in Hudson?
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Building a full house instead?
A standard-finish house in Hudson runs $202–265/sq ft, about $365k–475k at 1,800 sq ft , plus roughly $24,800 for a conforming lot. See what it costs to build a house in Hudson.
ADU cost in nearby towns
All Columbia County towns: Ancram · Austerlitz · Canaan · Chatham · Claverack · Clermont · Copake · Gallatin · Germantown · Ghent · Hillsdale · Kinderhook · Livingston · New Lebanon · Stockport · Stuyvesant · Taghkanic · Chatham (Village) · Kinderhook (Village) · Philmont (Village) · Valatie (Village)
More on Hudson: Can you build an ADU here? · Zoning for new construction · Columbia County build cost
ADU cost in Hudson: common questions
How much does it cost to build an ADU in Hudson, NY?
An 800 sq ft accessory dwelling unit in City of Hudson 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 Hudson?
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 Hudson?
City of Hudson has 12 districts. All districts allow ADUs with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (518) 828-3133 before you spend money on design.
Can I rent an ADU in Hudson short term?
Short-term rentals allowed with local rules for City of Hudson. 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 Columbia 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 City of Hudson vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-06-02; verify with the building department at (518) 828-3133 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.