Cohoes · ADU cost
What it costs to build an ADU in Cohoes, NY
An 800 sq ft accessory dwelling unit in Cohoes 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 Cohoes maps 16 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 Cohoes
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 Cohoes 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 |
|---|---|---|---|---|
| Office/Retail Commercial | 0.23 ac | 0 / 10 / 20 ft | 35 ft | No |
| Form-Based Code Boundary | — | — | — | — |
| Floodplain District (FD) | — | — | — | — |
| Historic Overlay District (HD) | — | — | — | — |
| Industrial | 0.23 ac | 20 / 20 / 20 ft | 45 ft | No |
| Land Conservation | 1 ac | 75 / 50 / 50 ft | 35 ft | No |
| Residential-Multi-Family | 0.23 ac | 5 / 10 / 20 ft | 35 ft | Occupancy restricted |
| Mixed-Use | 0.046 ac | 0 / 0 / 0 ft | 55 ft | No |
| Waterfront Mixed-Use | 0.12 ac | 0 / 0 / 0 ft | 45 ft | No |
| Mixed Use Civic Core | — | - / 0 / 5 ft | 45 ft | Occupancy restricted |
| Mixed Use Downtown Core | — | - / 0 / 5 ft | 45 ft | Occupancy restricted |
| Mixed-Use Neighborhood Corridor (MU-NC) | — | 0 / 0 / 10 ft | 36 ft | Occupancy restricted |
| Mixed-Use Transit Corridor (MU-TC) | — | - / 0 / 0 ft | 35 ft | Occupancy restricted |
| Planned Unit Development District (PDD) | — | — | — | — |
| Residential - 1 | 0.23 ac | 30 / 12 / 20 ft | 35 ft | Occupancy restricted |
| Residential - 2 | 0.17 ac | 5 / 10 / 20 ft | 35 ft | Occupancy restricted |
Office/Retail Commercial - The front setback is a range of 0 to 10 ft rather than the single figure shown. Schedule B publishes no residential row for this district: office, retail, cultural, indoor recreation and mixed-use structures all share these figures.
- Consult Schedule B, the schedule of area and bulk regulations at 285 Attachment 2, directly for any other use.
Form-Based Code Boundary - Chapter 285 names four form-based districts, and this is not one of them. No dimensional standard is published for it.
- It appears to mark the outer boundary the Regulating Plan Map (§ 285-167) draws around those four districts, rather than a district regulated on its own.
- The four form-based districts are named and defined at § 285-166 through § 285-171.
Floodplain District (FD) - In the FEMA-mapped flood hazard area this district controls how a structure is built rather than where it sits: elevation, floodproofing, anchoring and utility placement. It carries no lot size, setback, coverage or height standard of its own.
- The flood hazard construction standards are set out at § 285-45.
Historic Overlay District (HD) - This overlay adds design and appearance review of designated historic sites and districts. It carries no lot size, setback, coverage or height standard of its own and layers on top of whatever base district underlies the parcel.
- The review requirement is set out at § 285-44.
Industrial - The figures shown are the general industrial row, shared by a contractor's yard, light industry, a machine shop, manufacturing and a warehouse. Schedule B varies standards use by use, so another use here can carry different figures.
- A single-family dwelling is reachable only by special use permit, on 70 ft of width with a 30 ft front yard and 12 ft side yards.
- Consult Schedule B, the schedule of area and bulk regulations at 285 Attachment 2, directly for any use outside that group.
Land Conservation - The figures shown are the base row for a farm, greenhouse, hydroponics or municipal utility. A natural preserve or a commercial stable needs 10 acres against this 1 acre, with the same setbacks, and takes a special use permit.
- At least 80% of the lot must be left as green space, a floor that sits alongside the building coverage cap shown.
- Consult Schedule B, the schedule of area and bulk regulations at 285 Attachment 2, directly for any other use.
Residential-Multi-Family - These figures are the multifamily case. A single-family house needs less land here, not more: 0.115 acre on a 50 ft wide lot, with 5 ft side yards and up to 60% coverage.
- A two-family needs 0.138 acre on 60 ft of width, with 5 ft side yards and up to 70% coverage.
- An attached or row house needs 0.172 acre on 50 ft of width, with 5 ft side yards and up to 80% coverage.
- The front setback is a range, 5 to 15 ft.
- Many other uses carry their own rows in the area and bulk schedule, so standards for anything other than a home are worth checking there.
Mixed-Use - The 0 ft front, side and rear setbacks, the 100% coverage and the 55 ft height are the commercial and office case. A two-family drops out of that form: 0.172 acre, 50 ft of width, 10 ft side and 20 ft rear yards, and 35 ft of height.
- The front setback is a range, 0 to 5 ft.
- A single-family house needs 0.115 acre on 25 ft of width.
- An attached or row house, or a multifamily building, needs 0.057 acre on 25 ft of width.
- Many other uses carry their own rows in the area and bulk schedule, so standards for anything other than a home are worth checking there.
Waterfront Mixed-Use - The 0 ft front, side and rear setbacks, the 100% coverage and the 45 ft height are the retail, office and restaurant case. A single-family house takes its own standards: 0.184 acre, 80 ft of width and 10 ft front, side and rear yards.
- The front setback is a range, 0 to 10 ft.
- A multifamily building needs 0.23 acre on 90 ft of width.
- Many other uses carry their own rows in the area and bulk schedule, so standards for anything other than a home are worth checking there.
Mixed Use Civic Core - Front and side-street placement works as a build-to zone, 0 ft minimum and 5 ft maximum, so a building has to sit close to the street rather than merely behind a line. Height carries a 22 ft minimum as well as the 45 ft cap.
- The interior side property line takes a 0 ft minimum with no maximum.
- The 45 ft height cap is 4 stories.
- The ground floor must be in office or retail use.
- The district standards are set out at § 285-168.
Mixed Use Downtown Core - Front and side-street placement works as a build-to zone, 0 ft minimum and 5 ft maximum, so a building has to sit close to the street rather than merely behind a line. Height carries a 35 ft minimum as well as the 45 ft cap.
- The interior side property line takes a 0 ft minimum.
- The 45 ft height cap is 4 stories.
- The district standards are set out at § 285-169.
Mixed-Use Neighborhood Corridor (MU-NC) - Front and interior side placement works as a build-to zone, 0 ft minimum and 20 ft maximum, and the side-street build-to zone runs from 0 to 10 ft. Height carries a 15 ft minimum as well as the 36 ft cap.
- The 36 ft height cap is 3 stories.
- The district standards are set out at § 285-171.
Mixed-Use Transit Corridor (MU-TC) - Front, side-street and interior side placement all work as a build-to zone, 0 ft minimum and 10 ft maximum, so a building has to sit close to the line rather than merely behind it. Height carries a 15 ft minimum as well as the 35 ft cap.
- The 35 ft height cap is 3 stories.
- The district standards are set out at § 285-170.
Planned Unit Development District (PDD) - The Common Council approves a planned unit development case by case against a comprehensive development plan, largely independent of the land use regulations otherwise applicable to the property. The approved plan for the tract is the only source of dimensions.
- The district is set out at § 285-43.
Residential - 1 - At least 50% of the lot must be left as green space, a separate floor from the building coverage cap shown. Congregate housing takes the same figures as a single-family house.
- The 35 ft height cap applies to by-right uses; a public use is capped at 10 ft.
- Consult Schedule B, the schedule of area and bulk regulations at 285 Attachment 2, directly for any other use.
Residential - 2 - The front setback is published as a range of 5 to 10 ft, and at least 50% of the lot must be left as green space on top of the building coverage cap.
- Single-family, two-family and attached or row houses all take the same 7,500 sq ft lot and 50 ft width.
- Consult Schedule B, the schedule of area and bulk regulations at 285 Attachment 2, directly for any other use.
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 rentalsShort-term rentals allowed with local rules. Renting a home short term in Cohoes requires an annual permit from Code Enforcement, and short term rental operation is restricted to the mixed-use districts. The permit is $150 a year. Separate question from whether you can build the unit.
- Zoning codeecode360.com/CO0376
- Building dept(518) 233-2127
Sizing up a specific parcel in Cohoes?
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Building a full house instead?
A standard-finish house in Cohoes runs $202–265/sq ft, about $365k–475k at 1,800 sq ft , plus roughly $3,515 for a conforming lot. See what it costs to build a house in Cohoes.
ADU cost in nearby towns
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More on Cohoes: Can you build an ADU here? · Zoning for new construction · Albany County build cost
ADU cost in Cohoes: common questions
How much does it cost to build an ADU in Cohoes, NY?
An 800 sq ft accessory dwelling unit in City of Cohoes 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 Cohoes?
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 Cohoes?
City of Cohoes has 16 districts. 7 districts allow ADUs with occupancy restrictions, 5 do not. 4 districts have incomplete data - verify with the building department at (518) 233-2127. Check the specific address with the free ADU checker before you spend money on design.
Can I rent an ADU in Cohoes short term?
Short-term rentals allowed with local rules for City of Cohoes. 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 City of Cohoes vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-09-19; verify with the building department at (518) 233-2127 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.