Coeymans · ADU cost
What it costs to build an ADU in Coeymans, NY
An 800 sq ft accessory dwelling unit in Coeymans 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 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 Coeymans maps 14 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 Coeymans
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 Coeymans 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 |
|---|---|---|---|---|
| General Business | 0.57 ac | 15 / 15 / 15 ft | 60 ft | No |
| Planned Commercial | 0.57 ac | 15 / 15 / 15 ft | — | No |
| Community Facility - 1 | — | 25 / 25 / 25 ft | — | No |
| Community Facility - 2 | — | — | — | No |
| Industrial - 1 | 0.92 ac | 50 / 50 / 50 ft | — | No |
| Industrial - 2 | 0.92 ac | 50 / 50 / 50 ft | — | No |
| Planned Industrial | 0.92 ac | 50 / 50 / 50 ft | — | No |
| Industrial Buffer | — | — | — | No |
| Single-Family Residence | 0.34 ac | 25 / 15 / 40 ft | 35 ft | No |
| Single & Two Family Residence | 0.23 ac | 25 / 10 / 15 ft | 30 ft | No |
| Multifamily Residence | — | 15 / 15 / 20 ft | 40 ft | No |
| Planned Residential | 0.34 ac | 25 / 15 / 15 ft | 30 ft | No |
| Residential & Agricultural | 1.84 ac | 40 / 30 / 50 ft | 40 ft | No |
| Residential Agricultural Limited | — | — | — | No |
General Business - Hotels and apartment houses are principal permitted uses in B-1. The schedule publishes no lot coverage percentage here, for principal or accessory buildings.
Planned Commercial - Every use in C-1P requires site plan review. The schedule publishes no lot coverage percentage here, for principal or accessory buildings.
- The schedule publishes the minimum lot area as 25,000 sq ft.
Community Facility - 1 - The schedule sets only setbacks in CF-1, 25 ft to the front, rear and side, and publishes nothing for lot area, lot width, coverage or height.
Community Facility - 2 - The schedule publishes no dimensional figure of any kind for CF-2. It lists only the district's uses, sewage treatment facilities and resident custodial housing.
Industrial - 1 - The schedule publishes no maximum height for I-1. I-1, I-2 and I-3P share one dimensional row and differ only in permitted use, not in bulk.
- Coverage for accessory buildings is marked Total rather than a percentage.
Industrial - 2 - The schedule publishes no maximum height for I-2. I-1, I-2 and I-3P share one dimensional row and differ only in permitted use, not in bulk.
- Coverage for accessory buildings is marked Total rather than a percentage.
Planned Industrial - The schedule publishes no maximum height for I-3P. I-1, I-2 and I-3P share one dimensional row and differ only in permitted use, not in bulk.
- Every use in I-3P requires site plan review.
- Coverage for accessory buildings is marked Total rather than a percentage.
Industrial Buffer - The schedule publishes no figures for I-B. Its entry points to the supplementary regulations instead.
Single-Family Residence - Where neither water nor sewer is available the parcel is governed by the Residential and Agricultural standards instead, and the lot minimum goes from 15,000 sq ft to 80,000.
- Without water and sewer the lot needs 1.8365 acres, the front yard 40 ft, the side yards 30 ft each and 60 ft combined, and the rear yard 50 ft.
- In that same case building coverage is halved, from 30% of the lot to 15%, while the height ceiling rises to 40 ft and three storeys.
- The side yard is a pair: 15 ft on one side and 30 ft for the two combined.
- Minimum first-floor living area is 900 sq ft for a one-storey house and 750 sq ft for two to 2 1/2 storeys.
- Accessory buildings are capped separately, by a share of the lot and by minimum distances to the house and to the side and rear lot lines.
Single & Two Family Residence - The 800 sq ft minimum first-floor area applies to a one-storey house; for two to 2 1/2 storeys it is 650 sq ft. Single-family and two-family dwellings are both permitted by right in R-2, on one shared set of figures.
- The schedule caps accessory buildings separately, by percent of lot and by minimum distance to the principal building and to the side and rear lot lines.
Multifamily Residence - R-3 sets no flat minimum lot area. The schedule publishes 2,500 sq ft per dwelling unit and nothing else, so the number of units sets the land needed.
- Minimum first-floor area is 1,200 sq ft for a one-storey building and 1,000 sq ft for two to three storeys.
- Row houses, apartment houses and garden apartments are all principal permitted uses in R-3.
- The schedule caps accessory buildings separately, by percent of lot and by minimum distance to the principal building and to the side and rear lot lines.
Planned Residential - Every use in R-4P requires site plan review and approval. The 800 sq ft minimum first-floor area applies to a one-storey house; for two to three storeys it is 650 sq ft.
- The schedule caps accessory buildings separately, by percent of lot and by minimum distance to the principal building and to the side and rear lot lines.
Residential & Agricultural - R-A governs more land than the map shows for it: an R-1 parcel is governed as R-A wherever public water and sewer are unavailable.
- The 750 sq ft minimum first-floor area applies to dwellings only, not to the district's farm and agricultural uses.
- The schedule caps accessory buildings separately, by percent of lot and by minimum distance to the principal building and to the side and rear lot lines.
Residential Agricultural Limited - The schedule gives R-A1 its own row of uses but leaves every dimensional column blank, so it publishes no lot area, width, coverage, setback or height.
- The district's uses are all those of R-A, plus motels, golf courses, sand and gravel pits and gasoline stations by special permit.
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. Coeymans has no local short-term rental law, and that is not the same as permission. Confirm with the building department before counting on short-term rental income. Separate question from whether you can build the unit.
- Zoning codeecode360.com/CO0785
- Building dept(518) 756-2850
Sizing up a specific parcel in Coeymans?
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Building a full house instead?
A standard-finish house in Coeymans runs $202–265/sq ft, about $365k–475k at 1,800 sq ft , plus roughly $1,640 for a conforming lot. See what it costs to build a house in Coeymans.
ADU cost in nearby towns
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More on Coeymans: Can you build an ADU here? · Zoning for new construction · Albany County build cost
ADU cost in Coeymans: common questions
How much does it cost to build an ADU in Coeymans, NY?
An 800 sq ft accessory dwelling unit in Town of Coeymans 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 Coeymans?
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 Coeymans?
Town of Coeymans has 14 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (518) 756-2850 before you spend money on design.
Can I rent an ADU in Coeymans short term?
No local short-term-rental law on record - which is not the same as permission for Town of Coeymans. 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 Town of Coeymans 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) 756-2850 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.