East Nassau · ADU cost
What it costs to build an ADU in East Nassau, NY
An 800 sq ft accessory dwelling unit in East Nassau runs roughly $195k–255k, or about $244–319/sq ft, and that per-square-foot figure sits deliberately above the $200–262/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 East Nassau maps 3 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
ADU cost by size in East Nassau
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Rensselaer County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $323–$424 | $130k–170k |
| 600 sq ft | One bedroom | $270–$354 | $160k–210k |
| 800 sq ft | One bedroom, larger | $244–$319 | $195k–255k |
| 1,000 sq ft | Two bedroom | $228–$299 | $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–$22 | $16 | — |
| Framing | $25–$31 | $25 | — |
| Envelope - roof, siding, windows | $31–$40 | $31 | — |
| Plumbing | $27–$33 | $16 | 55% |
| Electrical | $18–$23 | $12 | 35% |
| HVAC | $22–$28 | $14 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $32–$42 | $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 East Nassau 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 |
|---|---|---|---|---|
| Rural Residential District | 2 ac | 75 / 50 / 75 ft | — | As of right |
| Hamlet District | 2 ac | 25 / 25 / 25 ft | — | As of right |
| Waterfront Residential District | 2 ac | 50 / 50 / 50 ft | — | As of right |
Size limits on record in East Nassau
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 East Nassau:
- Rural Residential DistrictThe unit may not exceed 40% of the living space of the house or 1,000 square feet, whichever is less
- Hamlet DistrictThe unit may not exceed 40% of the living space of the house or 1,000 square feet, whichever is less
- Waterfront Residential DistrictThe unit may not exceed 40% of the living space of the house or 1,000 square feet, whichever is less
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. The Village's code is published at villageofeastnassau.gov: the 51-page Zoning Law is Local Law No. 1 of 2019, and the Local Laws page carries the full index through Local Law No. 1 of 2025 (Accessory Dwelling Units). Read in full 2026-08-27. THE GOVERNING PROVISION IS THE LODGING USE. Article on Definitions: 'LODGING: Any use of a building, in whole or in part, for the temporary overnight accommodations of guests or visitors for compensation or other consideration. Said term includes, but is not limited to, the following uses: hotel, motel, bed and breakfast, group home, boarding, lodging, or rooming house, AND THE RENTAL OF PRIVATE DWELLINGS, or portions thereof, or residential accessory buildings.' That last clause names whole-house and partial short-term renting outright — there is no need to argue by analogy. IN THE DISTRICT SCHEDULE OF USE REGULATIONS, 'Lodging' RUNS X* / X* / NP across the Village's three districts — Hamlet, Rural Residential and Waterfront Residential. READ THE LEGEND: here 'X designates a special permit use within the land use district — the use is not allowed until a special use permit is issued', '*' means site plan review is also required, and 'NP designates use prohibited by law within the land use district.' So a short-term rental in the Hamlet or Rural Residential district requires BOTH a special use permit and site plan approval, and IN THE WATERFRONT RESIDENTIAL DISTRICT IT IS PROHIBITED OUTRIGHT — a variance under Article X is the only route there. The Village uses the same X-means-special-permit convention as the surrounding Town of Nassau and as Castleton-on-Hudson; a reader carrying the more common meaning of X across would get this backwards. The schedule is also closed: 'Any use not specifically listed below is prohibited.' There is no separate short-term-rental permit, registration, occupancy cap, fee schedule or licence in the Village code — the entire regime is the special-permit and site-plan process for a Lodging use, which means the standards applied are the Village Board's site plan review standards rather than any STR-specific ones. Note the Village publishes at villageofeastnassau.gov; the .org address is a stale site that only redirects. Separately, New York State's 2025 STR registry requires every host statewide to register the unit through the Rensselaer County registry regardless of what the municipality allows. Confirm with the building department at (518) 794-0289 before listing. Separate question from whether you can build the unit.
- Building dept(518) 794-0289
Sizing up a specific parcel in East Nassau?
Aldo pulls the exact zoning district, setbacks, and build feasibility for any parcel — before you buy. Enter your email to open Aldo and run your free report.
Building a full house instead?
A standard-finish house in East Nassau runs $200–262/sq ft, about $360k–470k at 1,800 sq ft , plus roughly $13,658 for a conforming lot. See what it costs to build a house in East Nassau.
ADU cost in nearby towns
All Rensselaer County towns: Rensselaer (City) · Troy (City) · Berlin · Brunswick · East Greenbush · Hoosick · Nassau · North Greenbush · Poestenkill · Sand Lake · Schaghticoke · Schodack · Stephentown · Castleton-on-Hudson (Village) · Hoosick Falls (Village) · Nassau (Village)
More on East Nassau: Can you build an ADU here? · Zoning for new construction · Rensselaer County build cost
ADU cost in East Nassau: common questions
How much does it cost to build an ADU in East Nassau, NY?
An 800 sq ft accessory dwelling unit in Village of East Nassau runs roughly $195k–255k 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 East Nassau?
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 $244–319/sq ft against $200–262/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in East Nassau?
Village of East Nassau has 3 districts. All districts allow ADUs. Check the specific address with the free ADU checker or confirm with the building department at (518) 794-0289 before you spend money on design.
Can I rent an ADU in East Nassau short term?
Short-term rentals allowed with local rules for Village of East Nassau. 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 Rensselaer 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 East Nassau vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-05; verify with the building department at (518) 794-0289 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).