Gardiner · ADU cost
What it costs to build an ADU in Gardiner, NY
An 800 sq ft accessory dwelling unit in Gardiner runs roughly $200k–265k, or about $252–330/sq ft, and that per-square-foot figure sits deliberately above the $206–270/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 Gardiner maps 8 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 Gardiner
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Ulster County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $334–$438 | $135k–175k |
| 600 sq ft | One bedroom | $280–$366 | $170k–220k |
| 800 sq ft | One bedroom, larger | $252–$330 | $200k–265k |
| 1,000 sq ft | Two bedroom | $236–$309 | $235k–310k |
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 | $17–$23 | $17 | — |
| Framing | $26–$32 | $26 | — |
| Envelope - roof, siding, windows | $32–$41 | $32 | — |
| Plumbing | $28–$34 | $17 | 55% |
| Electrical | $19–$24 | $13 | 35% |
| HVAC | $23–$29 | $15 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $33–$44 | $28 | 15% |
| Millwork & cabinetry | $19–$28 | $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 Gardiner 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 |
|---|---|---|---|---|
| RA Rural Agricultural | 5 ac | 30 / 30 / 50 ft | 35 ft | As of right |
| HM Hamlet Mixed-Use | 1.8365 ac | 10 / 10 / 15 ft | 45 ft | As of right |
| HR Hamlet Residential | 1.8365 ac | 10 / 15 / 15 ft | 40 ft | As of right |
| CLI Commercial/Light Industrial | 2 ac | 40 / 20 / 50 ft | 35 ft | As of right |
| HC Highway Commercial | 2 ac | 30 / 20 / 50 ft | 35 ft | Special permit |
| SP-1 Shawangunk Ridge Protection | 5 ac | 75 / 50 / 100 ft | 35 ft | As of right |
| SP-2 Shawangunk Ridge Protection (Middle Slope) | 10 ac | 75 / 50 / 100 ft | 25 ft | Special permit |
| SP-3 Shawangunk Ridge Protection (Upper Slope) | 20 ac | 75 / 50 / 100 ft | 25 ft | Special permit |
RA Rural Agricultural — The recorded width is the minimum ROAD FRONTAGE for a conventional subdivision on a TOWN road; the table publishes no lot width at all. Minimum road frontage on a county or state road is 300 ft. The setbacks shown are for CONVENTIONAL development (§ 220-74); in an open space development they are set by § 220-20E and the minimum lot size by § 220-11D. Maximum base density in an open space development is 2 acres per dwelling unit before bonuses. Maximum footprint for a nonresidential structure 6,000 sq ft. The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
HM Hamlet Mixed-Use — THE BASE ROW IS THE UNSERVICED CASE, AND IT IS 80,000 SQ FT. The Dimensional Table prints no acreage for HM — the cell carries footnote 4, which sends the reader to § 220-11D, where the minimum runs 80,000 sq ft with neither utility, 40,000 with water only, 20,000 with sewage only and 10,000 with both. § 220-11E caps the result at 8 dwelling units per acre of buildable land however the lot-size and density provisions combine, counting a studio as 0.5 of a unit, a one-bedroom as 0.67 and a two-bedroom as 0.75. Front yard is a MINIMUM/MAXIMUM range: 10 ft to 25 ft on a town or private road and 15 ft to 35 ft on a county or state road, and a build-to line may be set to hold the street wall. The side yard may be 0 for a party-wall or zero-lot-line building and may be reduced by the Planning Board to suit hamlet context (table note 11). Minimum road frontage 40 ft on a town road and 50 ft on a county or state road. Maximum footprint for a nonresidential structure 10,000 sq ft, which may rise to 60,000 for a supermarket, cinema or similar destination use meeting the special permit impact criteria (table note 12). The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
HR Hamlet Residential — THE BASE ROW IS THE UNSERVICED CASE, AND IT IS 80,000 SQ FT. The Dimensional Table prints no acreage for HR — the cell carries footnote 4, which sends the reader to § 220-11D, where the minimum runs 80,000 sq ft with neither utility, 40,000 with water only, 20,000 with sewage only and 10,000 with both. § 220-11E caps the result at 8 dwelling units per acre of buildable land however the lot-size and density provisions combine, counting a studio as 0.5 of a unit, a one-bedroom as 0.67 and a two-bedroom as 0.75. Front yard is a MINIMUM/MAXIMUM range: 10 ft to 25 ft on a town or private road and 15 ft to 40 ft on a county or state road, and a build-to line may be set to hold the street wall. The side yard may be 0 for a party-wall or zero-lot-line building and may be reduced by the Planning Board to suit hamlet context (table note 11). Minimum road frontage 40 ft on a town road and 50 ft on a county or state road. Maximum footprint for a nonresidential structure 1,000 sq ft. The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
CLI Commercial/Light Industrial — The recorded width is the minimum ROAD FRONTAGE for a conventional subdivision on a TOWN road; the table publishes no lot width at all. Minimum road frontage on a county or state road is 200 ft, and the front yard there is 125 ft against 40 ft on a town road. WHERE THE LOT ABUTS A RESIDENTIAL DISTRICT the side and rear setbacks become 100 ft with a wooded buffer, for structures, driveways, parking and any paved area (table note 7). Maximum footprint for a nonresidential structure 200,000 sq ft. The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
HC Highway Commercial — The recorded width is the minimum ROAD FRONTAGE for a conventional subdivision on a TOWN road; the table publishes no lot width at all. Minimum road frontage on a county or state road is 300 ft, and the front yard there is 40 ft against 30 ft on a town road. WHERE THE LOT ABUTS A RESIDENTIAL DISTRICT the side and rear setbacks become 100 ft with a wooded buffer, for structures, driveways, parking and any paved area (table note 7). Maximum footprint for a nonresidential structure 60,000 sq ft. The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
SP-1 Shawangunk Ridge Protection — The recorded width is the minimum ROAD FRONTAGE for a conventional subdivision on a TOWN road; the table publishes no lot width at all. Minimum road frontage on a county or state road is 300 ft. Maximum base density in an open space development is 5 acres per dwelling unit before bonuses; open space lot sizes and setbacks are set by §§ 220-11D and 220-20E. Maximum footprint for a nonresidential structure 6,000 sq ft. The coverage figure is MAXIMUM IMPERVIOUS SURFACE, not building coverage (§ 220-74). It applies to each lot and to a whole subdivision including new roads, does not apply to agricultural uses or pre-existing nonconforming lots, and the Planning Board may waive it for HM lots. An applicant may exceed it using partially permeable materials under § 220-11C.
SP-2 Shawangunk Ridge Protection (Middle Slope), SP-3 Shawangunk Ridge Protection (Upper Slope) — SP-2 and SP-3 are NOT in the § 220-11 Dimensional Table — their dimensional regulations are in § 220-16, which this pass did not read. The figures here are unchanged and are not sourced from the Dimensional Table.
Size limits on record in Gardiner
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 Gardiner:
- SP-2 Shawangunk Ridge Protection (Middle Slope)Residential accessory structures (garages, guest cottages, sheds, pools, etc.) require a special permit per §220-16I Use Table. Single-family dwelling also requires special permit. Additions under 750 sq ft cumulative do not require special permit per §220-16I note.
- SP-3 Shawangunk Ridge Protection (Upper Slope)Residential accessory structures require a special permit per §220-16I Use Table. Single-family dwelling requires special permit. No residential units may be built in SP-3 unless the entire parcel is located within SP-3 (§220-16I note 10). Additions under 750 sq ft cumulative do not require 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 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-rental status not confirmed. The Town of Gardiner was actively drafting STR regulations as of 2024 — status may have changed. Contact Town of Gardiner at (845) 255-9675 to confirm current requirements before purchasing with STR income as a financial assumption. Separate question from whether you can build the unit.
- Zoning codeecode360.com/GA1939
- Building dept(845) 255-9675
Sizing up a specific parcel in Gardiner?
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 Gardiner runs $206–270/sq ft, about $370k–485k at 1,800 sq ft , plus roughly $44,164 for a conforming lot. See what it costs to build a house in Gardiner.
ADU cost in nearby towns
All Ulster County towns: Kingston (City) · Denning · Esopus · Hardenburgh · Hurley · Lloyd · Marbletown · Marlborough · New Paltz · Olive · Plattekill · Rochester · Rosendale · Saugerties · Shandaken · Shawangunk · Ulster · Wawarsing · Woodstock
More on Gardiner: Can you build an ADU here? · Zoning for new construction · Ulster County build cost
ADU cost in Gardiner: common questions
How much does it cost to build an ADU in Gardiner, NY?
An 800 sq ft accessory dwelling unit in Town of Gardiner runs roughly $200k–265k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $135k–175k. 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 Gardiner?
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 $252–330/sq ft against $206–270/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Gardiner?
Town of Gardiner has 8 districts. 5 districts allow ADUs, 3 require a special-use permit. Check the specific address with the free ADU checker or confirm with the building department at (845) 255-9675 before you spend money on design.
Can I rent an ADU in Gardiner short term?
Short-term-rental status not confirmed for Town of Gardiner. 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 Ulster 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 Gardiner vary by district and often carry exceptions this page does not show; zoning last reviewed Apr 2026; verify with the building department at (845) 255-9675 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).