Round Lake · ADU cost
What it costs to build an ADU in Round Lake, NY
An 800 sq ft accessory dwelling unit in Round Lake runs roughly $200k–260k, or about $249–327/sq ft, and that per-square-foot figure sits deliberately above the $204–268/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 Round Lake maps 5 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 Round Lake
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Saratoga County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $331–$433 | $130k–175k |
| 600 sq ft | One bedroom | $276–$362 | $165k–215k |
| 800 sq ft | One bedroom, larger | $249–$327 | $200k–260k |
| 1,000 sq ft | Two bedroom | $233–$305 | $235k–305k |
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 | $28–$34 | $16 | 55% |
| Electrical | $18–$24 | $13 | 35% |
| HVAC | $23–$28 | $15 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $32–$43 | $27 | 15% |
| Millwork & cabinetry | $18–$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 Round Lake 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 |
|---|---|---|---|---|
| RV-1 Residential | 0.32 ac | 40 / 20 / 50 ft | 35 ft | No |
| RV-2 Residential | 0.16 ac | 20 / 10 / 30 ft | 30 ft | No |
| CV-1 Commercial | 0.69 ac | 40 / 30 / 30 ft | 35 ft | No |
| LCV Land Conservation | 10 ac | — | — | No |
| M-PV Parks and Municipal | — | — | — | No |
RV-1 Residential - The 15% coverage cap counts everything on the parcel, so the 14,000 sq ft minimum lot carries a footprint of 2,100 sq ft in total. Start a feasibility here from the coverage line rather than the setbacks.
- The lot minimum is sewer-conditional and the penalty is 43%: table note 1 raises it from 14,000 sq ft to 20,000 sq ft where public sewer is not available at the time of construction.
- An accessory structure has its own tighter standards: 40 ft front, 7 ft side, 10 ft rear and a 12 ft height cap.
- RV-1 permits single-family dwellings only and does not permit a two-family dwelling.
- A minimum available building area of 1,000 sq ft also applies; it reads either as a floor on house size or on the area left for building once the setbacks are taken. Confirm which with the Village.
- The Village's architectural standards must be met for all new construction here, a design review layer on top of the dimensional one.
- A local law adopted 4-15-2026 broadened what counts as an accessory, so more structures fall under the accessory setbacks and height; check it before treating a structure as exempt.
RV-2 Residential - One- and two-family dwellings are both principal permitted uses, so a duplex needs no special permit and no extra land. The 20% coverage cap counts everything on the parcel, which leaves a 1,400 sq ft footprint on the 7,000 sq ft minimum lot.
- An accessory structure has its own tighter standards: 20 ft front, three feet to the side and three to the rear, and an 8 ft height cap.
- A professional office - physician, dentist, lawyer, engineer, architect, accountant - is permitted within a dwelling occupied by that same person, with off-street parking for clients.
- A minimum available building area of 900 sq ft also applies; it reads either as a floor on house size or on the area left for building once the setbacks are taken. Confirm which with the Village.
- A local law adopted 4-15-2026 broadened what counts as an accessory, so more structures fall under the accessory setbacks and height; check it before treating a structure as exempt.
CV-1 Commercial - The 15% coverage cap counts everything on the parcel, so the 30,000 sq ft minimum lot carries a 4,500 sq ft footprint. This district is designed to keep commercial buildings freestanding and well set back, not to make a main street.
- An accessory structure has its own tighter standards: 40 ft front, 10 ft side, 15 ft rear and a 12 ft height cap.
- A minimum available building area of 1,200 sq ft also applies; it reads either as a floor on building size or on the area left for building once the setbacks are taken. Confirm which with the Village.
- A local law adopted 4-15-2026 broadened what counts as an accessory, so more structures fall under the accessory setbacks and height; check it before treating a structure as exempt.
LCV Land Conservation - The uses here are not housing: customary agricultural operations, golf and country clubs, and small accessory buildings serving them. Anything built runs through the special permit and site plan process, where the Planning Board sets the terms case by case.
- The code sets no frontage, coverage, setback or height for this district, so the envelope comes out of the special permit and the site plan rather than from published figures.
- The 10 acre minimum attaches to large structures as defined in § 180-16B rather than to every use, so read § 180-16 before applying it.
- Raising poultry or livestock needs a special permit, while sale of produce grown on the premises is permitted.
- Accessory structures are available by special permit only.
M-PV Parks and Municipal - The code sets no lot area, frontage, coverage, setback or height for M-PV. The standards are those of the special use permit where one is required, so the Planning Board sets the envelope case by case.
- Parks and municipal structures are the principal uses here.
Size limits on record in Round Lake
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 Round Lake:
- RV-1 ResidentialIn RV-2 the 20% coverage cap on a 7,000 sq ft lot allows a 1,400 sq ft footprint for the house and everything else on the parcel.
- RV-2 ResidentialIn RV-2 the 20% coverage cap on a 7,000 sq ft lot allows a 1,400 sq ft footprint for the house and everything else on the parcel.
- CV-1 CommercialIn RV-2 the 20% coverage cap on a 7,000 sq ft lot allows a 1,400 sq ft footprint for the house and everything else on the parcel.
- LCV Land ConservationIn RV-2 the 20% coverage cap on a 7,000 sq ft lot allows a 1,400 sq ft footprint for the house and everything else on the parcel.
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. A short-term rental in the Village of Round Lake needs a special use permit from the Zoning Board of Appeals, and the owner must be domiciled in the dwelling that holds the rental unit for at least nine thirty-consecutive-day periods in each of the permit's two years. Separate question from whether you can build the unit.
- Zoning codeecode360.com/49586803
- Building dept(518) 899-2800
Sizing up a specific parcel in Round Lake?
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Building a full house instead?
A standard-finish house in Round Lake runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Round Lake.
ADU cost in nearby towns
All Saratoga County towns: Mechanicville (City) · Saratoga Springs (City) · Ballston · Charlton · Clifton Park · Corinth · Day · Edinburg · Galway · Greenfield · Halfmoon · Malta · Milton · Moreau · Northumberland · Providence · Saratoga · Stillwater · Waterford · Wilton · Ballston Spa (Village) · Corinth (Village) · Schuylerville (Village) · South Glens Falls (Village) · Stillwater (Village) · Victory (Village) · Waterford (Village)
More on Round Lake: Can you build an ADU here? · Zoning for new construction · Saratoga County build cost
ADU cost in Round Lake: common questions
How much does it cost to build an ADU in Round Lake, NY?
An 800 sq ft accessory dwelling unit in Village of Round Lake runs roughly $200k–260k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $130k–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 Round Lake?
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 $249–327/sq ft against $204–268/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Round Lake?
Village of Round Lake has 5 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (518) 899-2800 before you spend money on design.
Can I rent an ADU in Round Lake short term?
Short-term rentals allowed with local rules for Village of Round Lake. 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 Saratoga 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 Round Lake vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-02; verify with the building department at (518) 899-2800 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.