Spencerport · ADU cost
What it costs to build an ADU in Spencerport, NY
An 800 sq ft accessory dwelling unit in Spencerport 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 Spencerport maps 1 district 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 Spencerport
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Monroe 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 Spencerport 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 |
|---|---|---|---|---|
| A District (Residential) | 0.28 ac | 50 / 6.4 / 7.5 ft | 35 ft | Occupancy restricted |
A District (Residential) - Side and rear setbacks grow with the lot: each side setback is 8% of the lot width measured along the street line, and each rear setback is 5% of the lot depth. The figures shown are for a lot at the 80 ft wide and 150 ft deep minimum.
- A two- or three-family dwelling needs Zoning Board approval and 6,500 sq ft per dwelling unit, with floor areas of 500 sq ft studio, 650 one-bedroom, 800 two-bedroom and 1,000 three-bedroom.
- A multiple-unit dwelling takes 50 ft front, 25 ft side, 40 ft rear, 3,500 sq ft per unit, two storeys, one three-bedroom unit per 8 units, and 60 ft between buildings front to front.
- The 25% building cap includes accessory structures. The separate 25% total cap counts impervious surfaces and improvements, driveway included, about 3,000 sq ft on the 12,000 sq ft minimum lot.
- Where buildings on both sides within 100 ft stand closer to the street than 50 ft, the closer setback may be applied; on a corner lot the front setback is measured along the narrower frontage.
- A through lot owes the front setback to each frontage unless the Code Enforcement Officer approves otherwise, and each lot is allowed one driveway.
- Under § 340-13 the minimum building area is 800 sq ft on the first floor of a one-and-one-half-storey house and 625 sq ft on each floor of a two-storey.
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 Village of Spencerport (municipal electric) 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. The Village of Spencerport has no local short-term rental law, and that is not the same as permission. Confirm with the Building Department before counting on the use. Separate question from whether you can build the unit.
- Zoning codeecode360.com/36639738
- Building dept(585) 352-4790
Sizing up a specific parcel in Spencerport?
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 Spencerport runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Spencerport.
ADU cost in nearby towns
All Monroe County towns: Rochester (City) · Brighton · Chili · Clarkson · Gates · Greece · Hamlin · Henrietta · Irondequoit · Mendon · Ogden · Parma · Penfield · Perinton · Pittsford · Riga · Rush · Sweden · Webster · Wheatland · East Rochester (Village) · Brockport (Village) · Churchville (Village) · Fairport (Village) · Hilton (Village) · Honeoye Falls (Village) · Pittsford (Village) · Scottsville (Village) · Webster (Village)
More on Spencerport: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Spencerport: common questions
How much does it cost to build an ADU in Spencerport, NY?
An 800 sq ft accessory dwelling unit in Village of Spencerport 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 Spencerport?
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 Spencerport?
Village of Spencerport has 1 district. The only district allows ADUs with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (585) 352-4790 before you spend money on design.
Can I rent an ADU in Spencerport short term?
No local short-term-rental law on record - which is not the same as permission for Village of Spencerport. 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 Monroe 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 Spencerport vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-13; verify with the building department at (585) 352-4790 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.