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.
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) — Spencerport's single residential district, so every house in the village is answered from this one row. 12,000 sf (0.28 acres) with a minimum lot width of 80 ft and a MINIMUM LOT DEPTH OF 150 FT, and a maximum residential building height of 35 ft. THE SIDE AND REAR SETBACKS ARE BOTH PERCENTAGE FORMULAS, WHICH IS UNIQUE IN THIS COUNTY — every other percentage setback in the Monroe dataset keys only the side yard. § 340-12B(1) sets the front building line setback at a flat 50 ft to the street line, then provides that EACH SIDE SETBACK SHALL EQUAL 8% OF THE WIDTH OF THE LOT MEASURED ALONG THE STREET LINE and EACH REAR SETBACK SHALL EQUAL 5% OF THE DEPTH OF THE LOT. Evaluated at the district's own minimum dimensions that gives 6.4 FT per side (8% of 80 ft) and 7.5 FT at the rear (5% of 150 ft), which are the recorded figures. THESE GROW ON A LARGER LOT, unlike Riga's formula which keys to the required rather than the actual dimension: a 120 ft wide lot owes 9.6 ft per side, and a 200 ft deep lot owes 10 ft at the rear. Recompute both from the actual parcel rather than using the recorded values on anything above the minimum. MAXIMUM LOT COVERAGE IS NULL BY DELIBERATE CHOICE, NOT BECAUSE NONE IS STATED. § 340-11B caps each residential lot at 25% of its area covered by IMPERVIOUS SURFACES AND/OR IMPROVEMENTS, expressly including but not limited to the residential building — so driveways, parking and patios consume it alongside the house. Following the Penfield and Hamlin precedent in this county, a pavement-inclusive cap is not comparable to a building-coverage percentage and is documented here rather than recorded in the field. THE 25% IMPERVIOUS CAP IS NONETHELESS THE BINDING SITE CONSTRAINT and should be modelled directly: on the 12,000 sf minimum it allows about 3,000 sf of total impervious area for house, garage, drive and walks combined. § 340-11A adds a rule with no equivalent elsewhere in the dataset — NO MORE THAN ONE DRIVEWAY per residential lot. CORNER AND THROUGH LOTS ARE HANDLED EXPLICITLY: on a corner lot the required front setback is measured along the street on which the lot has the NARROWER frontage, and where frontages are equal the GREATER of the two required front setbacks applies; a through lot fronting two parallel streets owes the front setback to EACH frontage unless the Code Enforcement Officer approves otherwise. The chapter's lot and yard requirements were amended 12-3-2025 by L.L. No. 5-2025, so these are current figures. | 0.2755 ac | 50 / 6.4 / 7.5 ft | 35 ft | Occupancy restricted |
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. NO SHORT-TERM RENTAL PROVISION EXISTS IN SPENCERPORT. Article II A Districts: Residential (58,846 characters, covering the whole residential district including its permitted uses, special use regulations and planned residential development section) returns nothing for 'short-term rental', 'tourist home' or 'bed-and-breakfast' in either hyphenation, and all 52 chapters of the Village Code were enumerated from the eCode360 table of contents and swept for a rental, lodging, licensing, registration or occupancy chapter — none exists. That whole-code step is mandatory in this county: Mendon hides a full STR operating-permit regime in Ch. 208, Gates in Ch. 148, and the Village of Pittsford requires both a zoning permission under its Article 29 and a separate Ch. 154 rental property permit. Spencerport's negative is therefore tested rather than assumed. THE VILLAGE HAS NO COMMERCIAL LODGING USE IN ITS RESIDENTIAL DISTRICT AT ALL — no bed-and-breakfast, no tourist home — which puts it with Riga, Wheatland and Scottsville at the restrictive end of the county and apart from Churchville, Honeoye Falls, Brockport and the Village of Pittsford, all of which permit a bed-and-breakfast somewhere. ABSENCE IS NOT PERMISSION: § 340-9 states the A District's permitted uses as a closed list (amended 9-1-2021 by L.L. No. 3-2021), so an unlisted whole-house short-term rental is not authorised by silence. strStatus is recorded 'unknown' rather than 'prohibited' only because that reading has not been confirmed with the Village. NOTE THAT SPENCERPORT'S ZONING CHAPTER IS ACTIVELY MAINTAINED — the lot and yard requirements were amended as recently as 12-3-2025 by L.L. No. 5-2025 — so this is a current code rather than a stale one, and a future STR amendment is plausible. New York State's 2025 statewide short-term rental registry (Ch. 99 of the Laws of 2025) obliges every host to register regardless of local law. Confirm with the Building Department at (585) 352-4790. Separate question from whether you can build the unit.
- 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 · Town/Village of 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: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).