Town/Village of East Rochester · ADU cost
What it costs to build an ADU in Town/Village of East Rochester, NY
An 800 sq ft accessory dwelling unit in Town/Village of East Rochester 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 Town/Village of East Rochester 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 Town/Village of East Rochester
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 Town/Village of East Rochester 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 |
|---|---|---|---|---|
| R-1-70 Residential District — 7,000 sf (0.16 acres) minimum lot area with 50 ft of lot width, front yard 25 ft, rear yard 20 ft, side yards 5 ft on one side and 10 ft both sides combined, maximum building height 35 ft, maximum building coverage 35% and A MINIMUM GREEN SPACE OF 30%. The larger of the village's two single-family districts, and still one of the smallest single-family minimums in Monroe County — East Rochester is a dense former railroad-shop village and its 'large lot' district is under a sixth of an acre. SINGLE-FAMILY ONLY: § 193-53A permits single-family dwellings plus public and semipublic buildings and grounds; there is no two-family, no townhouse and no accessory dwelling unit. Special permit uses are public utility structures, institutional/religious/cultural uses, professional offices and home occupations carried out in conjunction with a residential use, funeral homes, day-care centres, windmills, and the § 193-53C(5) legalization of a pre-zoning owner-occupied two-family. The column headed 'Maximum Building Coverage Lot' is genuine building coverage and is stored as 35; the adjacent 'Minimum Green Space' column requires 30% of the lot to stay green and is NOT the complement of the coverage figure — 35% building plus 30% green leaves 35% for driveway, walks and patio, so the two constraints bind independently and a scheme can pass one and fail the other. SCHEDULE NOTE ** ADDS A PLACEMENT RULE THAT IS EASY TO MISS: at least half of the required green space must be located IN THE FRONT YARD. Public and semipublic uses take a much larger lot in the same district (20,000 sf, 100 ft width, 50 ft front, 30 ft rear, 15/30 side, 25% coverage); the recorded row is the single-family one. Accessory buildings take 5 ft rear and 5 ft side, with a sliding separation rule by size (10 ft for accessory buildings of 64 sf or less, 12 ft above 64 sf and under 121 sf, 15 ft at 121 sf and above). Schedule I-a separately sets a MINIMUM GROUND FLOOR AREA of 1,000 sf for a one-story dwelling, 900 sf for a story-and-a-half and 800 sf for a two-story — an inverse floor-area requirement rather than a cap, and the strictest of the three districts. | 0.1607 ac | 25 / 5 / 20 ft | 35 ft | No |
| R-1-48 Residential District — 4,800 sf (0.11 acres) minimum lot area with 40 ft of lot width, front yard 20 ft, rear yard 15 ft, side yard 5 ft where the dwelling is two-story and 4 ft where it is one-story, maximum building height 35 ft, maximum building coverage 40% and a minimum green space of 30%. THE DENSEST SINGLE-FAMILY MINIMUM IN THE MONROE DATASET at just over a tenth of an acre — for comparison the Village of Webster's smallest is 9,600 sf and Scottsville's is 6,000 sf, so an R-1-48 lot is half the size of anything else in the county's villages. Uses are identical to R-1-70 (§ 193-53 governs both districts jointly): single-family dwellings and public/semipublic buildings by right, with the same special-permit set including the § 193-53C(5) pre-zoning two-family legalization; no two-family by right, no townhouse, no accessory dwelling unit. Schedule I gives '2-story: 5' and '1-story: 4' and schedule note 2 confirms the figure applies to BOTH side yards, so a single-story house owes 4 ft per side and a two-story owes 5 ft per side — there is no separate combined-total requirement the way R-1-70 has one. Adding a second story to an existing one-story house therefore increases its required side yard and can put a lawfully built dwelling out of compliance; check the as-built side yard before assuming a second story is available. The recorded 5 ft is the two-story case. Coverage of 40% and green space of 30% are independent constraints (see the R-1-70 label), and at least half the green space must be in the front yard. Accessory buildings take 3 ft rear and 3 ft side here, tighter than R-1-70's 5 ft. Schedule I-a sets a minimum ground floor area of 750 sf one-story, 720 sf story-and-a-half and 624 sf two-story. | 0.1102 ac | 20 / 5 / 15 ft | 35 ft | No |
| TR Townhouse Residential District — the recorded figures are the SINGLE- AND TWO-FAMILY row: 4,800 sf (0.11 acres) with 40 ft of lot width, front yard 20 ft, rear yard 15 ft, side yard 5 ft two-story or 4 ft one-story, maximum building height 35 ft, maximum building coverage 45% and a minimum green space of 20%. Townhouses and multifamily dwellings are sized at 2,500 SF PER DWELLING UNIT on an 80 ft minimum width, with a maximum building height of 50 FT and maximum building coverage of 50% — so an acre supports roughly 17 units and the binding constraint is the per-unit area, not any lot minimum. Sizing a TR scheme off the 4,800 sf figure understates it by an order of magnitude. THE TOWNHOUSE YARDS ARE FORMULAS, NOT FIXED NUMBERS, and both are 'whichever is greater' rules keyed to building height: the front yard is 30 FT OR THE BUILDING HEIGHT, and each side yard is 15 FT OR HALF THE BUILDING HEIGHT, with the rear a flat 15 ft. At the 50 ft height cap that means a 50 ft front yard and 25 ft side yards — height is paid for in land here exactly as it is in the Village of Webster's RM. PERMISSION LEVELS DIFFER WITHIN THE DISTRICT AND THE DISTINCTION MATTERS: § 193-55A permits TOWNHOUSES AND TOWNHOUSE DEVELOPMENTS BY RIGHT (along with anything permitted in R-1-70/R-1-48), while § 193-55C(2) makes APARTMENT HOUSES AND MULTIFAMILY DWELLINGS SPECIAL-PERMIT uses — the asterisk in Schedule I marks this. A townhouse scheme is as-of-right subject to § 193-42 site plan review; an apartment building is discretionary. TR IS EFFECTIVELY A MAP-AMENDMENT DISTRICT: § 193-55E(2) contemplates land being REZONED to TR and sets a one-acre minimum tract for that rezoning, so on most parcels the real first step is a rezoning application rather than a building permit — check the zoning map before assuming a parcel is already TR. § 193-55E also sets minimum living space per unit (studio 500 sf, one bedroom 600 sf, two bedrooms 800 sf, three bedrooms 950 sf), requires buildings in a multi-building complex to stand at least the height of the lower building apart, keeps a 6 ft open strip around every building, and sets a courtyard width of 2 ft per 1 ft of height. There is no accessory dwelling unit here or anywhere in the jurisdiction. | 0.1102 ac | 20 / 5 / 15 ft | 35 ft | No |
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 RG&E 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. EAST ROCHESTER HAS NO SHORT-TERM RENTAL LAW BUT IT DOES HAVE A GENERAL RENTAL PERMIT REGIME, AND THE TWO FACTS PULL IN OPPOSITE DIRECTIONS — WHICH IS WHY THIS IS RECORDED 'unknown' RATHER THAN 'prohibited' OR 'regulated'. THE ZONING SIDE IS SILENT: Chapter 193 has no short-term rental, tourist home, bed-and-breakfast, rooming house, boardinghouse, hotel or motel use anywhere in R-1-70, R-1-48 or TR, and none appears in the Article 'Regulations Applicable to All Districts' (guid 10126569) either. The residential lists are closed ('The following uses shall be permitted'), which on the Scottsville reading would make an unlisted transient use barred. This is the Gates Ch. 148 / Mendon Ch. 208 / Village of Pittsford Ch. 154 pattern and it is live and recently amended — adopted 2-13-1995 by L.L. No. 3-1995 and AMENDED 6-12-2025 BY L.L. NO. 1-2025 at both § 144-4 and § 144-8. § 144-4 makes it unlawful for any owner to 'establish, maintain, use, let, lease, rent or suffer or permit the occupancy and use' of a dwelling unit without a permit. § 144-2 defines RENTAL OCCUPANCY as 'the occupancy or use of a dwelling unit by one or more persons as a home or residence under an arrangement whereby the occupant or occupants thereof pay rent' — WITH NO MINIMUM TERM AND NO DURATION TEST ANYWHERE IN THE CHAPTER, so nothing in the text excludes a short stay. § 144-3A scopes it to all rental dwelling units in the Town/Village EXCEPT one at premises where the owner resides under the same tax account number — so an owner-occupied hosted arrangement is outside the permit requirement entirely while an unhosted whole-house rental is inside it. THE DECISIVE CLAUSE CUTS AGAINST READING CH. 144 AS PERMISSION: § 144-3A applies the permit requirement 'WHETHER OR NOT THE USE AND OCCUPANCY THEREOF SHALL BE PERMITTED UNDER THE CURRENTLY APPLICABLE USE REGULATIONS FOR THE ZONING DISTRICT'. Chapter 144 therefore regulates rentals without authorising them — holding a rental permit does not make a use zoning-compliant, and it cannot be cited as evidence that a short-term rental is allowed. THE OPERATIVE TERMS IF A PERMIT IS REQUIRED: permits run THREE YEARS from issuance, or expire 30 days after sale and transfer of the property (§ 144-8, as amended 2025); the Code Enforcement Officer keeps a public register (§ 144-9); § 144-10 adds on-site parking criteria; § 144-11 authorises periodic inspections on consent and notice, with § 144-12 authorising a search warrant application if consent is refused; § 144-13 allows revocation, tied to a 'public nuisance violation' list that reaches Penal Law assault, stolen-property, controlled-substance, marihuana and public-order offences. SO THE PRACTICAL ANSWER FOR AN OPERATOR IS: a hosted rental at your own residence needs no Ch. 144 permit; any other rental does; and whether a SHORT-TERM one is a permitted zoning use at all is unresolved on the text and must be confirmed with the Building Inspector before underwriting it. 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. Town/Village Hall (585) 586-3553, 317 Main Street Suite 2000. Separate question from whether you can build the unit.
- Building dept(585) 586-3553
Sizing up a specific parcel in Town/Village of East Rochester?
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 Town/Village of East Rochester runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Town/Village of East Rochester.
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 · Brockport (Village) · Churchville (Village) · Fairport (Village) · Hilton (Village) · Honeoye Falls (Village) · Pittsford (Village) · Scottsville (Village) · Spencerport (Village) · Webster (Village)
More on Town/Village of East Rochester: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Town/Village of East Rochester: common questions
How much does it cost to build an ADU in Town/Village of East Rochester, NY?
An 800 sq ft accessory dwelling unit in Town/Village of East Rochester 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 Town/Village of East Rochester?
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 Town/Village of East Rochester?
Town/Village of East Rochester has 3 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (585) 586-3553 before you spend money on design.
Can I rent an ADU in Town/Village of East Rochester short term?
No local short-term-rental law on record - which is not the same as permission for Town/Village of East Rochester. 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 Town/Village of East Rochester vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-14; verify with the building department at (585) 586-3553 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).