Brockport · ADU cost
What it costs to build an ADU in Brockport, NY
An 800 sq ft accessory dwelling unit in Brockport 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 Brockport 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 Brockport
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 Brockport 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 |
|---|---|---|---|---|
| O Residential Use District — Brockport's only residential district, so every house in the village is answered from this one row. 10,000 sf (0.23 acres) with 85 ft of lot width, rear yard 30 ft, two side yards of not less than 10 ft each, maximum height 35 ft and maximum lot coverage 30% counting ONE-FAMILY DWELLINGS AND THEIR ACCESSORY STRUCTURES TOGETHER, so a detached garage consumes the house's allowance. § 58-9E also provides that not more than one dwelling shall be erected, placed or occupied on one lot. THE FRONT YARD IS 30 FT OR THE NEIGHBOURHOOD AVERAGE, WHICHEVER IS GREATER, AND THE AVERAGE IS DEFINED PRECISELY: 'the front setback in any event shall not be less than the average front setback established by existing residences on the same street, to be determined by an average of the setbacks within 200 FEET of said lot'. On any built-up Brockport street the neighbours set the building line and the recorded 30 ft is a floor, not the requirement. This is the same family of contextual override as Greece's neighbourhood-average rule and Hilton's most-common-setback-on-the-block provision, but Brockport's is the most precisely specified of the three. NARROW PRE-EXISTING LOTS GET A PROPORTIONAL AND ASYMMETRIC SIDE-YARD RULE, which is unusual and easy to miss: where a lot lawfully had a width of less than 85 ft at the time the chapter was enacted, the side yards are modified in proportion to the lot width so that ONE SIDE YARD IS NOT LESS THAN 4 FT AND THE OTHER NOT LESS THAN 11 FT. So a legacy narrow lot does not simply lose both 10 ft yards evenly — it gets a deliberately lopsided envelope totalling 15 ft, and the 4 ft side is the tightest residential side yard recorded in this county. CORNER LOTS OWE 30 FT along the side lot line adjacent to the side street, running the full depth from front lot line to rear lot line — equal to the front and rear yards, so a corner lot is constrained on three sides. THE BOARD OF APPEALS MAY VARY THE YARDS where established yards within 200 ft of the premises differ from the chapter's requirements, which makes the whole yard schedule contextual on an established street rather than fixed. A bed-and-breakfast is available only as a home occupation on a ZBA special conditional use permit with owner-occupancy, a nine-guest cap and a fifteen-day stay limit — see `strNotes`. | 0.2296 ac | 30 / 10 / 30 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 rentalsShort-term rentals restricted. BROCKPORT HAS NO SHORT-TERM RENTAL PROVISION BY THAT NAME, BUT ITS BED-AND-BREAKFAST REGIME IS THE MOST DETAILED AND MOST RESTRICTIVE LODGING CONTROL FOUND IN MONROE COUNTY, AND IT FUNCTIONS AS THE VILLAGE'S ANSWER TO PAID OVERNIGHT STAYS. § 58-9 permits a bed-and-breakfast in the O Residential Use District only 'as a home occupation as per § 58-9A(5)', subject to a SPECIAL CONDITIONAL USE PERMIT from the Zoning Board of Appeals and a long list of conditions, of which five are commercially decisive. (1) THE APPLICANT MUST BE THE OWNER OF THE PREMISES AND A FULL-TIME RESIDENT — an investor-owned whole-house rental is therefore impossible in this district. (2) NO MORE THAN NINE GUESTS PER NIGHT, and the ZBA may fix a lower number. (3) NO GUEST MAY STAY MORE THAN 15 DAYS ON ANY ONE VISIT. (4) A minimum of three off-street parking spaces is required, and no permit may issue if an off-street parking variance was granted for the property within the previous five years. (5) THE PERMIT DOES NOT RUN WITH THE LAND — any new owner must apply to the Zoning Board of Appeals afresh to continue the use, the same non-transferability that Mendon's Ch. 208 STR permit carries and a material diligence point on any Brockport acquisition premised on lodging income. A further condition provides that the residence operating as a bed-and-breakfast SHALL NOT CONTAIN AN ACCESSORY APARTMENT, so the two uses are mutually exclusive. THE COMBINED EFFECT — OWNER-OCCUPANCY, A NINE-GUEST CAP, A FIFTEEN-DAY LIMIT AND A ZBA PERMIT THAT DIES ON SALE — IS THAT AN ORDINARY WHOLE-HOUSE SHORT-TERM RENTAL IS NOT ACHIEVABLE IN BROCKPORT'S RESIDENTIAL DISTRICT, and strStatus is recorded 'restricted' on that basis rather than 'unknown'. A sweep of all 56 chapters of the Village Code found no separate rental-licensing chapter. 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 Code Enforcement at (585) 637-5300 ext. 114. Separate question from whether you can build the unit.
- Building dept(585) 637-5300 ext. 114
Sizing up a specific parcel in Brockport?
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 Brockport runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Brockport.
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) · Churchville (Village) · Fairport (Village) · Hilton (Village) · Honeoye Falls (Village) · Pittsford (Village) · Scottsville (Village) · Spencerport (Village) · Webster (Village)
More on Brockport: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Brockport: common questions
How much does it cost to build an ADU in Brockport, NY?
An 800 sq ft accessory dwelling unit in Village of Brockport 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 Brockport?
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 Brockport?
Village of Brockport has 1 district. The only district prohibits ADUs. Check the specific address with the free ADU checker or confirm with the building department at (585) 637-5300 ext. 114 before you spend money on design.
Can I rent an ADU in Brockport short term?
Short-term rentals restricted for Village of Brockport. 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 Brockport 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) 637-5300 ext. 114 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).