Fairport · ADU cost
What it costs to build an ADU in Fairport, NY
An 800 sq ft accessory dwelling unit in Fairport 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 Fairport 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 Fairport
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 Fairport 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 |
|---|---|---|---|---|
| Residential Low Density (RLD) — 15,000 sf (0.34 acres) with 85 ft of lot width, side setback 15 ft, rear setback 50 ft, maximum building height 30 ft and A MAXIMUM BUILDING COVERAGE OF JUST 15%, by a wide margin the most restrictive coverage figure recorded anywhere in Monroe County. On the 15,000 sf minimum that allows a 2,250 sf building footprint, so the coverage cap — not the setbacks — is the binding constraint on any substantial house here, and a large single-storey design will hit it before it hits the yards. THE 50 FT REAR SETBACK EQUALS THE FRONT and is the deepest in the village, so RLD lots hold a large private core. THE FRONT SETBACK IS 50 FT 'OR SEE § 551-75', a contextual override — on a built-up street the established building line may govern instead of the 50 ft figure, in the same family as Hilton's most-common-setback-on-the-block rule and Greece's neighbourhood-average override. Do not quote 50 ft as fixed without checking § 551-75. ACCESSORY BUILDINGS ARE REGULATED SEPARATELY AND MUCH MORE TIGHTLY IN THE YARDS BUT NOT IN THE FRONT: 5 ft side and 5 ft rear setbacks against the principal building's 15 and 50, but a full 50 ft front setback, the same as the principal building. The district's purpose statement expressly contemplates accessory dwelling units — see `aduNotes`. Height is stated in feet only, 30 ft, with no storey limit, which is lower than the 35 ft that is standard across almost every other Monroe jurisdiction. | 0.3444 ac | 50 / 15 / 50 ft | 30 ft | As of right |
| Residential Neighborhood (RN) — 7,500 sf (0.17 acres) with 50 ft of lot width, front setback 30 ft, side 10 ft, rear 30 ft, maximum building height 30 ft and maximum building coverage 35%. This is Fairport's ordinary village-fabric district and it is HALF the lot of RLD at MORE THAN DOUBLE the coverage allowance, which is a far sharper step than the lot sizes alone suggest: 35% of 7,500 sf is 2,625 sf of footprint against RLD's 2,250 sf on twice the land. A house in RN can therefore be physically LARGER in footprint than one in the low-density district. THE DISTRICT IS DEFINED AS A MIX OF SINGLE-FAMILY AND TWO-FAMILY DWELLINGS — § 551-11A says so in its purpose statement — so a two-family is part of the district's character rather than an exception, and the same statement expressly contemplates accessory dwelling units alongside it. See `aduNotes`. THE FRONT SETBACK IS 30 FT 'OR SEE § 551-75', a contextual override — on an established street the prevailing building line may govern instead. Accessory buildings take 5 ft side and 5 ft rear setbacks but a full 30 ft front setback, matching the principal building. Height is 30 ft with no storey limit stated. | 0.1722 ac | 30 / 10 / 30 ft | 30 ft | As of right |
| Residential Transitional Neighborhood (RTN) — 4,000 sf (0.09 acres), the smallest residential lot in Monroe County, with maximum building coverage 55% and a height standard stated as 3 STORIES / 42 FEET, the only residential district in the county to exceed the near-universal 35 ft. Front setback 20 ft, side 10 ft, rear 15 ft. The recorded 25 is the townhouse figure because the townhouse is plainly the form this district exists to deliver — a 4,000 sf lot at 25 ft of width is a fee-simple rowhouse parcel, and no other Monroe jurisdiction provides for one. Sizing a detached house here requires the 50 ft figure instead. THE FRONT SETBACK IS 20 FT 'OR SEE § 551-75', the same contextual override that applies in RLD and RN. Accessory buildings take 5 ft side and 5 ft rear setbacks and a 20 ft front, matching the principal building. Note that the height row is formatted differently from the other districts — it appears under a separate 'Height Standards (Maximum Stories/Feet)' heading rather than as a lot-standards row — so a parser keyed to the RLD and RN table shape will miss it. | 0.0918 ac | 20 / 10 / 15 ft | 42 ft | As of right |
Size limits on record in Fairport
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 Fairport:
- Residential Low Density (RLD) — 15,000 sf (0.34 acres) with 85 ft of lot width, side setback 15 ft, rear setback 50 ft, maximum building height 30 ft and A MAXIMUM BUILDING COVERAGE OF JUST 15%, by a wide margin the most restrictive coverage figure recorded anywhere in Monroe County. On the 15,000 sf minimum that allows a 2,250 sf building footprint, so the coverage cap — not the setbacks — is the binding constraint on any substantial house here, and a large single-storey design will hit it before it hits the yards. THE 50 FT REAR SETBACK EQUALS THE FRONT and is the deepest in the village, so RLD lots hold a large private core. THE FRONT SETBACK IS 50 FT 'OR SEE § 551-75', a contextual override — on a built-up street the established building line may govern instead of the 50 ft figure, in the same family as Hilton's most-common-setback-on-the-block rule and Greece's neighbourhood-average override. Do not quote 50 ft as fixed without checking § 551-75. ACCESSORY BUILDINGS ARE REGULATED SEPARATELY AND MUCH MORE TIGHTLY IN THE YARDS BUT NOT IN THE FRONT: 5 ft side and 5 ft rear setbacks against the principal building's 15 and 50, but a full 50 ft front setback, the same as the principal building. The district's purpose statement expressly contemplates accessory dwelling units — see `aduNotes`. Height is stated in feet only, 30 ft, with no storey limit, which is lower than the 35 ft that is standard across almost every other Monroe jurisdiction.ONE BEDROOM maximum and 650 SQ FT maximum; one ADU per lot per single-family dwelling
- Residential Neighborhood (RN) — 7,500 sf (0.17 acres) with 50 ft of lot width, front setback 30 ft, side 10 ft, rear 30 ft, maximum building height 30 ft and maximum building coverage 35%. This is Fairport's ordinary village-fabric district and it is HALF the lot of RLD at MORE THAN DOUBLE the coverage allowance, which is a far sharper step than the lot sizes alone suggest: 35% of 7,500 sf is 2,625 sf of footprint against RLD's 2,250 sf on twice the land. A house in RN can therefore be physically LARGER in footprint than one in the low-density district. THE DISTRICT IS DEFINED AS A MIX OF SINGLE-FAMILY AND TWO-FAMILY DWELLINGS — § 551-11A says so in its purpose statement — so a two-family is part of the district's character rather than an exception, and the same statement expressly contemplates accessory dwelling units alongside it. See `aduNotes`. THE FRONT SETBACK IS 30 FT 'OR SEE § 551-75', a contextual override — on an established street the prevailing building line may govern instead. Accessory buildings take 5 ft side and 5 ft rear setbacks but a full 30 ft front setback, matching the principal building. Height is 30 ft with no storey limit stated.ONE BEDROOM maximum and 650 SQ FT maximum; one ADU per lot per single-family dwelling
- Residential Transitional Neighborhood (RTN) — 4,000 sf (0.09 acres), the smallest residential lot in Monroe County, with maximum building coverage 55% and a height standard stated as 3 STORIES / 42 FEET, the only residential district in the county to exceed the near-universal 35 ft. Front setback 20 ft, side 10 ft, rear 15 ft. The recorded 25 is the townhouse figure because the townhouse is plainly the form this district exists to deliver — a 4,000 sf lot at 25 ft of width is a fee-simple rowhouse parcel, and no other Monroe jurisdiction provides for one. Sizing a detached house here requires the 50 ft figure instead. THE FRONT SETBACK IS 20 FT 'OR SEE § 551-75', the same contextual override that applies in RLD and RN. Accessory buildings take 5 ft side and 5 ft rear setbacks and a 20 ft front, matching the principal building. Note that the height row is formatted differently from the other districts — it appears under a separate 'Height Standards (Maximum Stories/Feet)' heading rather than as a lot-standards row — so a parser keyed to the RLD and RN table shape will miss it.ONE BEDROOM maximum and 650 SQ FT maximum; one ADU per lot per single-family dwelling
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-rental status not confirmed. NO SHORT-TERM RENTAL PROVISION APPEARS IN FAIRPORT'S NEW ZONING CHAPTER. A search of Article 4 District Standards for 'short-term rental' returns nothing, and a sweep of all 53 chapters of the Village Code found no standalone rental, lodging, licensing or registration chapter of the Gates Ch. 148 or Mendon Ch. 208 kind. TREAT THIS FINDING AS PROVISIONAL FOR ONE SPECIFIC REASON: Fairport has just replaced its zoning code wholesale (Ch. 551 supersedes Ch. 550, now marked 'Prior Zoning Code (Reserved)'), the chapter carries 'new_releases' markers on its sections indicating very recent publication, and a NYSDEC Environmental Notice Bulletin dated 2026-02-25 records a Village of Fairport 'Code Update' still moving through SEQR review. A village mid-recode is exactly the situation where a use can be added between one reading and the next, and the STR question is the most commonly amended one in this county. RE-CHECK Ch. 551 AND THE VILLAGE BOARD'S AGENDA BEFORE RELYING ON THIS NEGATIVE AFTER 2026. Note also the divergence from the surrounding Town of Perinton, which likewise has no STR provision — but the two codes are independent and a Perinton finding does not transfer, as the Pittsford town-versus-village split in this county demonstrates. 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 Building and Code Enforcement at (585) 421-3207. Separate question from whether you can build the unit.
- Building dept(585) 421-3207
Sizing up a specific parcel in Fairport?
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 Fairport runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Fairport.
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) · Hilton (Village) · Honeoye Falls (Village) · Pittsford (Village) · Scottsville (Village) · Spencerport (Village) · Webster (Village)
More on Fairport: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Fairport: common questions
How much does it cost to build an ADU in Fairport, NY?
An 800 sq ft accessory dwelling unit in Village of Fairport 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 Fairport?
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 Fairport?
Village of Fairport has 3 districts. All districts allow ADUs. Check the specific address with the free ADU checker or confirm with the building department at (585) 421-3207 before you spend money on design.
Can I rent an ADU in Fairport short term?
Short-term-rental status not confirmed for Village of Fairport. 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 Fairport 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) 421-3207 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).