Greece · ADU cost
What it costs to build an ADU in Greece, NY
An 800 sq ft accessory dwelling unit in Greece 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 town 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 of Greece maps 12 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 Greece
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 Greece 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 |
|---|---|---|---|---|
| Single-Family Residential (R1-44) | 1.0101 ac | 70 / 20 / 70 ft | — | Occupancy restricted |
| Single-Family Residential (R1-18) | 0.4132 ac | 50 / 10 / 50 ft | — | Occupancy restricted |
| Single-Family Residential (R1-10) | 0.2296 ac | 25 / 6 / 40 ft | — | Occupancy restricted |
| Single-Family Residential — Established Neighborhood (R1-E) | — | 25 / 6 / - ft | — | Occupancy restricted |
| Multiple-Family Residential (RM) | — | 100 / 50 / 50 ft | — | No |
| Senior Citizen Residential (RS) | — | 100 / 50 / 50 ft | — | No |
| Professional Business (BP) | 0.2755 ac | 30 / 15 / 15 ft | 40 ft | No |
| Restricted Business (BR) | 0.3444 ac | 30 / 15 / 15 ft | — | No |
| General Business (BG) | 0.4591 ac | 30 / 20 / 20 ft | — | No |
| Flexible Office-Industrial (FOI) | 1 ac | 100 / 0 / 0 ft | — | No |
| Light Industrial (IL) | 3 ac | 100 / 25 / 25 ft | — | No |
| General Industrial (IG) | 5 ac | 100 / 25 / 25 ft | — | No |
Size limits on record in Greece
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 Greece:
- Single-Family Residential (R1-44)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Single-Family Residential (R1-18)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Single-Family Residential (R1-10)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Single-Family Residential — Established Neighborhood (R1-E)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Multiple-Family Residential (RM)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Senior Citizen Residential (RS)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Professional Business (BP)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Restricted Business (BR)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- General Business (BG)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Flexible Office-Industrial (FOI)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- Light Industrial (IL)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
- General Industrial (IG)Greece does NOT have a general accessory-dwelling-unit allowance in its residential districts. The residential path is ONE IN-LAW APARTMENT per one-family dwelling, defined at § 211-5C as a dwelling unit for "a relative by marriage" of the resident family, and it is occupancy-restricted: the owner must sign a NOTARIZED AFFIDAVIT that the occupant is an in-law of the resident family, and the apartment may not exceed 30% of the dwelling's gross floor area (excluding attached garages) OR 600 square feet, WHICHEVER IS LESS. Note that the phrase "accessory dwelling units" DOES appear in Ch. 211, but it means something else entirely — upper-floor apartments accessory to a commercial principal use in a business district, barred below the second floor and permitted only in structures existing as of the local law. Do not read that provision as a residential ADU right. Read against Ch. 211 (§ 211-5C definition and the in-law apartment standards) 2026-08-17. Verify with the building department at (585) 723-2443.
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 allowed with local rules. Short-term rentals require a Town permit under § 162A-7 of Chapter 162A, Rental Properties — the Rental Properties Law of the Town of Greece, adopted 4-15-2014 by L.L. No. 2-2014 and amended in its entirety 7-15-2014 by L.L. No. 4-2014. The chapter carries a general rental property permit at § 162A-4 and a distinct short-term rental property permit at § 162A-7, with enforcement presumptions at § 162A-8. The requirement sits outside Zoning Chapter 211, which is why a zoning-only search misses it. New York State's 2025 short-term rental registry (Ch. 99 of the Laws of 2025) separately requires every host statewide to register the unit regardless of local law. Confirm with Town of Greece at (585) 723-2443 before listing. Separate question from whether you can build the unit.
- Building dept(585) 723-2443
Sizing up a specific parcel in Greece?
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 Greece runs $204–268/sq ft, about $370k–480k at 1,800 sq ft , plus roughly $4,642 for a conforming lot. See what it costs to build a house in Greece.
ADU cost in nearby towns
All Monroe County towns: Rochester (City) · Brighton · Chili · Clarkson · Gates · 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) · Spencerport (Village) · Webster (Village)
More on Greece: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Greece: common questions
How much does it cost to build an ADU in Greece, NY?
An 800 sq ft accessory dwelling unit in Town of Greece 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 Greece?
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 Greece?
Town of Greece has 12 districts. 8 districts prohibit ADUs, 4 allow them with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (585) 723-2443 before you spend money on design.
Can I rent an ADU in Greece short term?
Short-term rentals allowed with local rules for Town of Greece. 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 of Greece vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-07; verify with the building department at (585) 723-2443 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).