Gates · ADU cost
What it costs to build an ADU in Gates, NY
An 800 sq ft accessory dwelling unit in Gates 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 Gates maps 5 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
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ADU cost by size in Gates
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 Gates 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 Residence | 0.34 ac | 35 / 10 / 30 ft | 35 ft | Occupancy restricted |
| Single-Family Residence | 0.25 ac | 35 / 8 / 30 ft | 35 ft | Occupancy restricted |
| Single-Family Residence | 0.18 ac | 35 / 7 / 30 ft | 35 ft | Occupancy restricted |
| Multiple Residence District | 5 ac | 35 / 40 / 40 ft | 35 ft | No |
| Townhouse Residence District | 10 ac | 35 / 40 / 20 ft | 35 ft | No |
Single-Family Residence - The front setback depends on the class of street the lot fronts under § 190-36, not on the district, and a corner lot has two front yards, each set by the class of street that side fronts on.
- Minimum floor area is 1,750 sq ft for any dwelling other than a single-family house of one floor level; the 1,400 sq ft shown is the one-floor case.
- The side yard is 10% of the required lot width at the front setback line, capped at 10 ft and never under 6 ft, so it does not grow on an oversized lot.
- The width may be increased by up to 10% of the lot depth with the depth reduced, if the minimum area and front setback are kept and depth to width stays within 2.5 to 1.
- Two-family structures were repealed as a conditional use here on 4 May 1981, so a second dwelling unit cannot be added.
- Accessory structures are limited to 15 ft in height.
Single-Family Residence - The front setback depends on the class of street the lot fronts under § 190-36, not on the district, and a corner lot has two front yards, each set by the class of street that side fronts on.
- Minimum floor area is 1,375 sq ft for any dwelling other than a single-family house of one floor level; the 1,100 sq ft shown is the one-floor case.
- The side yard is 10% of the required lot width at the front setback line, capped at 10 ft and never under 6 ft, so it does not grow on an oversized lot.
- The width may be increased by up to 10% of the lot depth with the depth reduced, if the minimum area and front setback are kept and depth to width stays within 2.5 to 1.
- Two-family structures were repealed as a conditional use here on 4 May 1981, so a second dwelling unit cannot be added.
- Accessory structures are limited to 15 ft in height.
Single-Family Residence - The front setback depends on the class of street the lot fronts under § 190-36, not on the district, and a corner lot has two front yards, each set by the class of street that side fronts on.
- Minimum floor area is 1,250 sq ft for any dwelling other than a single-family house of one floor level; the 1,000 sq ft shown is the one-floor case.
- The side yard is 10% of the required lot width at the front setback line, capped at 10 ft and never under 6 ft, so it does not grow on an oversized lot.
- The width may be increased by up to 10% of the lot depth with the depth reduced, if the minimum area and front setback are kept and depth to width stays within 2.5 to 1.
- Two-family structures were repealed as a conditional use here on 4 May 1981, so a second dwelling unit cannot be added.
- Accessory structures are limited to 15 ft in height.
Multiple Residence District - Land is zoned MR only by rezoning on application for a specific proposal. No multiple-residence structure may contain more than eight dwelling units, and no unit's floor area may be below grade.
- A two-family or other two-unit structure is permitted outright and takes a different lot: 15,000 square feet, since the five-acre minimum applies to multiple-residence complexes only.
- Duplex floor areas follow the R-1-15 figures, 1,400 sq ft for a one-floor-level dwelling and 1,750 sq ft for all other types, rather than the apartment schedule.
- The front setback depends on the class of street the lot fronts, under § 190-36, and any buffer § 190-34A requires is added on top of the 40 ft side and rear setback.
- Each multiple residence needs at least 400 sq ft of common open space for recreation.
- Minimum floor area is 450 sq ft for an efficiency, 600 for a one-bedroom, 800 for a two-bedroom and 950 for a three-bedroom, excluding halls, foyers and basement utility areas.
- Site plan approval is required, and accessory structures are limited to 15 ft in height.
Townhouse Residence District - Land is zoned TH only by rezoning on application for a specific proposal. Each dwelling unit needs three paved parking spaces, one fully enclosed and covered, and none of them may sit in the front setback.
- The individual townhouse lot is a separate row beneath the ten-acre tract: 2,000 sq ft of area, 20 ft of width at the main building line and 100 ft of depth, all variable by the Planning Board.
- A single-family dwelling answers to R-1-11 instead: 11,000 sq ft on 80 ft of width, an 8 ft side yard on the 10% of width formula, a 30 ft rear yard, 25% coverage, 1,375 sq ft for other types.
- Density may not exceed five dwelling units per gross acre overall or 10 dwelling units on any one acre.
- The 40 ft side figure is measured between clusters; a separate 40 ft applies from property lines, plus the buffer § 190-34A and B require from other districts.
- The front setback depends on the class of street the lot fronts, under § 190-36, and the rear figure is for a main building; an accessory structure needs 5 ft.
- No part of the habitable floor area may be below grade, and the Planning Board may vary the rear setback, the individual lot dimensions and the parking requirement.
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. Renting a home short term requires a short-term rental property permit under § 148-7, and short term means occupancy by someone other than the owner for less than three months, which takes in month-to-month tenancies. Separate question from whether you can build the unit.
- Zoning codeecode360.com/12242998
- Building dept(585) 429-8242
Sizing up a specific parcel in Gates?
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 Gates runs $204–268/sq ft, about $370k–480k at 1,800 sq ft , plus roughly $3,215 for a conforming lot. See what it costs to build a house in Gates.
ADU cost in nearby towns
All Monroe County towns: Rochester (City) · Brighton · Chili · Clarkson · Greece · Hamlin · Henrietta · Irondequoit · Mendon · Ogden · Parma · Penfield · Perinton · Pittsford · Riga · Rush · Sweden · Webster · Wheatland · East Rochester (Village) · Brockport (Village) · Churchville (Village) · Fairport (Village) · Hilton (Village) · Honeoye Falls (Village) · Pittsford (Village) · Scottsville (Village) · Spencerport (Village) · Webster (Village)
More on Gates: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Gates: common questions
How much does it cost to build an ADU in Gates, NY?
An 800 sq ft accessory dwelling unit in Town of Gates 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 Gates?
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 Gates?
Town of Gates has 5 districts. 3 districts allow ADUs with occupancy restrictions, 2 do not. Check the specific address with the free ADU checker or confirm with the building department at (585) 429-8242 before you spend money on design.
Can I rent an ADU in Gates short term?
Short-term rentals allowed with local rules for Town of Gates. 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 Gates vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-11; verify with the building department at (585) 429-8242 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.