Aurora · ADU cost
What it costs to build an ADU in Aurora, NY
An 800 sq ft accessory dwelling unit in Aurora 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 Aurora maps 8 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 Aurora
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Erie 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 Aurora 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 |
|---|---|---|---|---|
| R1 Single-Family Residential District | 0.75 ac | 75 / 20 / 50 ft | 35 ft | Occupancy restricted |
| R2 Residential District | 0.75 ac | 50 / 12.5 / 40 ft | 35 ft | Occupancy restricted |
| R3 Residential District | 0.75 ac | 50 / 12.5 / 40 ft | 35 ft | Occupancy restricted |
| Rural Residential District | 0.75 ac | 75 / 20 / 50 ft | 35 ft | Occupancy restricted |
| Agriculture District | 3 ac | 75 / 40 / 100 ft | 35 ft | Occupancy restricted |
| Commercial District | 0.75 ac | 50 / 30 / 45 ft | 35 ft | Occupancy restricted |
| Commercial District | 0.75 ac | 50 / 30 / 45 ft | 35 ft | Occupancy restricted |
| Commercial District | 0.75 ac | 50 / 40 / 60 ft | 35 ft | No |
Rural Residential District - The 75 ft front yard is contextual as well as fixed: where a fifth or more of the lots in the same block, on the same side of the street and within 1,000 ft are already built on, the average setback of those buildings becomes the building line, never under 45 ft.
- On a corner lot the secondary street takes 45 ft
- Frontage along the right-of-way must be 125 ft as well as the lot width, and the right-of-way itself is excluded from the lot area
- An accessory building stands back by its own mean height and never less than ten feet, may not sit in the front yard, and its footprint may not exceed a quarter of the required rear yard
- Height is a maximum mean, measured to the average between eaves and ridge on a pitched roof, so a steep gable may stand higher than 35 ft at the ridge
- Six chickens or other poultry per acre are allowed, no roosters, housed in the rear yard at least 25 ft from any lot line; large domestic animals need an acre of undeveloped land each
Agriculture District - Farm structures other than farm dwellings have no height limit at all where an agricultural exemption exists through the Town Tax Assessor; everything else stops at two and a half storeys and 35 ft, and an accessory building at two storeys and 20 ft.
- A multiple-family dwelling adds 4,000 sq ft for each unit beyond the first
- A dwelling group of two or more units on one lot needs a Town Board special use permit, and each dwelling must sit so that the lot could later be split with both halves conforming
- The right-of-way is excluded from the lot area
- Height is a maximum mean, measured to the average between eaves and ridge on a pitched roof, so a steep gable may stand higher than 35 ft at the ridge
Commercial District - A commercial building here is capped at 5,000 square feet, and drive-through facilities are not permitted in this district at all.
- The side and rear yards are height-linked with a floor: each must equal at least the mean height of the building, and never less than the figure shown
- A residential use in a commercial district takes 20 ft at the side and 30 ft at the rear instead
- The 50 ft front yard applies to buildings; parking must additionally leave 20 ft of green space between it and the street right-of-way, and on a corner lot the secondary street takes 30 ft
- The coverage figure is a total: no more than half the lot may be used for structures and impermeable surfaces together, and no individual building may exceed 30% of the lot area
- Franchise architecture is not permitted, a landscape plan is required with every site plan application, and site plan review under Chapter 95 applies to every commercial use
- Height is a maximum mean, measured to the average between eaves and ridge on a pitched roof, so a steep gable may stand higher than 35 ft at the ridge
Commercial District - A commercial building here is capped at 20,000 square feet. A use permitted by right is one of the C-1 by-right uses at no more than 10,000 sq ft; anything larger needs a special use permit, as does a drive-through facility.
- The side and rear yards are height-linked with a floor: each must equal at least the mean height of the building, and never less than the figure shown
- A residential use in a commercial district takes 20 ft at the side and 30 ft at the rear instead
- The 50 ft front yard applies to buildings; parking must additionally leave 20 ft of green space between it and the street right-of-way, and on a corner lot the secondary street takes 30 ft
- The coverage figure is a total: no more than half the lot may be used for structures and impermeable surfaces together, and no individual building may exceed 30% of the lot area
- Franchise architecture is not permitted, a landscape plan is required with every site plan application, and site plan review under Chapter 95 applies to every commercial use
- Height is a maximum mean, measured to the average between eaves and ridge on a pitched roof, so a steep gable may stand higher than 35 ft at the ridge
Commercial District - A commercial building here is capped at 30,000 square feet, and a drive-through facility needs a special use permit.
- The side and rear yards are height-linked with a floor: each must equal at least the mean height of the building, and never less than the figure shown
- A residential use in a commercial district takes 20 ft at the side and 30 ft at the rear instead
- The 50 ft front yard applies to buildings; parking must additionally leave 20 ft of green space between it and the street right-of-way, and on a corner lot the secondary street takes 30 ft
- The coverage figure is a total: no more than half the lot may be used for structures and impermeable surfaces together, and no individual building may exceed 30% of the lot area
- Franchise architecture is not permitted, a landscape plan is required with every site plan application, and site plan review under Chapter 95 applies to every commercial use
- Height is a maximum mean, measured to the average between eaves and ridge on a pitched roof, so a steep gable may stand higher than 35 ft at the ridge
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 National Grid 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. Short-term rental is an expressly named permitted use, but the code defines it as an owner-occupied residence in which a dwelling unit is let, so an unhosted, investor-owned whole-house rental does not meet the definition. Separate question from whether you can build the unit.
- Zoning codeecode360.com/39725487
- Building dept(716) 652-7591
Sizing up a specific parcel in Aurora?
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Building a full house instead?
A standard-finish house in Aurora runs $204–268/sq ft, about $370k–480k at 1,800 sq ft , plus roughly $8,415 for a conforming lot. See what it costs to build a house in Aurora.
ADU cost in nearby towns
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More on Aurora: Can you build an ADU here? · Zoning for new construction · Erie County build cost
ADU cost in Aurora: common questions
How much does it cost to build an ADU in Aurora, NY?
An 800 sq ft accessory dwelling unit in Town of Aurora 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 Aurora?
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 Aurora?
Town of Aurora has 8 districts. 7 districts allow ADUs with occupancy restrictions, 1 does not. Check the specific address with the free ADU checker or confirm with the building department at (716) 652-7591 before you spend money on design.
Can I rent an ADU in Aurora short term?
Short-term rentals allowed for Town of Aurora. 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 Erie 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 Aurora vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-09-10; verify with the building department at (716) 652-7591 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.