Parma · ADU cost
What it costs to build an ADU in Parma, NY
An 800 sq ft accessory dwelling unit in Parma 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 Parma maps 8 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 Parma
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 Parma 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 |
|---|---|---|---|---|
| Agricultural Residential (AR) — the Town's agricultural district: 1 ACRE MINIMUM FOR NON-AGRICULTURAL USE (the code states the minimum this way, as a lot area 'for non-agricultural use', so a working farm parcel is not sized by it), 100 ft of lot width, 20% maximum lot coverage, 35 ft height, and the DEEPEST SETBACKS IN THE TOWN — 75 ft primary street yard, 50 ft side and 75 ft rear. Those setbacks, not the acre, are what bind a house on a normal AR lot: 75 ft front plus 75 ft rear consumes 150 ft of depth before any building, and 50 ft on each side consumes 100 ft of a 100 ft minimum width, so a lot built exactly to the district minimum has NO conforming building envelope at all and needs either more width or a variance. Corner lots take a SECONDARY street yard of 75 ft as well. Accessory structures sit 25 ft from rear and side lines. Purpose is active farmland, fallow land, woodland and wetland with low-density residential that supports agricultural operations. Farmworker housing anywhere in the Town takes AR's front, side and rear setbacks regardless of the district it sits in (§ 165-36). Accessory apartment permitted by special use permit under § 165-23. | 1 ac | 75 / 50 / 75 ft | 35 ft | Special permit |
| Rural Residential (RR) — 1 ACRE, 100 ft of lot width, 20% coverage, 35 ft height, with 60 ft primary street yard, 15 ft side and 50 ft rear, and accessory structures 15 ft from rear and side. SEWER IS THE DEFINING CONSTRAINT AND THE CODE SAYS SO IN THE PURPOSE CLAUSE: RR covers areas with 'limited opportunities for infrastructure connections including public sewers,' so an RR parcel should be assumed to need on-site septic until the county parcel layer's SEWERTYPE field says otherwise, and the acre minimum is doing sanitary work as much as density work. The purpose clause also directs that residential development SHOULD USE CLUSTER DEVELOPMENT to preserve rural character, retain open space and conserve natural resources — Town Law § 278 clustering is the expected form here rather than the exception, which means the per-lot acre is negotiable in a cluster layout while the overall yield is not. Same 1-acre minimum as AR but with far shallower side and front yards (15 ft versus 50 ft side), so RR is materially more buildable than AR on an identically sized lot. Accessory apartment permitted by special use permit under § 165-23. | 1 ac | 60 / 15 / 50 ft | 35 ft | Special permit |
| Neighborhood Residential (NR) — the suburban district: 20,000 sf (0.46 acre), 100 ft of lot width, 20% coverage, 35 ft height, 40 ft primary street yard, 10 ft side, 25 ft rear, accessory structures 10 ft from rear and side. A primary street-facing entrance is REQUIRED here rather than merely encouraged as in AR and RR — Parma's newer code carries form standards alongside the dimensional ones, and the entrance requirement is a real design constraint on a garage-forward plan. The 20% coverage cap on a 20,000 sf lot allows 4,000 sf of building footprint, so coverage is not the binding constraint on a typical single-family house here; lot width and the 40 ft front yard are. Accessory apartment permitted by special use permit under § 165-23. | 0.4591 ac | 40 / 10 / 25 ft | 35 ft | Special permit |
| Multifamily Residential (MR) — 10,000 sf, 75 ft of lot width, 30% coverage, 35 ft height, 30 ft primary street yard, 15 ft side, 15 ft rear, accessory structures 10 ft. MR IS THE ONLY DISTRICT IN PARMA WHERE MULTI-UNIT HOUSING AND TOWNHOMES ARE AVAILABLE AT ALL, both by SPECIAL PERMIT under § 165-55, and it is also the only district permitting a two-unit home by right outside N-MU. The recorded 10,000 sf is the lot minimum, NOT a per-unit figure, and the code sets no units-per-acre cap in this section — so yield on an MR parcel is set by § 165-55's supplemental standards, the 30% coverage cap and the 35 ft height together rather than by a density number, and it must be worked from those three rather than assumed. NOTE A TYPOGRAPHICAL HAZARD IN THE SOURCE: the code renders this figure as '10.000 sf' with a decimal point where a comma belongs, and the Waterfront district does the same with '5.000 sf'. Read them as 10,000 and 5,000; a naive parse would produce 10 sf. Accessory apartment permitted by special use permit under § 165-23. | 0.2296 ac | 30 / 15 / 15 ft | 35 ft | Special permit |
| Waterfront Residential (WR) — the Lake Ontario shoreline district and by far the smallest lot in Parma: 5,000 sf, 50 ft of lot width, 30% coverage, 35 ft height, with the tightest yards in the Town at 20 ft primary street, 10 ft side, 10 ft rear and accessory structures 5 ft from rear and side. This is a 9x smaller minimum lot than AR and RR on the same 35 ft height, and it reflects the pre-existing narrow shoreline lot pattern along the lake rather than a policy of density. A primary street-facing entrance is required. THE DISTRICT CODE IS WR, NOT WF — see the note in `source` about a third-party site that gets this wrong. Note that WR's 20 ft front and 10 ft side yards make it the one Parma district where a conforming house fits comfortably on the district's own minimum lot. Accessory apartment permitted by special use permit under § 165-23. | 0.1148 ac | 20 / 10 / 10 ft | 35 ft | Special permit |
| Corridor Mixed-Use (C-MU) — 20,000 sf, 75 ft of lot width, 50% coverage, 35 ft height, 30 ft primary street yard, 15 ft side, 15 ft rear, accessory structures 10 ft. The 50% coverage is double the residential districts' 20% and is the main dimensional concession the mixed-use districts get; the 35 ft height is NOT relaxed, so C-MU is a low-rise commercial corridor by design and there is no district in Parma of any kind that permits a building over 35 ft. C-MU carries form requirements the residential districts do not: building placement and orientation under § 165-59, building composition under § 165-60, landscaping under § 165-63 and parking location under § 165-65C, plus a required primary street-facing entrance. NO ACCESSORY APARTMENT IS AVAILABLE HERE — the § 165-13 use table shows a dash for C-MU — and unlike N-MU, C-MU does not permit single-unit or two-unit homes either, so it is the more strictly commercial of the two mixed-use districts. A funeral home is available by special permit in C-MU and N-MU only (§ 165-37). | 0.4591 ac | 30 / 15 / 15 ft | 35 ft | No |
| Neighborhood Mixed-Use (N-MU) — 15,000 sf, 50 ft of lot width, 50% coverage, 35 ft height, 30 ft primary street yard, 10 ft side, 15 ft rear, accessory structures 10 ft. N-MU IS THE MOST HOUSING-PERMISSIVE DISTRICT IN PARMA ON A BY-RIGHT BASIS: the § 165-13 use table gives it BOTH single-unit and two-unit homes by right, where the two-unit home is by right only in MR among the residential districts — so a neighbourhood mixed-use parcel can take a duplex without a special permit while the surrounding NR cannot. Home business is available by special permit. It has the smallest lot-width minimum of the two mixed-use districts at 50 ft, matching WR. NO ACCESSORY APARTMENT is available (a dash in the use table), so the second unit arrives as a principal two-unit home rather than as an accessory one — the same structural point found in Chili, and it means aduPermitted:not-permitted understates what can actually be built here. N-MU additionally carries HOURS-OF-OPERATION limits under § 165-64: no business use in N-MU may be open to the public outside the hours that section sets, a restriction that does not apply in C-MU, where hours are set through site plan review instead. | 0.3444 ac | 30 / 10 / 15 ft | 35 ft | No |
| Light Industrial (LI) — 20,000 sf, 100 ft of lot width, 50% coverage, 35 ft height, and deep yards at 75 ft primary street, 25 ft side and 50 ft rear, with accessory structures 25 ft from rear and side. LI SHARES AR'S 75 FT STREET SETBACK, which is unusual for an industrial district and means an LI parcel loses substantial depth to the front yard before any building or loading area; combined with the 50 ft rear yard that is 125 ft of depth committed. The 35 ft height cap applies here as everywhere in Parma, so this district cannot accommodate high-bay industrial or warehouse forms that need 40 ft or more of clear height without a variance — a material constraint for any modern distribution or light-manufacturing use, and the single most decision-relevant fact about industrial land in this town. A primary street-facing entrance is required and landscaping runs under § 165-63. No dwellings and no accessory apartment are available in LI. Outdoor storage is separately capped at 15% of the entire lot area and is not allowed in the front yard. | 0.4591 ac | 75 / 25 / 50 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 allowed with local rules. Short-term rentals are REGULATED INSIDE THE ZONING CHAPTER ITSELF, not by a separate rental-licensing law — § 165-54 Short-term Rental (STR) sits in Article IV Use Standards, which is why a search of the Town Code's other chapters finds nothing. The rules are unusually tight and they bind on the OPERATOR, not just the building. An STR must be OWNER-OPERATED. No more than ONE non-resident of the premises may be engaged as an employee of the operation, so the model of a remote owner with a local cleaning-and-turnover crew does not fit. The unit is capped at FOUR GUEST ROOMS, with no more than four guest rooms sharing a single bathroom. Maximum length of stay for any guest is 30 CONSECUTIVE DAYS, which is the conventional line and unlike the Town of Gates' unusually long three-month definition elsewhere in this county. Guest parking may NOT be located in the front yard, and the Planning Board approves the location and screening of all required parking — so an STR approval in Parma runs through the Planning Board on the parking question even where the use itself is allowed. Because the STR standards are use standards rather than a district permission, read them together with the § 165-13 use table for the specific district: STR is not listed as a permitted or special-permitted use in every district, and the use table governs whether the use is available at all before § 165-54 governs how it operates. New York State's 2025 statewide registry (Ch. 99 of the Laws of 2025) applies on top. Confirm current practice with the Building Department at (585) 392-9449. Separate question from whether you can build the unit.
- Building dept(585) 392-9449
Sizing up a specific parcel in Parma?
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 Parma runs $204–268/sq ft, about $370k–480k at 1,800 sq ft , plus roughly $886 for a conforming lot. See what it costs to build a house in Parma.
ADU cost in nearby towns
All Monroe County towns: Rochester (City) · Brighton · Chili · Clarkson · Gates · Greece · Hamlin · Henrietta · Irondequoit · Mendon · Ogden · 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 Parma: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Parma: common questions
How much does it cost to build an ADU in Parma, NY?
An 800 sq ft accessory dwelling unit in Town of Parma 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 Parma?
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 Parma?
Town of Parma has 8 districts. 5 districts allow ADUs with a special-use permit, 3 do not. Check the specific address with the free ADU checker or confirm with the building department at (585) 392-9449 before you spend money on design.
Can I rent an ADU in Parma short term?
Short-term rentals allowed with local rules for Town of Parma. 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 Parma vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-12; verify with the building department at (585) 392-9449 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).