Sweden · ADU cost
What it costs to build an ADU in Sweden, NY
An 800 sq ft accessory dwelling unit in Sweden 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 Sweden maps 4 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 Sweden
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 Sweden 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 |
|---|---|---|---|---|
| One-Family Residential, no sewer and/or water (R1-2) — 80,000 sf (1.84 acres) with 200 ft of width measured AT THE FRONT LINE OF THE HOUSE (not at the street), 200 ft of depth and only 60 ft of road frontage, which makes this a flag-lot-friendly district: a lot may neck down to 60 ft at the road provided it opens to 200 ft where the house sits. Front setback 75 ft, rear 40 ft, side 10 ft, maximum height 36 ft. § 175-15 names this district 'One-Family Residential District, no sewer and/or water' — the unserviced district is the DEFAULT residential zone of the town and the S districts are separately mapped, so this is not a sewer-conditional reading of one district the way Perinton's classes are. THE 80,000 SF HEADLINE IS THE MIDDLE OF A FOUR-STEP LADDER KEYED TO THE SEPTIC SYSTEM AND WATER SUPPLY, AND THE SPREAD IS 5.4x. § 175-36D(2) sets: 40,000 sf with 150 ft of width where the lot has PUBLIC WATER and an in-ground or modified raised fill system; 80,000 sf base; 150,000 sf with 260 ft of width where an ABOVEGROUND modified raised fill system is used (mineral deposits or shallow bedrock); and FIVE ACRES with 260 ft of width where a FULL raised fill system is required. Road frontage stays 60 ft at every step. THE 40,000 SF STEP IS THE COMMON CASE, NOT AN EXCEPTION — a 1,919-parcel residential sample of Sweden from the Monroe County parcel layer returned 1,312 on public water against 605 private, so roughly 68% of residential parcels already have the water half of that test and the binding question is the soil, not the pipe. Underwriting an R1-2 parcel therefore starts with a percolation and depth-to-bedrock answer, not with the district minimum. LOT AREA IS NET, NOT GROSS, AND THIS IS THE SECOND YIELD TRAP: § 175-36D(2)(d) requires lot areas to be EXCLUSIVE OF designated wetlands AND THEIR ONE-HUNDRED-FOOT BUFFERS, highway rights-of-way, reserved strips, and the land containing the driveway on a flag lot. A hundred-foot buffer around a small wetland removes far more area than the wetland itself, and on a flag lot the entire access neck is deducted, so gross deed acreage divided by 80,000 sf overstates yield on any constrained parcel. Minimum building size is 1,000 sf for a ranch, 710 sf for a one-and-one-half-storey, split-level or raised ranch, and 576 sf for a two-storey. Note that the septic system carries its own setbacks distinct from the building's: an aboveground modified raised fill system on a 150,000 sf lot needs 75 ft to the sides and 50 ft front and rear, and on a 40,000 sf lot 25 ft to every property line, with front leach field setbacks measured from the point at which the lot attains its required width at the front line of the house. | 1.8365 ac | 75 / 10 / 40 ft | 36 ft | No |
| One-Family Residential within a sanitary sewer district (R1-2S) — 15,000 sf (0.34 acres) with 100 ft of width at the front line of the house, 150 ft of depth and 60 ft of road frontage. Front setback 50 ft, RISING TO 75 FT ON AN ARTERIAL HIGHWAY; rear 40 ft; side 10 ft; maximum height 36 ft. THE 'S' IS A MAPPED SEWER DISTRICT, NOT A CONDITIONAL ALTERNATIVE — § 175-15 defines this district as 'One-Family Residential District within a sanitary sewer district', so a parcel is either in it or in R1-2 by location on the Zoning Map, and the answer for a given parcel comes from the map rather than from asking whether that lot happens to be connected. The practical consequence is the largest single dimensional fact in the town: THE SAME ONE-FAMILY HOUSE NEEDS 15,000 SF HERE AND 80,000 SF IN R1-2, a 5.3x difference in land per lot driven purely by which district the parcel sits in. Sewer availability is genuinely split across the town — a 1,919-parcel residential sample from the Monroe County parcel layer returned 1,113 on private septic against 802 on public sewer, so the unserviced R1-2 case is the majority and this district is the minority, concentrated around the Village of Brockport. None of the R1 districts state a maximum lot coverage, so the null here is the code rather than a gap; the envelope is controlled by the setbacks and the 36 ft height alone. Minimum building size is the same town-wide floor as R1-2: 1,000 sf ranch, 710 sf one-and-one-half-storey or split-level or raised ranch, 576 sf two-storey. Unlike R1-2 this district states no septic-system ladder and no net-area deduction clause, because neither applies to a sewered lot. | 0.3444 ac | 50 / 10 / 40 ft | 36 ft | No |
| One-Family Residential within a sanitary sewer district (R1-3S) — 10,200 sf (0.23 acres) with 85 ft of width at the front line of the house, 120 ft of depth and 50 ft of road frontage. This is the SMALLEST minimum lot in the Town of Sweden and the town's densest one-family district. Front setback 40 ft, RISING TO 75 FT ON AN ARTERIAL HIGHWAY, and note the additional rule that ALL PROPERTY LINES ABUTTING A STREET MUST MEET THE FRONT SETBACK — so a corner lot owes 40 ft on both frontages rather than a front and a side, which on an 85 ft wide lot is the constraint that actually shapes the buildable envelope. Rear 40 ft; side 10 ft; maximum height 36 ft. THE DEPTH FIGURE IS THE ONLY FLEXIBLE DIMENSION IN THE TOWN: § 175-38D(1)(c) permits the 120 ft depth to be reduced BY UP TO 10% (to 108 ft) provided the minimum square-foot lot area is still maintained, which is a trade of depth for width rather than a reduction in area. Like R1-2S this is a mapped sewer district under § 175-15, not a conditional reading, and like every R1 district it states no maximum lot coverage, so that null is deliberate. Minimum building size is the town-wide floor: 1,000 sf ranch, 710 sf one-and-one-half-storey, split-level or raised ranch, 576 sf two-storey — worth noting against the small lot, since a 1,000 sf ranch footprint on a 10,200 sf lot is already about 10% coverage before a garage or driveway. | 0.2342 ac | 40 / 10 / 40 ft | 36 ft | No |
| Multiple Residence (MR-1) — the town's only multi-unit district, and the only route to a second dwelling unit anywhere in Sweden. Permits multiple dwellings, town homes, patio homes, condominiums and ZERO LOT-LINE DUPLEXES AND QUADPLEXES as principal uses BY RIGHT, with no special permit named in § 175-39A. MR-1 STATES NO MINIMUM LOT AREA AT ALL AND minLotSize IS THEREFORE NULL BY DESIGN, NOT MISSING: § 175-39B(2) is headed 'Required lot area' but gives only a 200 ft frontage and a 200 ft depth, so the district is governed by shape plus density rather than by an area floor. YIELD COMES FROM THE DENSITY CAP AND THE COVERAGE CAP TOGETHER: no more than 12 DWELLING UNITS PER ACRE, and lot coverage no more than 50%. Setbacks are front 20 ft, side 20 ft, rear 50 ft — the front and side are the most permissive in the town by a wide margin (against 40-75 ft fronts in the R1 districts) while the rear is the most restrictive, and a minimum distance of 20 ft is required between buildings on the same site. Maximum height 36 ft, the same as every residential district here. A THIRD CONSTRAINT BINDS ALONGSIDE THE 50% COVERAGE AND IS EASY TO MISS: § 175-39B(5) requires AT LEAST 25% OF THE TOTAL LOT AREA TO REMAIN OPEN AND UNUSED, and while that open area may count landscaping, stormwater retention or detention, underground utilities, screening and fencing, it MAY NOT be paved or used for parking, storage, buildings or accessory buildings. Because parking is excluded from the open area but is not counted in the 50% building coverage either, the real site plan is a three-way split between building, parking and protected open space, and the 25% floor will often bind before the 50% cap on a surface-parked scheme. Appropriate landscaping is required throughout the district. | — | 20 / 20 / 50 ft | 36 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 rentalsNo local short-term-rental law on record - which is not the same as permission. NO short-term rental provision exists anywhere in the Town of Sweden Code. Ch. 175 Zoning was searched in full across all twelve articles and contains no short-term rental, tourist home, bed-and-breakfast or transient-occupancy standard; the only 'rental' hits in the chapter are inside the ADULT BOOKSTORE and ADULT VIDEO STORE definitions in § 175-7, which concern the sale or rental of printed and video material and have nothing to do with lodging. THE ZONING CHAPTER ALONE IS NOT A SUFFICIENT CHECK IN THIS COUNTY and it was not relied on: the Town of Gates regulates STRs from a SEPARATE Ch. 148 Rental Properties law, so all 64 chapters of the Sweden Code were enumerated from the eCode360 table of contents and swept for a rental, lodging, licensing or registration chapter. There is none. The closest chapters are Ch. 141 Property Maintenance and Ch. 169 Vacant Building Registry, neither of which reaches short-term rental. The Building Department's own published permit list corroborates this — it offers building, plumbing, pool/spa, sign, home occupation and vacant-building-registration forms and no short-term rental permit. ABSENCE IS NOT PERMISSION: Ch. 175 states permitted principal uses as a closed list per district, so a short-term rental in a Sweden dwelling may be unpermitted as an unlisted use even though no section names it. 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 the Building Department at (585) 637-8684. Separate question from whether you can build the unit.
- Building dept(585) 637-8684
Sizing up a specific parcel in Sweden?
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 Sweden runs $204–268/sq ft, about $370k–480k at 1,800 sq ft . See what it costs to build a house in Sweden.
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 · 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 Sweden: Can you build an ADU here? · Zoning for new construction · Monroe County build cost
ADU cost in Sweden: common questions
How much does it cost to build an ADU in Sweden, NY?
An 800 sq ft accessory dwelling unit in Town of Sweden 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 Sweden?
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 Sweden?
Town of Sweden has 4 districts. All districts prohibit ADUs. Check the specific address with the free ADU checker or confirm with the building department at (585) 637-8684 before you spend money on design.
Can I rent an ADU in Sweden short term?
No local short-term-rental law on record - which is not the same as permission for Town of Sweden. 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 Sweden 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) 637-8684 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).