Ogden · ADU cost

What it costs to build an ADU in Ogden, NY

An 800 sq ft accessory dwelling unit in Ogden 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 Ogden maps 10 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 Ogden

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.

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.

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 Ogden 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.

Size limits on record in Ogden

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 Ogden:

• Rural Agricultural (RA) — 1 ACRE MINIMUM AND, UNUSUALLY, A 3 ACRE MAXIMUM: the code caps lot size as well as setting a floor, expressly to stop farmland being consumed by large residential lots, and the maximum may rise above three acres only where the Monroe County Health Department requires more room for an on-lot sewage system, in quarter-acre increments. 150 ft of lot width, 250 ft of lot depth, 20% maximum building coverage, front 60 ft, side 25 ft for all buildings, rear 50 ft for residential and 30 ft for agricultural, principal height 35 ft (2 1/2 storeys), accessory 15 ft (one storey). THE BINDING CONSTRAINT IS NOT THE LOT MINIMUM — IT IS A SLIDING-SCALE SUBDIVISION CAP KEYED TO THE PARENT TRACT. § 300-25 limits the maximum number of lots that may be created from a parcel by the acres of contiguous land held in single and separate ownership (the 'parent tract') AS IT STOOD ON 16 MARCH 1981, or the date the land was first zoned RA if later: at least 2 but under 6 acres yields 1 lot, 6 to 30 yields 2, 30 to 80 yields 3, 80 to 130 yields 4, 130 to 180 yields 5, 180 to 230 yields 6, and 230 to 280 yields 7. A 200-acre RA farm therefore yields SIX lots, not the roughly 200 that dividing by the one-acre minimum would suggest — an error of more than 30x. The scale attaches to the 1981 parent tract, so lots already split off since then count against the allowance and the current deed acreage is NOT the input; establishing the 1981 configuration is the first step in underwriting any RA parcel. Minimum habitable floor area is 1,200 sf for a one-storey dwelling (§ 300-58). Farm buildings have no minimum interior distance requirement. No in-law apartment is available in RA.The apartment may not exceed 750 sq ft
• Rural Residential (RR) — WATER AVAILABILITY MOVES THE MINIMUM LOT BY 2.5x: 87,120 sf (2 acres) with 200 ft of width at the building line WHERE PUBLIC WATER IS AVAILABLE, rising to FIVE ACRES with 300 ft of width where it is not. The recorded figures are the public-water case. Front setback is 100 ft from a public road; principal height 35 ft (2 1/2 storeys), accessory 15 ft. sideSetback and rearSetback are therefore null by design; what actually separates buildings here is a SPACING RULE — the minimum distance between principal structures on adjacent lots is the height of the taller building plus 30 feet, which on a 35 ft house means 65 ft between structures. CLUSTER DENSITY IS NOT THE LOT MINIMUM: under Town Law § 278 with public water the minimum lot drops to ONE acre and the width to 160 ft, but the overall development is computed at THREE ACRES PER LOT, rising to FIVE ACRES PER LOT for land regulated as floodplain, wetland, steep slope or otherwise environmentally limited. So clustering buys smaller lots, not more of them, and constrained land cuts yield by a further 40%. In cluster developments the minimum front setback remains 100 ft. RR sets no lot coverage. Minimum habitable floor area is 1,600 sf for a one-storey dwelling — the largest house-size floor in the town alongside RT. No in-law apartment is available in RR.The apartment may not exceed 750 sq ft
• Residential Transition (RT) — the district for land where, in the code's own words, lack of public utilities and environmental conditions require larger lots. DENSITY AND MINIMUM LOT SIZE ARE DIFFERENT NUMBERS HERE AND BOTH MATTER. Density is one lot per 1/2 ACRE with both public sewer and water, one lot per ONE acre with water or sewer only, and one lot per THREE acres with neither. The dimensional chart separately sets the MINIMUM LOT at 1 acre / 1 acre / 3 acres across the same three service levels. The half-acre density with full utilities is therefore only reachable by clustering under Town Law § 278 — the code states plainly that public sewer and water are required to reduce lot size below one acre — so on a fully serviced RT parcel a conventional subdivision yields half the units a density calculation would suggest, and the § 278 cluster is what closes the gap. Recorded figures are the serviced case: 1 acre, 150 ft of width at the setback line (and at the street line, and for corner lots), front 60 ft, side 15 ft, rear 30 ft, principal height 35 ft (2 1/2 storeys), accessory 15 ft. Without either service the lot goes to 3 acres and the width to 200 ft while the setbacks stay identical. RT sets NO lot coverage, so maxLotCoverage is null by design. Minimum habitable floor area is 1,600 sf for a one-storey dwelling. No in-law apartment is available in RT.The apartment may not exceed 750 sq ft
• Single-Family Residential (R-1) — 30,000 sf, or 40,000 sf WITHOUT public water and sewer; 150 ft of lot width, or 200 ft without those services; 200 ft of lot depth; front 60 ft; side 15 ft for principal buildings, 15 ft for accessory structures and 5 ft for sheds; rear 30 ft for principal buildings, 15 ft for accessory structures and 5 ft for sheds; principal height 35 ft (2 1/2 storeys), accessory structures 24 ft, sheds 15 ft. The recorded figures are the serviced case. MAXIMUM COVERAGE IS 20% BY ALL BUILDINGS, WITH A SEPARATE AND MUCH TIGHTER ACCESSORY CAP: accessory structures may cover no more than 1% of the lot AND may not exceed 5,000 sf of total floor area per parcel REGARDLESS OF LOT SIZE. On the 30,000 sf minimum lot that 1% is just 300 sf, so a detached garage or barn is constrained by the accessory percentage long before the 20% overall figure binds — this is the constraint to quote on any R-1 outbuilding question. NON-RESIDENTIAL USES IN R-1 TAKE AN ENTIRELY DIFFERENT AND MUCH LARGER ENVELOPE, which is easy to misread as the residential one: 400 ft of lot depth, 250 ft of lot width, 125 ft front setback and 50 ft side and rear setbacks. R-1 IS THE ONLY DISTRICT IN OGDEN WITH AN IN-LAW APARTMENT, available as a conditional use from the Zoning Board of Appeals and restricted to the owners of record and their blood relatives — see `aduNotes`, because that occupancy restriction means it produces no market rent. Minimum habitable floor area is 1,500 sf for a one-storey dwelling.The apartment may not exceed 750 sq ft
• Two-Family Residential (R-2) — 40,000 sf, or 62,500 sf WITHOUT public water and sewer; 200 ft of lot width, or 250 ft without; 200 ft of lot depth, or 250 ft without; front 60 ft; side and rear 30 ft for principal buildings and 5 ft for accessory structures; principal height 35 ft (2 1/2 storeys), accessory 15 ft (one storey). Recorded figures are the serviced case, and note the unserviced penalty here is the steepest in the town at 56% more land. Maximum building coverage is 30%, ten points more than R-1, with accessory structures capped at 1% PER LIVING UNIT and no accessory structure exceeding 400 sf of floor area except on farms — a much tighter accessory cap than R-1's 5,000 sf. R-2 IS THE REAL ROUTE TO A SECOND INCOME UNIT IN OGDEN: it permits a genuine two-family dwelling as a PRINCIPAL use, whereas the only accessory unit in the town is R-1's in-law apartment, whose occupancy is restricted to blood relatives and which therefore cannot be rented. Minimum habitable floor area is 1,000 sf PER LIVING UNIT for a one-storey dwelling, so a two-family on the district minimum must deliver 2,000 sf of habitable area.The apartment may not exceed 750 sq ft
• Multiple-Family Residential (MFR) — THERE IS NO MINIMUM LOT AREA IN THIS DISTRICT, AND THAT NULL IS THE CODE, NOT A GAP: § 300-30 regulates apartment houses by DENSITY instead, requiring a minimum of 3,500 SQUARE FEET OF LOT AREA IN THE PROJECT AREA FOR EACH LIVING UNIT. Yield is therefore project area divided by 3,500 sf, which is roughly 12.4 units per acre, and any figure derived from a district lot minimum would be meaningless. What the code does fix is the SHAPE of the parcel: no apartment house may sit on a lot with a depth of less than 250 ft or a WIDTH OF LESS THAN 280 FT — the widest lot-width requirement in Ogden, wider than Light Industrial's 250 ft — so a narrow parcel is disqualified from MFR development no matter how much total area it has. Setbacks are correspondingly deep: front 100 ft, side 65 ft, rear 65 ft, with a minimum 30 ft between buildings. TOWNHOUSES ARE REGULATED SEPARATELY IN THE SAME DISTRICT (§ 300-30D): maximum 2 1/2 storeys or 35 ft, accessory structures 15 ft or one storey, minimum 960 sf of habitable area per townhouse, minimum 18 ft width per townhouse, NO MORE THAN EIGHT TOWNHOUSES PER BUILDING OR DWELLING GROUP, and no exterior wall may continue on the same plane for more than 75 ft without an offset of at least 4 ft. No room with more than four feet of its vertical height below grade may be used for living purposes, which rules out a conventional walk-out basement bedroom. MFR sets no lot coverage figure. No in-law apartment is available.The apartment may not exceed 750 sq ft
• Restricted Business (RB) — ROAD CLASS DOUBLES THE MINIMUM LOT IN THIS DISTRICT, which is the trap to watch: 40,000 sf on internal or local access roads but 80,000 sf on ARTERIAL OR COLLECTOR STREETS, with lot width likewise 200 ft rising to 300 ft. Recorded figures are the internal/local case, the county convention. Lot depth 200 ft. Front setback is 85 ft on internal or local roads and 160 ft on arterial or collector streets, and on a collector or arterial the town may increase it further to accommodate future widening or a frontage road — so an RB parcel fronting a main highway can lose more than twice the depth to the front yard, and the setback is not even fixed. On parcels of five acres or less the minimum setback FOR PARKING LOTS ONLY drops to 25 ft. Side setback 25 ft, rising to 50 ft where adjacent to a residential district or parcel; rear setback 30 ft, likewise rising to 50 ft adjacent to residential. TWO COVERAGE CAPS APPLY AND maxLotCoverage RECORDS THE BUILDING ONE: 35% maximum by buildings and accessory uses, and a separate 70% maximum by buildings, structures, parking areas and all other paved surfaces. On top of that, not less than 30% OF THE LOT must be set aside for seeding, planting, retention of tree cover or other landscaping and used for no other purpose — a hard green-space floor that, with the 70% impervious cap, is what really sizes an RB site plan. Maximum height 35 ft and not more than 2 1/2 storeys; accessory structures 15 ft or one storey.The apartment may not exceed 750 sq ft
• Neighborhood Commercial (NC) — 40,000 sf with 200 ft of lot width and 200 ft of lot depth, and unlike RB the lot area does NOT double on an arterial road, though the front setback still does: 85 ft on internal or local access roads and 160 ft on arterial or collector streets, with the same power to increase it for future widening or a frontage road, and the same reduction to 25 ft for parking lots only on parcels of five acres or less. Side setback 25 ft, rising to 50 ft where adjacent to a residential district or parcel; rear setback 30 ft, likewise 50 ft adjacent to residential. Coverage is the same two-cap structure as RB — 35% by buildings and accessory uses (recorded), 70% by buildings, structures, parking and all other paved surfaces — plus the same requirement that at least 30% of the lot be devoted to seeding, planting and retention of tree cover and used for no other purpose. Maximum building height is 2 1/2 STOREYS OR 35 FEET, WHICHEVER IS THE LESSER, so a tall two-and-a-half-storey design can be cut off before it reaches 35 ft; accessory structures 15 ft or one storey.The apartment may not exceed 750 sq ft
• General Commercial (GC) — ONE ACRE minimum with 200 ft of lot width on internal, local, arterial and collector roads alike, and 200 ft of lot depth. Front setback 60 ft on internal or local access roads and 100 ft on arterial or collector streets, reduced to 25 ft for parking lots only on parcels of five acres or less. SIDE SETBACK: NONE REQUIRED, except where the Planning Board prescribes one, and sideSetback is recorded as 0 rather than null because zero is the stated standard — a GC building may sit on its side line. Rear setback 30 ft, rising to 60 ft where adjacent to ANY residential district, in addition to any buffer area required by § 300-52. Coverage runs the same two caps as RB and NC: 35% by buildings and structures (recorded) and 70% by buildings, structures, parking areas and all other impervious areas. Maximum height 2 1/2 storeys or 35 ft, whichever is the lesser. GC IS THE ONLY DISTRICT IN OGDEN WHERE A SMOKE SHOP MAY OPERATE — L.L. No. 5-2024 added a new Chapter 245 restricting smoke shops to GC under § 300-33, subject to separation distances measured property line to property line. That law adds a chapter and changes no dimension in Ch. 300.The apartment may not exceed 750 sq ft
• Light Industrial (LI) — 62,500 sf with 250 ft of lot width and 250 ft of lot depth. Front setback 60 ft on internal or subdivision streets and 100 ft on existing arterial or collector highways, reduced to 25 ft for parking lots only on parcels of five acres or less; side 30 ft; rear 50 ft. Coverage is 35% by buildings and structures (recorded) and 70% by buildings, structures and parking areas. LI IS THE ONLY DISTRICT IN OGDEN THAT EXCEEDS 35 FEET AND THE ONLY ONE WHOSE HEIGHT WAS RECENTLY RAISED: maximum building height is 45 FEET, amended 11-28-2018 by L.L. No. 1-2018 and again 4-26-2023 by L.L. No. 4-2023. Every other district in the town — residential, business and commercial — is held to 35 ft, so LI is the only place in Ogden that can accommodate a modern high-bay warehouse, distribution or light-manufacturing form without a variance, and that 45 ft cap is the single most decision-relevant industrial fact in the town. Off-street parking follows the Schedule in § 300-80, and the Planning Board may increase or decrease those standards for specific uses during site plan review.The apartment may not exceed 750 sq ft

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 Ogden's Ch. 300 Zoning, and no separate rental-licensing chapter was found in the Town Code — the only 'transient' hit in the whole 150,942-character zoning chapter is in the noise regulations, exempting transient noise from moving sources such as automobiles, trucks and railroads. Ogden regulates lodging only through the conventional use list; there is no tourist home, no bed-and-breakfast standard and no STR permit. ABSENCE IS NOT PERMISSION: Ch. 300 defines permitted uses as a closed list per district, so a short-term rental in an Ogden house may be unpermitted as an unlisted use even though no section names it. Note the contrast with the Town of Gates in the same county, which regulates STRs through a separate Ch. 148 Rental Properties law with a permit and a three-month threshold — a search of a Monroe town's ZONING chapter alone is not sufficient to conclude there is no STR regime, and the Ogden Town Code's other chapters should be swept once more before this is treated as settled. 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) 617-6195. Separate question from whether you can build the unit.
• Building dept(585) 617-6195

Building a full house instead?

A standard-finish house in Ogden runs $204–268/sq ft, about $370k–480k at 1,800 sq ft , plus roughly $2,295 for a conforming lot. See what it costs to build a house in Ogden.

ADU cost in nearby towns

All Monroe County towns: Rochester (City) · Brighton · Chili · Clarkson · Gates · Greece · Hamlin · Henrietta · Irondequoit · Mendon · 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 Ogden: Can you build an ADU here? · Zoning for new construction · Monroe County build cost

ADU cost in Ogden: common questions

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 Ogden 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) 617-6195 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).