Franklin · ADU cost
What it costs to build an ADU in Franklin, NY
An 800 sq ft accessory dwelling unit in Franklin runs roughly $185k–245k, or about $233–305/sq ft, and that per-square-foot figure sits deliberately above the $191–250/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 Franklin maps 6 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 Franklin
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Delaware County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $309–$404 | $125k–160k |
| 600 sq ft | One bedroom | $258–$338 | $155k–205k |
| 800 sq ft | One bedroom, larger | $233–$305 | $185k–245k |
| 1,000 sq ft | Two bedroom | $218–$285 | $220k–285k |
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–$10 | $7 | — |
| Foundation | $15–$21 | $15 | — |
| Framing | $24–$30 | $24 | — |
| Envelope - roof, siding, windows | $30–$38 | $30 | — |
| Plumbing | $26–$32 | $15 | 55% |
| Electrical | $17–$22 | $12 | 35% |
| HVAC | $21–$27 | $14 | 45% |
| Insulation | $7–$9 | $7 | — |
| Interior finishes | $30–$40 | $26 | 15% |
| Millwork & cabinetry | $17–$26 | $10 | 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 Franklin 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 |
|---|---|---|---|---|
| Rural-I District — THE STATE AND COUNTY HIGHWAY CORRIDOR, defined geographically rather than by map colour: § 404A includes all lands within 500 FEET OF THE CENTER LINE of a State or County highway with DIRECT FRONTAGE on the right-of-way, where the highway is one maintained by the County or State as of the ordinance's effective date and shown on the Zoning Map. Its purpose is to allow a variety of mixed uses appropriate to a high-volume, good-access road. Minimum lot size 1 acre; minimum frontage 250 ft; maximum height 35 ft; side and rear setbacks 20 ft each; maximum lot coverage 25%; maximum lot depth-to-width ratio 4:1, AND FOR EACH INCREMENT IN THAT RATIO THE REQUIRED FRONTAGE EXTENDS BY 50 FT — a shape rule that quietly penalises deep narrow lots twice over. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. THIS DISTRICT IS THE ONE WHERE THAT ASSUMPTION IS LEAST SAFE, because it fronts State and County highways whose rights-of-way are routinely WIDER than 50 ft: on a 66 ft right-of-way the same rule gives about 67 ft from the lot line, and on an 80 ft right-of-way about 60 ft. The recorded 75 is therefore the conservative end. Check the actual right-of-way width before siting. Permitted uses are one one- or two-family dwelling per lot, one mobile home per lot, agricultural practices, forestry management and wildlife management; everything else in Schedule I is a special permit use or prohibited. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district. | 1 ac | 75 / 20 / 20 ft | 35 ft | Occupancy restricted |
| Rural-III District — THE TOWN ROAD CORRIDOR: § 405A includes all lands within 500 FEET OF THE CENTER LINE of a town road with direct frontage on the right-of-way, counting roads maintained by the Town as of the ordinance's effective date BUT EXPRESSLY EXCLUDING SEASONAL USE ROADS — a parcel fronting a seasonal road falls to Rural V and its 5-acre minimum instead, which is a 2-acre difference decided entirely by the road's maintenance status. Purpose: lower-density residential, agriculture and limited commercial. Minimum lot area 3 acres; minimum frontage 300 ft; maximum height 35 ft; side and rear setbacks 25 ft each; maximum lot coverage 20%; maximum lot depth-to-width ratio 4:1. Front setback 75 ft from the road centre line, recorded as 50 ft, being the lot-line equivalent on a 50 ft right-of-way; on a narrower right-of-way the rule binds harder (a 33 ft right-of-way gives about 58.5 ft). READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. Permitted uses and accessory uses are the same list as Rural I. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district. | 3 ac | 50 / 25 / 25 ft | 35 ft | Occupancy restricted |
| Rural-V District — THE BACKLAND DISTRICT AND THE DEFAULT FOR REMOTE PARCELS: § 406A includes all lands NOT within 500 ft of an existing Town, County or State right-of-way, plus all lands fronting on Town "Seasonal Use Only" roads as designated on the Zoning Map. Purpose: only low-density residential development with limited commercial uses. Minimum lot area 5 acres; minimum frontage 350 ft, the largest in the town; maximum height 35 ft; side and rear setbacks 30 ft each; maximum lot depth-to-width ratio 4:1. Front setback 75 ft from the road centre line, recorded as 50 ft on the 50 ft right-of-way basis. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. § 406F(6) reads "Maximum lot coverage: Fifteen per cent (25%)" — the words say fifteen and the numeral in brackets says twenty-five, and they cannot both be right. 15 is recorded on two grounds. First, where words and figures conflict the words conventionally govern. Second, and more persuasively, the town's coverage figures form a clean descending series as the districts get more rural — Hamlet 25%, Rural I 25%, Rural III 20%, Public Water Supply 10% — and 15% is exactly the missing step, while 25% would make the most rural district identical to the least. THE SCHEDULE THAT WOULD SETTLE IT DOES NOT EXIST: the table of contents lists "SCHEDULE II — TABLE OF DIMENSIONAL REGULATIONS" at page 73, but the document ends at page 73 with Schedule I and contains no Schedule II at all. Raise this with the Code Enforcement Officer before relying on either figure; the difference is 10% of a 5-acre lot. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district. | 5 ac | 50 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Hamlet District — THE HAMLET OF TREADWELL specifically, as denoted on the Zoning Map; this is a single named crossroads community rather than a general category, and Franklin's other settlement, the VILLAGE of Franklin, is a separate jurisdiction entirely and not governed by this ordinance. Purpose: to recognise a crossroads community where residential and commercial business uses exist in harmony, providing basic services for the surrounding community and homes for the people who provide them. Minimum lot area ONE-HALF ACRE, the smallest in the town; minimum frontage 100 ft; maximum height 35 ft; side and rear setbacks 20 ft each; maximum lot coverage 25%; maximum depth-to-width ratio 3:1, tighter than the 4:1 used everywhere else. Front setback 55 ft from the road centre line, which on a 50 ft right-of-way resolves to 30 ft from the front lot line — recorded as 30. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. Permitted uses and accessory uses are the same lists as Rural I, so the district's mixed character comes from Schedule I's special permit column rather than from its by-right uses. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district. | 0.5 ac | 30 / 20 / 20 ft | 35 ft | Occupancy restricted |
| Public Water Supply District — THE MOST RESTRICTIVE DISTRICT IN THE TOWN, AND THE ONE MOST LIKELY TO BE MISSED because it is defined by a radius rather than by a mapped block: § 408A includes all lands WITHIN A 500-FOOT RADIUS OF THE PUBLIC WATER SUPPLY WELLS AND SPRINGS for the Village of Franklin and the hamlet of Treadwell. The stated rationale is the wellhead cone of depression — contamination entering groundwater within it is certain to reach the pumping well — so the restrictions are about water, not density. Everything, including a single-family dwelling, is a SPECIAL PERMIT use — one one- or two-family dwelling per lot, one mobile home per lot, agricultural practices, forest management, wildlife management practices, public utilities and facilities, public parks and recreation facilities, and the accessory uses listed for the Rural I district, all only by special permit from the Planning Board. Minimum lot size 10 ACRES, twice Rural V's; minimum frontage 300 ft; maximum height 35 ft; side and rear setbacks 30 ft; maximum lot coverage 10%, the tightest in the town; maximum lot depth-to-width ratio 4:1. NOTE THE FRONT SETBACK IS THE ONE DISTRICT MEASURED FROM THE RIGHT-OF-WAY RATHER THAN THE CENTRE LINE: § 408F(4) states 200 FEET FROM RIGHT-OF-WAY, so 200 is recorded directly with no conversion, and it is by far the deepest front setback in the town. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. | 10 ac | 200 / 30 / 30 ft | 35 ft | Special permit |
| Development Limitations Overlay District — AN OVERLAY, NOT A STANDALONE DISTRICT: § 409D makes minimum lot size, minimum frontage, maximum height, front setback, side and rear setbacks, maximum lot coverage and the depth-to-width ratio ALL "same as the underlying district", which is why every dimensional field here is null. Exactly one thing changes, and it changes yield rather than dimensions. § 409D(1) applies only WHERE THE ORIGINAL PARCEL BEING SUBDIVIDED HAS MORE THAN FIFTY PERCENT of its land area in one or more Development Limitations. Above that threshold the maximum number of lots allowed per acre of the ORIGINAL parcel is 0.44 in Rural I, 0.15 in Rural III and 0.09 in Rural V. Read those as acres per lot and the effect is stark: 2.27 acres per lot in Rural I against a 1-acre minimum, 6.67 acres in Rural III against 3, and 11.1 ACRES PER LOT IN RURAL V AGAINST A 5-ACRE MINIMUM — the overlay more than doubles the land needed per lot in every district. The 50% threshold is what makes Franklin's version less pervasive than Middletown's, whose overlay fires when any two of five limitations exist "to any degree", but it is also all-or-nothing: a parcel at 51% encumbrance takes the full density cap. TRIGGERS: flood hazard areas including those on Flood Hazard Boundary Map No. H 01-10 dated 1988-01-18; freshwater wetlands as defined and protected by the NYS Freshwater Wetlands Act; steep slopes of 15% OR MORE; and high elevation areas of 2,000 FEET OR GREATER — the same 2,000 ft trigger as the Town of Delhi and 500 ft lower than Middletown's. PROCESS: the Code Enforcement Officer screens every zoning permit application for construction in the Flood Hazard Area or within 100 ft of a NYS regulated wetland; no zoning permit issues for construction in the Flood Hazard Area until the Planning Board grants a Special Permit, and none within 100 ft of a regulated wetland until the applicant has NYSDEC approval. Plans must comply with the NYS Wetlands Act and with Local Law No. 1 of 1987, Flood Damage Prevention. THE OVERLAY MAPS ARE ON FILE IN THE TOWN CLERK'S OFFICE AND ARE NOT PUBLISHED ONLINE, so applicability cannot be settled from the code text — the Planning Board determines it during subdivision review. Schedule I additionally makes one- and two-family dwellings and mobile homes SPECIAL PERMIT uses within the overlay rather than permitted uses, and marks multi-family dwellings and most commercial and industrial uses as prohibited outright. | — | — | — | Special permit |
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Size limits on record in Franklin
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 Franklin:
- Rural-I District — THE STATE AND COUNTY HIGHWAY CORRIDOR, defined geographically rather than by map colour: § 404A includes all lands within 500 FEET OF THE CENTER LINE of a State or County highway with DIRECT FRONTAGE on the right-of-way, where the highway is one maintained by the County or State as of the ordinance's effective date and shown on the Zoning Map. Its purpose is to allow a variety of mixed uses appropriate to a high-volume, good-access road. Minimum lot size 1 acre; minimum frontage 250 ft; maximum height 35 ft; side and rear setbacks 20 ft each; maximum lot coverage 25%; maximum lot depth-to-width ratio 4:1, AND FOR EACH INCREMENT IN THAT RATIO THE REQUIRED FRONTAGE EXTENDS BY 50 FT — a shape rule that quietly penalises deep narrow lots twice over. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. THIS DISTRICT IS THE ONE WHERE THAT ASSUMPTION IS LEAST SAFE, because it fronts State and County highways whose rights-of-way are routinely WIDER than 50 ft: on a 66 ft right-of-way the same rule gives about 67 ft from the lot line, and on an 80 ft right-of-way about 60 ft. The recorded 75 is therefore the conservative end. Check the actual right-of-way width before siting. Permitted uses are one one- or two-family dwelling per lot, one mobile home per lot, agricultural practices, forestry management and wildlife management; everything else in Schedule I is a special permit use or prohibited. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
- Rural-III District — THE TOWN ROAD CORRIDOR: § 405A includes all lands within 500 FEET OF THE CENTER LINE of a town road with direct frontage on the right-of-way, counting roads maintained by the Town as of the ordinance's effective date BUT EXPRESSLY EXCLUDING SEASONAL USE ROADS — a parcel fronting a seasonal road falls to Rural V and its 5-acre minimum instead, which is a 2-acre difference decided entirely by the road's maintenance status. Purpose: lower-density residential, agriculture and limited commercial. Minimum lot area 3 acres; minimum frontage 300 ft; maximum height 35 ft; side and rear setbacks 25 ft each; maximum lot coverage 20%; maximum lot depth-to-width ratio 4:1. Front setback 75 ft from the road centre line, recorded as 50 ft, being the lot-line equivalent on a 50 ft right-of-way; on a narrower right-of-way the rule binds harder (a 33 ft right-of-way gives about 58.5 ft). READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. Permitted uses and accessory uses are the same list as Rural I. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
- Rural-V District — THE BACKLAND DISTRICT AND THE DEFAULT FOR REMOTE PARCELS: § 406A includes all lands NOT within 500 ft of an existing Town, County or State right-of-way, plus all lands fronting on Town "Seasonal Use Only" roads as designated on the Zoning Map. Purpose: only low-density residential development with limited commercial uses. Minimum lot area 5 acres; minimum frontage 350 ft, the largest in the town; maximum height 35 ft; side and rear setbacks 30 ft each; maximum lot depth-to-width ratio 4:1. Front setback 75 ft from the road centre line, recorded as 50 ft on the 50 ft right-of-way basis. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. § 406F(6) reads "Maximum lot coverage: Fifteen per cent (25%)" — the words say fifteen and the numeral in brackets says twenty-five, and they cannot both be right. 15 is recorded on two grounds. First, where words and figures conflict the words conventionally govern. Second, and more persuasively, the town's coverage figures form a clean descending series as the districts get more rural — Hamlet 25%, Rural I 25%, Rural III 20%, Public Water Supply 10% — and 15% is exactly the missing step, while 25% would make the most rural district identical to the least. THE SCHEDULE THAT WOULD SETTLE IT DOES NOT EXIST: the table of contents lists "SCHEDULE II — TABLE OF DIMENSIONAL REGULATIONS" at page 73, but the document ends at page 73 with Schedule I and contains no Schedule II at all. Raise this with the Code Enforcement Officer before relying on either figure; the difference is 10% of a 5-acre lot. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
- Hamlet District — THE HAMLET OF TREADWELL specifically, as denoted on the Zoning Map; this is a single named crossroads community rather than a general category, and Franklin's other settlement, the VILLAGE of Franklin, is a separate jurisdiction entirely and not governed by this ordinance. Purpose: to recognise a crossroads community where residential and commercial business uses exist in harmony, providing basic services for the surrounding community and homes for the people who provide them. Minimum lot area ONE-HALF ACRE, the smallest in the town; minimum frontage 100 ft; maximum height 35 ft; side and rear setbacks 20 ft each; maximum lot coverage 25%; maximum depth-to-width ratio 3:1, tighter than the 4:1 used everywhere else. Front setback 55 ft from the road centre line, which on a 50 ft right-of-way resolves to 30 ft from the front lot line — recorded as 30. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise. Permitted uses and accessory uses are the same lists as Rural I, so the district's mixed character comes from Schedule I's special permit column rather than from its by-right uses. ADU: there is no accessory apartment in this code, but the accessory-use list includes a FARM LABOR DWELLING, NO MORE THAN TWO — a genuine second (and third) dwelling unit permitted as an accessory use, with an occupancy condition limiting it to farm labour. That is why aduPermitted is special-provisions here rather than not-permitted. The general route to a second unit is different and easier: a TWO-FAMILY DWELLING is a permitted use in this district.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
- Public Water Supply District — THE MOST RESTRICTIVE DISTRICT IN THE TOWN, AND THE ONE MOST LIKELY TO BE MISSED because it is defined by a radius rather than by a mapped block: § 408A includes all lands WITHIN A 500-FOOT RADIUS OF THE PUBLIC WATER SUPPLY WELLS AND SPRINGS for the Village of Franklin and the hamlet of Treadwell. The stated rationale is the wellhead cone of depression — contamination entering groundwater within it is certain to reach the pumping well — so the restrictions are about water, not density. Everything, including a single-family dwelling, is a SPECIAL PERMIT use — one one- or two-family dwelling per lot, one mobile home per lot, agricultural practices, forest management, wildlife management practices, public utilities and facilities, public parks and recreation facilities, and the accessory uses listed for the Rural I district, all only by special permit from the Planning Board. Minimum lot size 10 ACRES, twice Rural V's; minimum frontage 300 ft; maximum height 35 ft; side and rear setbacks 30 ft; maximum lot coverage 10%, the tightest in the town; maximum lot depth-to-width ratio 4:1. NOTE THE FRONT SETBACK IS THE ONE DISTRICT MEASURED FROM THE RIGHT-OF-WAY RATHER THAN THE CENTRE LINE: § 408F(4) states 200 FEET FROM RIGHT-OF-WAY, so 200 is recorded directly with no conversion, and it is by far the deepest front setback in the town. READ THE COVERAGE BASIS: § 202 defines LOT COVERAGE as the proportion of lot area covered by IMPERVIOUS SURFACE INCLUDING BUILDINGS AND OFF-STREET PARKING AREAS, so this percentage is an impervious cap and not a building-footprint cap. On a rural lot the driveway and parking consume a real share of it. Franklin is the third Delaware town found with this definition, after Delhi and Sidney — in this county, assume impervious unless the code says otherwise.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
- Development Limitations Overlay District — AN OVERLAY, NOT A STANDALONE DISTRICT: § 409D makes minimum lot size, minimum frontage, maximum height, front setback, side and rear setbacks, maximum lot coverage and the depth-to-width ratio ALL "same as the underlying district", which is why every dimensional field here is null. Exactly one thing changes, and it changes yield rather than dimensions. § 409D(1) applies only WHERE THE ORIGINAL PARCEL BEING SUBDIVIDED HAS MORE THAN FIFTY PERCENT of its land area in one or more Development Limitations. Above that threshold the maximum number of lots allowed per acre of the ORIGINAL parcel is 0.44 in Rural I, 0.15 in Rural III and 0.09 in Rural V. Read those as acres per lot and the effect is stark: 2.27 acres per lot in Rural I against a 1-acre minimum, 6.67 acres in Rural III against 3, and 11.1 ACRES PER LOT IN RURAL V AGAINST A 5-ACRE MINIMUM — the overlay more than doubles the land needed per lot in every district. The 50% threshold is what makes Franklin's version less pervasive than Middletown's, whose overlay fires when any two of five limitations exist "to any degree", but it is also all-or-nothing: a parcel at 51% encumbrance takes the full density cap. TRIGGERS: flood hazard areas including those on Flood Hazard Boundary Map No. H 01-10 dated 1988-01-18; freshwater wetlands as defined and protected by the NYS Freshwater Wetlands Act; steep slopes of 15% OR MORE; and high elevation areas of 2,000 FEET OR GREATER — the same 2,000 ft trigger as the Town of Delhi and 500 ft lower than Middletown's. PROCESS: the Code Enforcement Officer screens every zoning permit application for construction in the Flood Hazard Area or within 100 ft of a NYS regulated wetland; no zoning permit issues for construction in the Flood Hazard Area until the Planning Board grants a Special Permit, and none within 100 ft of a regulated wetland until the applicant has NYSDEC approval. Plans must comply with the NYS Wetlands Act and with Local Law No. 1 of 1987, Flood Damage Prevention. THE OVERLAY MAPS ARE ON FILE IN THE TOWN CLERK'S OFFICE AND ARE NOT PUBLISHED ONLINE, so applicability cannot be settled from the code text — the Planning Board determines it during subdivision review. Schedule I additionally makes one- and two-family dwellings and mobile homes SPECIAL PERMIT uses within the overlay rather than permitted uses, and marks multi-family dwellings and most commercial and industrial uses as prohibited outright.§ 512 requires a habitable floor area of at least 800 sq ft for one- and two-family dwellings
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 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 under a full permit regime — Local Law No. 3 of 2024, the "Transient and Short-Term Residential Rentals Local Law", which is a standalone instrument and NOT part of the zoning ordinance. It defines a short-term residential rental as a property used as a short-term transient rental UNDER 30 DAYS, whether unoccupied by the owner or occupied by both owner and a transient guest, so hosted stays are caught as well as whole-house rentals. THE PERMIT IS ANNUAL AND INSPECTION-GATED: the owner requests an inspection from the Office of Code Enforcement, and on passing it and paying the annual fee the Code Enforcement Officer issues the permit. The rental registry year runs 1 January to 31 December and the permit expires each 31 December. A SEPARATE APPLICATION, FEE AND PERMIT IS REQUIRED FOR EACH DWELLING UNIT. THE COUNTY TAX HOOK IS THE PART MOST LIKELY TO CATCH AN OUT-OF-AREA BUYER: no permit issues without proof of registration with DELAWARE COUNTY for collecting the occupancy tax, or proof on county letterhead that the property is exempt — and no RENEWAL issues without proof that all occupancy taxes owed to the county have been paid. OCCUPANCY IS CAPPED AT TWO PERSONS OVER THE AGE OF TWO PER BEDROOM for the entire premises, and the Code Enforcement Office may cut that further based on the number, size, configuration and furnishings of the sleeping rooms. THE 30-MILE RULE SHAPES REMOTE OWNERSHIP: a LOCAL MANAGER responsible for day-to-day operation must be contactable day or night and MUST RESIDE WITHIN 30 MILES of the unit; an owner whose primary residence is further than 30 miles away is a "non-resident owner" and must designate one. A local agent must be able to ARRIVE IN PERSON WITHIN 60 MINUTES of being notified of an emergency. For a non-resident owner the designation also confers criminal jurisdiction: service of an appearance ticket on the local manager as agent is good service on the owner as if served personally within Delaware County. OTHER OPERATING TERMS: on-site parking is mandatory and street parking is prohibited, with spaces at least 10 by 20 ft and no RV or camping-unit parking during the permit period; a 911 location sign must be posted clearly at the end of the driveway; proof of liability insurance and a bed tax identification number are required; house rules must be submitted and must carry emergency-service and local-manager contacts; the permit must be displayed inside the unit and an emergency contact card posted on the inside of the front or main door; records of rental dates and guest numbers must be kept and produced to the Code Enforcement Officer on request; property boundaries must be clearly delineated; and the permit may not be assigned, sold or transferred without prior written notice to the Code Enforcement Officer. Renewal requires either an affidavit that nothing about the unit has changed or an amendment setting out what did. A gap year resets you to initial-applicant status. THE FEE IS NOT IN THE LAW — it is set by Town Board resolution and changes from time to time, so ask the Town Clerk for the current figure before underwriting. 2 of 2024 "Vacation Campground", which is a separate instrument and likely governs a different transient-lodging form on the same land. Separate question from whether you can build the unit.
Sizing up a specific parcel in Franklin?
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 Franklin runs $191–250/sq ft, about $345k–450k at 1,800 sq ft , plus roughly $38,940 for a conforming lot. See what it costs to build a house in Franklin.
ADU cost in nearby towns
Andes
800 sq ft ≈ $185k–245k
Delhi
800 sq ft ≈ $185k–245k
Middletown
800 sq ft ≈ $185k–245k
Sidney
800 sq ft ≈ $185k–245k
Walton
800 sq ft ≈ $185k–245k
Delhi (Village)
800 sq ft ≈ $185k–245k
All Delaware County towns: Andes · Delhi · Middletown · Sidney · Walton · Delhi (Village) · Hancock (Village) · Sidney (Village) · Walton (Village)
More on Franklin: Can you build an ADU here? · Zoning for new construction · Delaware County build cost
ADU cost in Franklin: common questions
How much does it cost to build an ADU in Franklin, NY?
An 800 sq ft accessory dwelling unit in Town of Franklin runs roughly $185k–245k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $125k–160k. 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 Franklin?
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 $233–305/sq ft against $191–250/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Franklin?
Town of Franklin has 6 districts. 4 districts allow ADUs with occupancy restrictions, 2 require a special-use permit. Check the specific address with the free ADU checker or confirm with the building department before you spend money on design.
Can I rent an ADU in Franklin short term?
Short-term rentals allowed with local rules for Town of Franklin. 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 Delaware 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 Franklin vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-24; verify with the municipality before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).