Beacon · ADU cost
What it costs to build an ADU in Beacon, NY
An 800 sq ft accessory dwelling unit in Beacon runs roughly $210k–275k, or about $263–345/sq ft, and that per-square-foot figure sits deliberately above the $215–282/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 city 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 City of Beacon maps 23 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
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ADU cost by size in Beacon
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Dutchess County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $349–$457 | $140k–185k |
| 600 sq ft | One bedroom | $292–$382 | $175k–230k |
| 800 sq ft | One bedroom, larger | $263–$345 | $210k–275k |
| 1,000 sq ft | Two bedroom | $246–$322 | $245k–320k |
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 | $8–$12 | $8 | — |
| Foundation | $17–$24 | $17 | — |
| Framing | $27–$34 | $27 | — |
| Envelope - roof, siding, windows | $34–$43 | $34 | — |
| Plumbing | $29–$36 | $17 | 55% |
| Electrical | $19–$25 | $13 | 35% |
| HVAC | $24–$30 | $15 | 45% |
| Insulation | $8–$10 | $8 | — |
| Interior finishes | $34–$46 | $29 | 15% |
| Millwork & cabinetry | $19–$29 | $12 | 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 Beacon 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 Residence 120,000 Square Feet | 2.75 ac | 70 / 50 / 75 ft | 35 ft | Occupancy restricted |
| One-Family Residence 80,000 Square Feet | 1.84 ac | 45 / 30 / 50 ft | 35 ft | Occupancy restricted |
| One-Family Residence 40,000 Square Feet | 0.92 ac | 35 / 25 / 50 ft | 35 ft | Occupancy restricted |
| One-Family Residence 20,000 Square Feet | 0.46 ac | 25 / 20 / 40 ft | 35 ft | Occupancy restricted |
| One-Family Residence 10,000 Square Feet | 0.23 ac | 20 / 15 / 35 ft | 35 ft | Occupancy restricted |
| One-Family Residence 7,500 Square Feet | 0.17 ac | 15 / 10 / 25 ft | 35 ft | Occupancy restricted |
| One-Family Residence 5,000 Square Feet | 0.11 ac | 10 / 10 / 20 ft | 35 ft | Occupancy restricted |
| Residence District 7,500 Square Feet per Unit | 2 ac | 20 / 25 / 50 ft | 35 ft | Occupancy restricted |
| Residence District 6,000 Square Feet per Unit | 2 ac | 50 / 25 / 50 ft | 35 ft | Occupancy restricted |
| Residence District 5,000 Square Feet per Unit | 0.11 ac | 30 / 10 / 25 ft | 35 ft | Occupancy restricted |
| Residence District 4,000 Square Feet per Unit | 0.11 ac | 40 / 20 / 40 ft | 35 ft | Occupancy restricted |
| Residence District 3,000 Square Feet per Unit | 0.11 ac | 30 / 20 / 25 ft | 45 ft | Occupancy restricted |
| Residence District 1,800 Square Feet per Unit | 0.11 ac | 30 / 20 / 25 ft | 100 ft | Occupancy restricted |
| Residence District 1,700 Square Feet per Unit | 0.11 ac | 30 / 20 / 25 ft | 55 ft | Occupancy restricted |
| Transitional | 0.11 ac | 10 / 10 / 20 ft | 35 ft | Occupancy restricted |
| General Business | — | 15 / 20 / 25 ft | 35 ft | Occupancy restricted |
| Corridor Mixed-Use Service | — | 0 / 0 / 20 ft | 38 ft | Occupancy restricted |
| Linkage | — | 0 / 0 / 25 ft | 48 ft | Occupancy restricted |
| Fishkill Creek Development | 2 ac | — | 40 ft | Occupancy restricted |
| Waterfront Park | 1 ac | 10 / - / - ft | 35 ft | Occupancy restricted |
| Transit Station | 3 ac | — | — | Occupancy restricted |
| Light Industrial | — | 20 / 20 / 25 ft | 35 ft | Occupancy restricted |
| Heavy Industrial | — | 30 / 20 / 25 ft | 40 ft | Occupancy restricted |
One-Family Residence 120,000 Square Feet, One-Family Residence 80,000 Square Feet, One-Family Residence 40,000 Square Feet, One-Family Residence 20,000 Square Feet, One-Family Residence 10,000 Square Feet, One-Family Residence 7,500 Square Feet - No building may contain more than 1 dwelling unit. On a development proposal covering more than three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
- The overall lot minimum and the land per dwelling unit both bind.
- Height is also capped at 2 1/2 stories.
One-Family Residence 5,000 Square Feet - The minimum lot is 5,000 sq ft but the area per unit is 2,500 sq ft, so two dwelling units are allowed on it, and no building may contain more than 2 dwelling units.
- On a development proposal covering more than three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
- Height is also capped at 2 1/2 stories.
Residence District 7,500 Square Feet per Unit - A multifamily building may cover only 15% of the lot, and no building may contain more than 12 dwelling units. The front yard is a range of 20 to 35 ft rather than a plain minimum.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart, and height is also capped at 3 stories.
- On proposals over three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
Residence District 6,000 Square Feet per Unit - A multifamily building may cover only 15% of the lot, and no building may contain more than 16 dwelling units.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart, and height is also capped at 2 1/2 stories.
- On proposals over three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
Residence District 5,000 Square Feet per Unit - A multifamily building may cover only 20% of the lot, and no building may contain more than 16 dwelling units.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart, and height is also capped at 3 stories.
- On proposals over three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
Residence District 4,000 Square Feet per Unit - A multifamily building may cover only 20% of the lot, and no building may contain more than 20 dwelling units.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart, and height is also capped at 2 1/2 stories.
- On proposals over three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
Residence District 3,000 Square Feet per Unit - A multifamily building may cover only 20% of the lot, and no building may contain more than 24 dwelling units.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart, and height is also capped at 3 1/2 stories.
- On proposals over three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
Residence District 1,800 Square Feet per Unit - No more than 65% of the dwelling units in a development may be in buildings over 3 1/2 stories, and no building of 3 1/2 stories or less may hold more than 24 units. A multifamily building may cover only 25% of the lot.
- Height is also capped at 10 stories.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart.
- On proposals over three acres, lot area per unit is net of surface water, federal regulatory floodway, state or federally regulated wetland and predevelopment slopes of 25% or steeper (§ 223-63).
Residence District 1,700 Square Feet per Unit - One story of parking underneath a building does not count toward the story or height limit, and no building may exceed 150 ft in length. A multifamily building may cover only 25% of the lot, and no building may contain more than 36 dwelling units.
- Height is also capped at 4 1/2 stories.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Buildings on the same lot must stand at least 30 ft apart.
- On proposals over three acres, lot area per unit is net of surface water, federal regulatory floodway, state or federally regulated wetland and predevelopment slopes of 25% or steeper (§ 223-63).
Transitional - Lot area per dwelling unit is half the minimum lot size per dwelling unit of the least restrictive adjoining residential district, so it depends on what the parcel adjoins.
- The Planning Board may allow lots as small as 1,800 sq ft for attached or semi-attached single-family homes if gross tract density stays within what the district allows for multiple dwellings.
- For such a subdivision side yards may be cut to zero, but an end unit keeps at least half the side yard of the least restrictive adjoining residential district.
- A multifamily development needs 2,000 sq ft of landscaped recreation or usable open space for the first 20 dwelling units and 100 sq ft for each unit beyond that.
- Height is also capped at 2 1/2 stories.
General Business - General Business sets no overall minimum lot area, no lot width and no coverage limit. Where dwellings are built it takes 1,500 sq ft of lot area per dwelling unit, and lot depth must be at least 100 ft.
Corridor Mixed-Use Service - The front yard is a range of 0 to 10 ft rather than a plain minimum, and at least 10% of the lot must be open space.
- Height is also capped at 3 stories.
Linkage - The front yard is a range of 0 to 20 ft and the side yard a range of 0 to 30 ft, rather than plain minimums. At least 15% of the lot must be open space.
- Height is also capped at 4 stories.
Fishkill Creek Development - At least 30% of the lot must be open space, and the overall lot minimum and 3,960 sq ft per dwelling unit both bind. On a development proposal covering more than three acres, lot area per dwelling unit is calculated on net acreage (§ 223-63).
- Surface water, federal regulatory floodway, state or federally regulated wetland, and predevelopment slopes of 25% or steeper come off the lot area first.
- Height is also capped at 3 stories.
Waterfront Park - Height is capped at 2 1/2 stories as well as 35 ft.
Transit Station - Height by location: north of West Main Street an average of four stories over parking and no more than an average of 75 ft above the existing Metro-North parking grade; south of the LI district an average of three stories, 32 ft at Beekman Street and 70 ft above that grade.
- At least 15% of the site must be open space, of which 10% must be publicly accessible.
- Yards and the rest of the dimensional rules come from Article IVA.
Light Industrial - At least 20% of the lot must be open space.
- The overall lot minimum and 1,500 sq ft of lot area per dwelling unit both bind.
Heavy Industrial - At least 20% of the lot must be open space.
Size limits on record in Beacon
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 Beacon:
- One-Family Residence 120,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 80,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 40,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 20,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 10,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 7,500 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- One-Family Residence 5,000 Square FeetThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 7,500 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 6,000 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 5,000 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 4,000 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 3,000 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 1,800 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Residence District 1,700 Square Feet per UnitThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- TransitionalThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- General BusinessThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Corridor Mixed-Use ServiceThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- LinkageThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Fishkill Creek DevelopmentThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Waterfront ParkThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Transit StationThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Light IndustrialThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
- Heavy IndustrialThe Building Inspector approves it where setbacks are met; otherwise, or where it exceeds both 1,000 sq ft and 50% of the house's floor area, site plan approval is needed.
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 Central Hudson 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. A short-term rental permit is required for every rental under 30 days, and only a primary residence qualifies. Rentals are capped at 100 days a year, with no booking longer than 30 consecutive days. Separate question from whether you can build the unit.
- Zoning codeecode360.com/7066171
- Building dept(845) 838-5011
Sizing up a specific parcel in Beacon?
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Building a full house instead?
A standard-finish house in Beacon runs $215–282/sq ft, about $390k–510k at 1,800 sq ft , plus roughly $26,630 for a conforming lot. See what it costs to build a house in Beacon.
ADU cost in nearby towns
All Dutchess County towns: Poughkeepsie (City) · Amenia · Beekman · Clinton · Dover · East Fishkill · Fishkill · Hyde Park · La Grange · Milan · North East · Pawling · Pine Plains · Pleasant Valley · Poughkeepsie · Red Hook · Rhinebeck · Stanford · Union Vale · Wappinger · Washington · Fishkill (Village) · Millbrook (Village) · Millerton (Village) · Pawling (Village) · Red Hook (Village) · Rhinebeck (Village) · Tivoli (Village) · Wappingers Falls (Village)
More on Beacon: Can you build an ADU here? · Zoning for new construction · Dutchess County build cost
ADU cost in Beacon: common questions
How much does it cost to build an ADU in Beacon, NY?
An 800 sq ft accessory dwelling unit in City of Beacon runs roughly $210k–275k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $140k–185k. 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 Beacon?
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 $263–345/sq ft against $215–282/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in Beacon?
City of Beacon has 23 districts. All districts allow ADUs with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (845) 838-5011 before you spend money on design.
Can I rent an ADU in Beacon short term?
Short-term rentals allowed with local rules for City of Beacon. 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 Dutchess 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 City of Beacon vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-16; verify with the building department at (845) 838-5011 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.