Beekman · ADU cost
What it costs to build an ADU in Beekman, NY
An 800 sq ft accessory dwelling unit in Beekman 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 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 Beekman maps 13 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 Beekman
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 Beekman 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 |
|---|---|---|---|---|
| Residential 135,000 Square Feet District | 3.1 ac | 100 / 40 / 60 ft | 35 ft | Special permit |
| Residential 90,000 Square Feet District | 2.07 ac | 75 / 30 / 40 ft | 35 ft | Special permit |
| Residential 45,000 Square Feet District | 1.03 ac | 50 / 20 / 35 ft | 35 ft | Special permit |
| Residential-Mobile Home District | — | 35 / 20 / 20 ft | 35 ft | No |
| Poughquag Hamlet District | 1.03 ac | 50 / 20 / 35 ft | 35 ft | Special permit |
| Beekmanville Hamlet District | 1.03 ac | 50 / 20 / 35 ft | 35 ft | Special permit |
| Residential District Condominium Units District | — | 35 / 20 / 35 ft | 35 ft | No |
| Sylvan Cottage District | 0.11 ac | 10 / 10 / 10 ft | 35 ft | No |
| Town Center District | 1 ac | 0 / 10 / 35 ft | 35 ft | No |
| Neighborhood Shopping District | 0.34 ac | 60 / 40 / 40 ft | 35 ft | No |
| Highway Commercial District | 0.46 ac | 60 / 40 / 40 ft | 35 ft | No |
| Mixed Commercial - Light Industrial District | 2.5 ac | 150 / 80 / 80 ft | 45 ft | No |
| Land Conservation District | — | — | — | No |
Residential 135,000 Square Feet District - Besides the 6% building coverage, impervious surfaces including the building are capped at 10% of the lot, and driveways and parking count against that cap. The lot also needs at least 100 ft of road frontage, separate from the lot width.
Residential 90,000 Square Feet District - Besides the 8% building coverage, impervious surfaces including the building are capped at 12% of the lot, and driveways and parking count against that cap. The lot also needs at least 100 ft of road frontage, separate from the lot width.
Residential 45,000 Square Feet District - Besides the 10% building coverage, impervious surfaces including the building are capped at 15% of the lot, and driveways and parking count against that cap. The lot also needs at least 100 ft of road frontage, separate from the lot width.
Residential-Mobile Home District - Lot area, lot width and road frontage are marked not applicable, as the district is regulated as a mobile home development rather than lot by lot.
- A parking lot must be at least 150 ft from a residential district.
Poughquag Hamlet District, Beekmanville Hamlet District - The figures shown are for a lot without public water and sewer. With public water and sewer the minimum lot drops from 45,000 sq ft to 11,250 sq ft and building coverage rises from 10% to 50%.
- With public water and sewer the yards become 15 ft front, 10 ft side and 30 ft rear, and lot width and road frontage drop to 50 ft each.
- With public water and sewer the minimum interior living space drops from 1,000 sq ft to 500 sq ft.
- Impervious surfaces, including the building, are capped at 15%, or 80% with public water and sewer; driveways and parking count against this cap.
- Without public water and sewer the lot needs at least 100 ft of road frontage, separate from the lot width.
Residential District Condominium Units District - There is no lot-area minimum; density is capped at 8 dwelling units per acre instead. Impervious surfaces, including the building, are capped at 50%, and driveways and parking count against that cap.
- Minimum road frontage is 50 ft, separate from the lot width.
Sylvan Cottage District - Minimum lot area depends on bedrooms (§ 155-8H): at least 5,000 sq ft for a one- or two-bedroom unit, at least 10,000 sq ft for three and at least 20,000 sq ft for four. Yards are 10 ft per story, so a two-story building needs 20 ft on every side.
- Floor area per unit is capped at 1,000 sq ft for one or two bedrooms, 1,250 sq ft for three and 1,500 sq ft for four.
- No building may stand closer than 15 ft to another building in SC or in an adjoining residential district.
- Impervious surfaces are capped at 75% of the lot.
Town Center District - The front yard is a range of 0 to 15 ft, so a building may not sit further back than 15 ft. Every parcel must grant the Town a 35 ft utility easement, located as the Planning Board directs.
- Density is capped at 12 residential units per acre, separate from the lot minimum.
- Commercial on the lower level with residential above is as of right; residential on both levels needs a special use permit.
- A residential lot may be 6,000 to 10,000 sq ft where it is used for an attached house or a condominium.
- Impervious surfaces, including the building, are capped at 50%, and driveways and parking count against that cap.
- Minimum road frontage is 100 ft, separate from the lot width.
Neighborhood Shopping District, Highway Commercial District - Side and rear yards rise from 40 ft to 60 ft where the lot abuts a residential district. Besides the 25% building coverage, impervious surfaces including the building are capped at 50%, and driveways and parking count against that cap.
- A parking lot must be at least 60 ft from a residential district.
- Minimum road frontage is 125 ft.
Mixed Commercial - Light Industrial District - Side and rear yards rise from 80 ft to 150 ft where the lot abuts a residential district. Besides the 30% building coverage, impervious surfaces including the building are capped at 50%, and driveways and parking count against that cap.
- A parking lot must be at least 60 ft from a residential district.
- Minimum road frontage is 125 ft.
Land Conservation District - Confirm the dimensional standards that apply in LC with the Town before relying on this district.
- The district's purpose is to protect sensitive resource areas, including former public land conveyed into private hands.
Size limits on record in Beekman
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 Beekman:
- Residential 135,000 Square Feet DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Residential 90,000 Square Feet DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Residential 45,000 Square Feet DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Residential-Mobile Home DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Poughquag Hamlet DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Beekmanville Hamlet DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Residential District Condominium Units DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Sylvan Cottage DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Town Center DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Neighborhood Shopping DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Highway Commercial DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Mixed Commercial - Light Industrial DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
- Land Conservation DistrictFloor area must be over 400 sq ft and under 800 sq ft, and not more than 35% of the house, with no more than one bedroom.
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. Short-term rentals need a Town permit under Local Law No. 2 of 2022 (Chapter 126.1), and an owner may operate only one short-term rental property. Separate question from whether you can build the unit.
- Zoning codeecode360.com/6239722
- Building dept(845) 724-5300
Sizing up a specific parcel in Beekman?
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Building a full house instead?
A standard-finish house in Beekman runs $215–282/sq ft, about $390k–510k at 1,800 sq ft , plus roughly $92,203 for a conforming lot. See what it costs to build a house in Beekman.
ADU cost in nearby towns
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More on Beekman: Can you build an ADU here? · Zoning for new construction · Dutchess County build cost
ADU cost in Beekman: common questions
How much does it cost to build an ADU in Beekman, NY?
An 800 sq ft accessory dwelling unit in Town of Beekman 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 Beekman?
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 Beekman?
Town of Beekman has 13 districts. 8 districts prohibit ADUs, 5 require a special-use permit. Check the specific address with the free ADU checker or confirm with the building department at (845) 724-5300 before you spend money on design.
Can I rent an ADU in Beekman short term?
Short-term rentals allowed with local rules for Town of Beekman. 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 Town of Beekman 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) 724-5300 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.