La Grange · ADU cost
What it costs to build an ADU in La Grange, NY
An 800 sq ft accessory dwelling unit in La Grange 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 La Grange maps 14 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 La Grange
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 La Grange 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 Flexible-Density | 1.8365 ac | 55 / 20 / 20 ft | 35 ft | Occupancy restricted |
| Residential Low-Density | 2.7548 ac | 55 / 40 / 40 ft | 35 ft | Occupancy restricted |
| Residential Moderate-Density | 1.8365 ac | 55 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Residential Frank & Sleight | — | 35 / 10 / 20 ft | 35 ft | — |
| Town Center Residential | 0.1377 ac | — | 35 ft | Occupancy restricted |
| Town Park | — | 35 / 100 / 100 ft | 35 ft | — |
| Overlook Planned Development | — | 25 / 100 / 75 ft | 35 ft | — |
| Town Center Business | 0.1377 ac | - / 0 / 6 ft | 50 ft | Occupancy restricted |
| Hamlet | 0.6887 ac | 10 / 5 / 10 ft | 35 ft | Occupancy restricted |
| Manchester Gateway Hamlet | — | 10 / 5 / 6 ft | 50 ft | — |
| Gateway Hamlet | — | 15 / 5 / 10 ft | 35 ft | Occupancy restricted |
| General Business | 0.9183 ac | 40 / 20 / 20 ft | 35 ft | No |
| Commercial | 0.6887 ac | 40 / 20 / 20 ft | 35 ft | No |
| Industrial | 1.8365 ac | 75 / 20 / 20 ft | 35 ft | No |
Residential Flexible-Density — RFD sets its lot area by utilities and the base row is the unserviced case: 80,000 sq ft on a private well and septic system, 60,000 with either public water or public sewer, and 40,000 with both. The rest of the schedule moves with it — at 40,000 sq ft the lot need only be 50 ft wide at any point with 50 ft of Town frontage and 125 ft on a county or state highway, at 60,000 it is 75 ft wide, and at 80,000 it is 100 ft wide with 75 ft and 200 ft of frontage. Building coverage is 15% at the two smaller sizes and 10% at 80,000, and floor area 30%, 25% and 20% respectively. On a Town road the front yard is TWO measurements and both must be satisfied: 55 ft from the front lot line, which is the figure recorded, and 80 ft from the CENTRE LINE of the road. On a state or county road the front yard is 90 ft. Lot width is tested twice: 150 ft along the building line, which is the figure recorded, and 100 ft at ANY point. Minimum lot frontage is 75 ft on a Town right-of-way and 200 ft on a county or state highway. A square of at least 150 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 10% of the lot, building FLOOR area may reach 20% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 20%. A dwelling unit needs at least 1000 sq ft of floor area. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Residential Low-Density — Minimum Town-road frontage may be reduced to 50 ft on the circular end of a cul-de-sac. On a Town road the front yard is TWO measurements and both must be satisfied: 55 ft from the front lot line, which is the figure recorded, and 80 ft from the CENTRE LINE of the road. On a state or county road the front yard is 90 ft. Lot width is tested twice: 200 ft along the building line, which is the figure recorded, and 150 ft at ANY point. Minimum lot frontage is 100 ft on a Town right-of-way and 225 ft on a county or state highway. A square of at least 200 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 10% of the lot, building FLOOR area may reach 20% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 15%. A dwelling unit needs at least 1200 sq ft of floor area. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Residential Moderate-Density — Minimum Town-road frontage may be reduced to 50 ft on the circular end of a cul-de-sac. On a Town road the front yard is TWO measurements and both must be satisfied: 55 ft from the front lot line, which is the figure recorded, and 80 ft from the CENTRE LINE of the road. On a state or county road the front yard is 90 ft. Lot width is tested twice: 200 ft along the building line, which is the figure recorded, and 100 ft at ANY point. Minimum lot frontage is 75 ft on a Town right-of-way and 200 ft on a county or state highway. A square of at least 200 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 10% of the lot, building FLOOR area may reach 20% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 20%. A dwelling unit needs at least 1000 sq ft of floor area. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Residential Frank & Sleight — RFS publishes no lot area, no frontage on a county or state highway and no coverage limits, because development here is part of an open space subdivision under § 240-32 and no further subdivision is permitted. The side yard is 10 ft on one side and 15 ft on the other with a combined minimum of 25 ft, and principal structures must in all cases stand at least 25 ft apart. On a Town road the front yard is TWO measurements and both must be satisfied: 35 ft from the front lot line, which is the figure recorded, and 60 ft from the CENTRE LINE of the road. Lot width is tested twice: 100 ft along the building line, which is the figure recorded, and 60 ft at ANY point. Minimum lot frontage is 60 ft on a Town right-of-way and not set on a county or state highway. A square of at least 75 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover an unstated share of the lot, building FLOOR area may reach an unstated share of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed an unstated share. A dwelling unit needs at least 1000 sq ft of floor area. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Town Center Residential — The schedule sets NO single-family lot area for TCR without public sewers; the 6,000 sq ft recorded is the figure WITH public sewers, and a townhouse on public sewers needs 2,500 sq ft. The Planning Board may approve a density of six to twelve dwelling units per acre, and at its discretion a 4,000 sq ft single-family lot or a 1,650 sq ft townhouse lot, but never above twelve units per acre overall, and never more than five single-family units on lots under 6,000 sq ft in a row without a break. Yards are not on this schedule at all — they are in Schedule B4. Townhouses and apartments are excluded from the 70% building floor area limit. Minimum lot frontage is 25 ft on a Town right-of-way and 25 ft on a county or state highway. The schedule sets THREE area limits: buildings may cover 40% of the lot, building FLOOR area may reach 70% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 60%. A dwelling unit needs at least 500 sq ft of floor area, and an apartment 400 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Town Park — Town Park publishes no lot area, no lot width and no coverage limits. On a state or county road the front yard is 100 ft. A square of at least 150 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover an unstated share of the lot, building FLOOR area may reach an unstated share of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed an unstated share. A dwelling unit needs at least 600 sq ft of floor area, and an apartment 400 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Overlook Planned Development — OPD publishes no lot area and no Town-road frontage; its frontage requirement is 500 ft on a county or state highway. On a state or county road the front yard is 25 ft. Minimum lot frontage is not set on a Town right-of-way and 500 ft on a county or state highway. A square of at least 200 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 15% of the lot, building FLOOR area may reach 25% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 70%. A dwelling unit needs at least 1000 sq ft of floor area, and an apartment 400 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Town Center Business — The 6,000 sq ft recorded is the single-family figure WITH public sewers; the schedule sets none without them, and a townhouse on public sewers needs 2,500 sq ft. The Planning Board may approve six to twelve dwelling units per acre, and at its discretion a 4,000 sq ft single-family lot or a 1,650 sq ft townhouse lot. Front yards are in Schedule B3, not here. The Planning Board may approve a ZERO-foot rear yard. Minimum lot frontage is 25 ft on a Town right-of-way and 25 ft on a county or state highway. The schedule sets THREE area limits: buildings may cover 85% of the lot, building FLOOR area may reach an unstated share of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 90%. A building must stand 25 ft back from a residential district boundary line. A dwelling unit needs at least 500 sq ft of floor area, and an apartment 500 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 50 ft.
Hamlet — A single-family lot served by public sewers needs 8,000 sq ft rather than 30,000, and a townhouse on public sewers 6,250. On a state or county road the front yard is 10 ft. Lot width is tested twice: 50 ft along the building line, which is the figure recorded, and 30 ft at ANY point. Minimum lot frontage is 40 ft on a Town right-of-way and 50 ft on a county or state highway. The schedule sets THREE area limits: buildings may cover 30% of the lot, building FLOOR area may reach 50% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 60%. A building must stand 30 ft back from a residential district boundary line. A dwelling unit needs at least 500 sq ft of floor area, and an apartment 500 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Manchester Gateway Hamlet — MGH sets no single-family lot area; a townhouse needs 2,500 sq ft. Its Town-road front yard excludes townhouses and apartments. A building must also stand between 48.5 and 58.5 ft from the centre line of NYS Route 55. The Planning Board may approve a ZERO-foot rear yard. On a state or county road the front yard is 10 ft. Minimum lot frontage is 25 ft on a Town right-of-way and 25 ft on a county or state highway. The schedule sets THREE area limits: buildings may cover 75% of the lot, building FLOOR area may reach an unstated share of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 85%. A building must stand 25 ft back from a residential district boundary line. A dwelling unit needs at least 500 sq ft of floor area, and an apartment 500 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 50 ft.
Gateway Hamlet — GH sets no single-family lot area; a townhouse on public sewers needs 2,500 sq ft, and the Planning Board may approve six to twelve dwelling units per acre. It is the one district capped at two stories. On a state or county road the front yard is 10 ft. Minimum lot frontage is 25 ft on a Town right-of-way and 25 ft on a county or state highway. The schedule sets THREE area limits: buildings may cover 75% of the lot, building FLOOR area may reach an unstated share of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 85%. A building must stand 25 ft back from a residential district boundary line. A dwelling unit needs at least 500 sq ft of floor area, and an apartment 500 sq ft. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 2 stories as well as 35 ft.
General Business — Where both public water and sewer are available the Planning Board may allow a 20 ft front yard and a 70% total lot coverage in place of the figures here. On a state or county road the front yard is 45 ft. Lot width is tested twice: 150 ft along the building line, which is the figure recorded, and 50 ft at ANY point. Minimum lot frontage is 75 ft on a Town right-of-way and 225 ft on a county or state highway. A square of at least 100 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 20% of the lot, building FLOOR area may reach 40% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 50%. A building must stand 30 ft back from a residential district boundary line. An apartment needs at least 500 sq ft of floor area. Only finished year-round livable floor area counts, measured inside the exterior walls with a 7 1/2 ft ceiling; floor area above the ground floor counts only where a permanent inside stairway reaches it. Height is capped at 3 stories as well as 35 ft.
Commercial — On a state or county road the front yard is 45 ft. Lot width is tested twice: 150 ft along the building line, which is the figure recorded, and 50 ft at ANY point. Minimum lot frontage is 75 ft on a Town right-of-way and 200 ft on a county or state highway. A square of at least 100 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 30% of the lot, building FLOOR area may reach 60% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 70%. A building must stand 30 ft back from a residential district boundary line. Height is capped at 3 stories as well as 35 ft.
Industrial — Industrial is the one district set back 300 ft from a residential district boundary, and 165 ft from a state or county road against 75 ft from a Town road. On a state or county road the front yard is 165 ft. Lot width is tested twice: 200 ft along the building line, which is the figure recorded, and 50 ft at ANY point. Minimum lot frontage is 100 ft on a Town right-of-way and 200 ft on a county or state highway. A square of at least 200 ft on a side must fit on the lot — a buildable-square test independent of area and width, reducible under the open space subdivision rules at § 240-32. The schedule sets THREE area limits: buildings may cover 30% of the lot, building FLOOR area may reach 60% of the lot area, and TOTAL lot coverage — buildings, structures, outdoor deposit and paving together — may not exceed 60%. A building must stand 300 ft back from a residential district boundary line. Height is capped at 3 stories as well as 35 ft.
Size limits on record in La Grange
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 La Grange:
- Residential Flexible-DensityNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Residential Low-DensityNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Residential Moderate-DensityNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Residential Frank & SleightNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Town Center ResidentialNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Town ParkNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Overlook Planned DevelopmentNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Town Center BusinessNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- HamletNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Manchester Gateway HamletNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- Gateway HamletNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- General BusinessNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- CommercialNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
- IndustrialNot more than one bedroom; floor area at least 400 sq ft and not more than 35% of the dwelling's entire floor area
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 rentalsNo local short-term-rental law on record - which is not the same as permission. No local STR registration law as of Jun 2026. Dutchess County occupancy tax registration required. Verify with Town of La Grange Building Dept at (845) 452-1830 for any recent local law changes. Separate question from whether you can build the unit.
- Zoning codeecode360.com/6412940
- Building dept(845) 452-1830
Sizing up a specific parcel in La Grange?
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 La Grange runs $215–282/sq ft, about $390k–510k at 1,800 sq ft , plus roughly $4,495 for a conforming lot. See what it costs to build a house in La Grange.
ADU cost in nearby towns
All Dutchess County towns: Beacon (City) · Poughkeepsie (City) · Amenia · Beekman · Clinton · Dover · East Fishkill · Fishkill · Hyde Park · 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 La Grange: Can you build an ADU here? · Zoning for new construction · Dutchess County build cost
ADU cost in La Grange: common questions
How much does it cost to build an ADU in La Grange, NY?
An 800 sq ft accessory dwelling unit in Town of La Grange 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 La Grange?
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 La Grange?
Town of La Grange has 14 districts. 7 districts allow ADUs with occupancy restrictions, 3 do not. 4 districts have incomplete data - verify with the building department at (845) 452-1830. Check the specific address with the free ADU checker before you spend money on design.
Can I rent an ADU in La Grange short term?
No local short-term-rental law on record - which is not the same as permission for Town of La Grange. 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 La Grange 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) 452-1830 before relying on any answer. Sources: Offsite / Aldo cost engine (costEngine.js + constants.js); zoning dataset (municipalData.js).