What it costs to build an ADU in Montgomery, NY

Residential Agriculture — One-Family Residences - Only a single-family house is permitted here; a two-family house is not, and converting an existing house to a multifamily one needs a special use permit. The two-acre minimum is the same with or without central water or sewer.

• A lot on a state or county road must be at least two hundred and fifty feet wide.
• The lot area is a requirement per dwelling unit, so a second unit doubles the land.
• A side yard on the street side of a corner lot must be at least seventy-five feet.
• An accessory building may not cover any of the required rear yard, may not exceed twenty-five feet in height there, and must stand at least ten feet from any lot line.
• No lot for a single-family detached dwelling may be narrower than forty feet at any point between the front line and where lot width is measured.
• Coverage counts main and accessory buildings together.

Residential Agriculture — One- and Two-Family Residences - The figures shown apply more than a mile from a business district. Within half a mile, a lot with central water and sewer needs at least sixteen thousand three hundred and thirty-five square feet and at least a hundred feet of width, with coverage up to twenty-five percent.

• Within a mile, a lot needs at least 43,560 square feet unserviced, thirty-two thousand six hundred and seventy with water or sewer, and twenty-one thousand seven hundred and eighty with both.
• Within a mile, coverage may reach twenty percent; a lot needs at least a hundred and twenty-five feet of width and yards of at least forty front, twenty a side with forty for the pair, and forty rear.
• Closer still, inside half a mile, an unserviced lot needs at least thirty-two thousand six hundred and seventy square feet, or twenty-seven thousand two hundred and twenty-four with either service.
• Within half a mile, yards must be at least thirty-five front, fifteen a side with thirty for the pair, and thirty-five rear.
• Distance runs from the nearest lot line to the nearest Crossroads, B-1, B-2 or B-3 district, or a Village of Montgomery or Village of Walden business district.
• A planned adult community, a single-family attached dwelling and the conversion of an existing house to multifamily each need a special use permit.

Multifamily - Nothing may be built here without both central water and central sewer. The land figure applies per dwelling unit, so a ten-unit building needs fifty thousand square feet.

• A multiple dwelling or a single-family attached dwelling needs a special use permit; a one-family or two-family house is permitted by right.
• A two-family residence may take the per-unit land requirement down to eighty-five percent of it.
• The side yards may total fifteen feet, so a building may sit ten feet from one line and five from the other.
• A side yard on the street side of a corner lot must be at least twenty-five feet.
• An accessory building may cover up to thirty-five percent of the required rear yard, stand up to twenty feet high there, and must be at least five feet from any lot line.
• Coverage counts main and accessory buildings together.

Mobile Home Court - A licensed mobile home court needs a special use permit, and the permit standard requires a site of not less than five acres. Land per dwelling unit falls to eighteen thousand square feet with central water or sewer and twelve thousand with both.

• Individual spaces must be at least two thousand square feet and thirty feet wide, and the spaces must average at least three thousand square feet and forty feet.
• Initial development must cover at least two acres and each later addition at least one.
• Interior roadways must be paved and at least twenty feet wide, with curbs or gutters and two access drives to the public street.
• All mobile homes and accessory structures must be at least thirty feet apart, and no trailer may be more than a hundred and fifty feet from a refuse collection point.
• Sewage disposal and water supply need State Health Department approval, and the site needs a development plan by a licensed professional engineer.
• Coverage counts main and accessory buildings together.

Mobile Home Park — Age-Restricted - This floating district is reachable only on a special use permit, and the figures shown size the overall site plan, not individual lots; the park may not be subdivided into lots at all.

• Land per dwelling unit falls to eighteen thousand square feet with central water or sewer and twelve thousand with both.
• Occupancy is restricted to age fifty-five and over, with at least one resident aged fifty-five or more in every unit and no occupant under nineteen.
• The owner must certify compliance to the Code Enforcement Officer before the first of June each year, on an attorney's or licensed engineer's inquiry made within the previous forty-five days.
• Open space the Planning Board requires must be fixed in a conservation easement, approved by the Municipal Attorney and recorded with the Orange County Clerk, before the first building permit.
• Coverage counts main and accessory buildings together.

Regional Commercial - A house is not permitted; the only dwellings are a unit over or behind a first-floor commercial use, on a special use permit, and a caretaker's or owner's unit on site plan approval.

• Except by special use permit of the Town Board, access from Maple Avenue is limited to agricultural or normal residential purposes, other than within a thousand feet of NYS Route 17K.
• No halving of the front yard is available here; the fifty feet stands.
• A side yard on the street side of a corner lot must be at least twenty-five feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

Community Commercial - The Planning Board may cut the front yard in half, to twenty-five feet, at site plan approval where no parking is proposed in the front yard and the reduction suits the area's rural character.

• The reduction is discretionary, not an entitlement; the fifty-foot front yard binds until the Board grants it.
• No house is permitted; the only dwelling is a caretaker's or owner's unit, and it needs a special use permit.
• A side yard on the street side of a corner lot must be at least twenty-five feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

Tourist Commercial - A one- or two-family house here is held to the two-acre agricultural standard, not the lot minimum shown. The Planning Board may cut the front yard in half, to twenty-five feet, where no parking is proposed in the front yard and the reduction suits the area's rural character.

• The front-yard reduction is discretionary, taken at site plan approval; the fifty-foot front yard binds until the Board grants it.
• A side yard on the street side of a corner lot must be at least twenty-five feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

Crossroads Commercial Overlay - This is an overlay: the figures shown apply only to uses the underlying district does not already permit. Where the underlying district permits a use, its own bulk requirements govern instead.

• The Planning Board may cut the front yard in half, to twenty-five feet, at site plan approval where no parking is proposed in the front yard and the reduction suits the area's rural character.
• The reduction is discretionary, not an entitlement; the fifty-foot front yard binds until the Board grants it.
• A side yard on the street side of a corner lot must be at least twenty-five feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

General Industry - Parcels fronting on Bracken Road take a sixty-foot front yard instead of seventy-five, and a side yard on the street side of a corner lot must be at least seventy-five feet.

• Composting, recycling, handling and recovery facilities and biomass gasification-to-energy facilities take their lot area and bulk from a separate table graded by intensity of use, at § 235-7.4.
• Except by special use permit of the Town Board, access from Maple Avenue is limited to agricultural or normal residential purposes, other than within a thousand feet of NYS Route 17K.
• No house is permitted; the only dwelling is a caretaker's or owner's unit on site plan approval.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

Airport Industry - The figures shown apply to industrial uses. A dwelling is held to the two-acre agricultural standard, and a single-family house needs a special use permit.

• Other uses, neither industrial nor residential, need at least twenty thousand square feet and a hundred and fifty feet of width, with up to thirty percent coverage and forty feet of height.
• Those uses need yards of at least fifty front, twenty to a side with forty for the pair, and thirty rear.
• A side yard on the street side of a corner lot must be at least fifty feet.
• A caretaker's or owner's dwelling unit is available on site plan approval.
• Agriculture and farm uses need at least three acres.
• Coverage counts main and accessory buildings together.

Tech Industry - No ordinary house is permitted; the only dwelling is a caretaker's or owner's unit on site plan approval, and any residential use allowed is held to the two-acre agricultural standard rather than the lot shown.

• A side yard on the street side of a corner lot must be at least fifty feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.

Business Park - This is a floating district: land is in it only once the Town Board places it on a parcel. No dwelling of any kind is permitted, not even a caretaker's unit.

• No more than one building in four may be designed as a non-intensive warehouse.
• A side yard on the street side of a corner lot must be at least fifty feet.
• Agriculture and farm uses need at least three acres.
• An accessory building's setback from a lot line is the full district yard, not a reduced figure.
• Coverage counts main and accessory buildings together.