ADU · Westchester County

Can you build an ADU in Larchmont, NY?

Village of Larchmont has 11 districts. All districts prohibit ADUs. Check your address to confirm the district that applies to your parcel:

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What the Larchmont code says

An accessory apartment is not a permitted use in any Larchmont district: R-30, R-20, R-15, R-12.5, R-10, R-7.5, R-5, MF, W, RB or RC. A use absent from a district's enumerated lists is not available there (§ 381-3A).

Conditions the code attaches:

In R-30, R-20, R-15, R-12.5, R-10, R-7.5 and R-5 the resident family may take no more than two boarders or roomers, which creates no separate dwelling unit and no independent cooking facilities.
Larchmont has no two-family dwelling use.
MF permits multifamily dwellings (§ 381-39C), boardinghouses and rooming houses as principal uses, not as units subordinate to a house.
In R-7.5 a townhouse development takes a special permit under § 381-51B, but only if approved by the Board of Trustees.

What the Larchmont code indicates by district

The table below shows how each district treats ADUs, alongside the lot and setback standards that govern a second unit. District boundaries and conditions vary, so treat this 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 District	0.69 ac	30 / 12 / 50 ft	30 ft	No
One-Family Residence District	0.46 ac	30 / 12 / 40 ft	30 ft	No
One-Family Residence District	0.34 ac	30 / 10 / 30 ft	30 ft	No
One-Family Residence District	0.29 ac	30 / 10 / 30 ft	30 ft	No
One-Family Residence District	0.23 ac	30 / 10 / 25 ft	30 ft	No
One-Family Residence District	0.17 ac	30 / 10 / 25 ft	30 ft	No
One-Family Residence District	0.11 ac	30 / 6 / 25 ft	30 ft	No
Multifamily Residence District	0.034 ac	20 / 15 / 40 ft	30 ft	No
Retail Business Commercial District	0.023 ac	10 / - / 15 ft	25 ft	No
Retail Center Commercial District	0.023 ac	- / - / 15 ft	25 ft	No
Waterfront Coastal Zone District	1.15 ac	30 / 12 / 50 ft	30 ft	No

One-Family Residence District, One-Family Residence District - The 30 ft front yard is a maximum as well as a minimum: for a one-family dwelling the front and side-front yard may be no deeper than the average of the nearest four occupied lots in the same block on the same side of the street, where that average is less (§ 381-33A).

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter, measured from the lower of existing or proposed grade (§ 381-34A).
A sky-plane applies as well: at the minimum required side and rear setback line the height may not exceed 20 ft, rising 2 ft for each extra 1 ft of setback (§ 381-34C).
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 5% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
The 1,500 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 2,100 sq ft.

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter, measured from the lower of existing or proposed grade (§ 381-34A).
A sky-plane applies as well: at the minimum required side and rear setback line the height may not exceed 20 ft, rising 2 ft for each extra 1 ft of setback (§ 381-34C).
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 5% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
The 1,000 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 1,500 sq ft.

One-Family Residence District - The 30 ft front yard is a maximum as well as a minimum: for a one-family dwelling the front and side-front yard may be no deeper than the average of the nearest four occupied lots in the same block on the same side of the street, where that average is less (§ 381-33A).

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter, measured from the lower of existing or proposed grade (§ 381-34A).
A sky-plane applies as well: at the minimum required side and rear setback line the height may not exceed 20 ft, rising 2 ft for each extra 1 ft of setback (§ 381-34C).
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 6% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
The 1,000 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 1,500 sq ft.

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter. A sky-plane caps height at 20 ft at the minimum side and rear setback line, rising 3 ft for each extra 1 ft of setback.
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 6% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
The 800 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 1,100 sq ft.
A townhouse development takes a Board of Trustees special permit under § 381-51B, and the district publishes no by-right townhouse standards.

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter. A sky-plane caps height at 20 ft at the minimum side and rear setback line, rising 3 ft for each extra 1 ft of setback.
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 8% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
The 700 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 1,000 sq ft.

Multifamily Residence District - The 1,500 sq ft lot area is land per family, not a conforming lot for a multi-unit building: the lot has to carry 1,500 sq ft for every family in it. A one-family dwelling in MF instead needs a lot of at least 5,000 sq ft and 50 ft of width.

A one-family dwelling's yards are 15 ft front, 6 ft on one side and 14 ft combined, and 35 ft rear, with a 12 ft side-front yard.
Accessory buildings keep 5 ft from the side and rear lot lines, may not stand in a front, side or side-front yard, and are capped at 16% coverage against the principal building's 35%.
The 700 sq ft minimum first-story area applies at every story count here.
A sliding lot coverage limit keyed to the lot's actual area applies on top of the 35% building coverage (§ 381-38A).
Height is also subject to the building height and shape rules of § 381-34.

Retail Business Commercial District - The 1,000 sq ft lot area is land per family, not a conforming lot for a multi-unit building: the lot has to carry 1,000 sq ft for every family in it. The figures shown are otherwise the nonresidential case.

A multifamily building here follows its own standards: a 40 ft rear yard, 30 ft and 2 1/2 stories of height, 35% coverage and a 15 ft side-front yard.
The livable area for a unit in that multifamily case is at least 700 sq ft as an average across the units, not a floor for each one.
A side yard on any side abutting a residence district must be at least 15 ft; the schedule prints only the 30 ft both-sides figure otherwise.
In Block 614 on Chatsworth Avenue the front yard is 8 ft instead of 10 ft.
Accessory buildings in the multifamily case are capped at 16% coverage.
Height is also subject to the building height and shape rules of § 381-34.

Retail Center Commercial District - The 1,000 sq ft lot area is land per family, not a conforming lot for a multi-unit building: the lot has to carry 1,000 sq ft for every family in it. The figures shown are otherwise the nonresidential case.

A public-amenity-supplemented mixed-use development follows its own schedule under a Village Board special permit: a lot of 10,000 sq ft, 40 ft wide, and zero front, side and rear yards (§ 381-51N).
Within that permit the 50 ft height, four stories and 100% coverage are maximums the Village Board sets case by case, measured from existing grade along the Chatsworth Avenue frontage.
A side yard on any side abutting a residence district must be at least 15 ft, and in Block 614 on Chatsworth Avenue the front yard is 8 ft.
No multifamily standards are stated for RC: the footnote that carries them names only the RB district, though multifamily is a permitted use here (§ 381-26A(7)).
Height is also subject to the building height and shape rules of § 381-34.

Waterfront Coastal Zone District - The 30 ft front yard is a maximum as well as a minimum: for a one-family dwelling the front and side-front yard may be no deeper than the average of the nearest four occupied lots in the same block on the same side of the street, where that average is less (§ 381-33A).

A side-front yard of 30 ft is also required.
A second lot coverage limit keyed to the lot's actual area applies on top of the building coverage shown, from 55% at 3,000 sq ft down to 35% at 40,001 sq ft and above (§ 381-38A).
A one-family residence may not exceed 30 ft at any point around its perimeter. A sky-plane caps height at 20 ft at the minimum side and rear setback line, rising 2 ft for each extra 1 ft of setback.
An accessory building must be at least 5 ft from the side and rear lot lines, may cover 5% of the lot, and may not stand in the front, side or side-front yard (§ 381-32).
On the Yacht Club, Shore Club and Manor Park parcels the principal uses are parks, beaches and private membership clubs; a one-family dwelling needs a Board of Trustees special permit (§ 381-51E).
The 1,500 sq ft minimum is first-story floor area for a house of 2 to 2 1/2 stories; at one story the first story must be 2,100 sq ft.

ADUs vs. short-term rentals in Larchmont

No local short-term-rental law on record - which is not the same as permission for Village of Larchmont. The Village of Larchmont has no local short-term rental law, and that is not the same as permission. Confirm with the building department before counting on the use. These are separate questions from whether you can build an ADU — a unit you're allowed to add isn't automatically one you're allowed to rent nightly, so check both.

Good to know

Residential lot minimum0.034–0.69 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityCon Edison territory.
Zoning codeecode360.com/LA0851
Building dept(914) 834-4349

ADU FAQ — Larchmont, NY

Are ADUs allowed in Larchmont, NY?

Village of Larchmont has 11 districts. All districts prohibit ADUs. Check your address with the free ADU checker, or confirm with the building department at (914) 834-4349.

Do I need a special permit for an ADU in Larchmont?

No. No district in Village of Larchmont permits an ADU, so there is no permit to apply for. Codes change, so verify with the building department at (914) 834-4349 before ruling it out.

Can I use an ADU as a short-term rental in Larchmont?

No local short-term-rental law on record - which is not the same as permission for Village of Larchmont. ADU occupancy and short-term-rental rules are separate: an ADU you can build isn't automatically one you can rent nightly. Confirm both before you count on STR income.

Run the free ADU check for your parcel →

What an ADU costs to build in Larchmont

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $235k–310k at a standard finish, and the per-square-foot rate comes in above a full house because the kitchen, bath, panel and heating plant cost the same either way. See the full cost to build an ADU in Larchmont, priced by size.

How we know this

Sections analyzed: Ch. 381 Art IV Use and Dimensional Regulations §§ 381-13 to 381-26; § 381-3A; § 381-39C (MF); § 381-51B (townhouses)
Districts confirmed: 11 of 11 — every mapped district.
Last reviewed: 2026-09-28
Not covered here: Overlay districts, the zoning map, and any conditions attached to an individual parcel. Size limits and owner-occupancy terms sit in the code section above, not in this summary.

More on Larchmont: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Westchester County · All Westchester County towns

ADU information for Village of Larchmont is compiled from the municipal code (last reviewed 2026-09-28) and provided for decision-support only — not legal or architectural advice. ADU eligibility, size, owner-occupancy and permit conditions vary by district and often carry exceptions; verify with the building department at (914) 834-4349 before relying on any answer. Source: the Offsite / Aldo zoning dataset.