ADU · Erie County

Can you build an ADU in Lancaster, NY?

Town of Lancaster has 8 districts. All districts prohibit ADUs. Check your address to confirm the district that applies to your parcel:

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What the Lancaster code says

Lancaster has no accessory apartment, accessory dwelling unit or in-law provision in any district, and a use the code does not specifically list is not allowed. The route to a second unit is MF, where two-family dwellings and multifamily housing are principal uses.

Conditions the code attaches:

In AR and R there may be no more than one principal structure per lot, so a detached second dwelling is out.
In AR, multiple principal farm structures are allowed where they are part of a farm operation, and no accessory structure is allowed on a lot without a principal structure.
All three residential districts take rooming and boarding of not more than three persons as an accessory use, which puts paying occupants in the house without creating a second dwelling unit.
MF is intended for higher-density development where public sewers are available, so sewer service is the practical gate.
GC takes every LC use and then states that no residential uses shall be permitted, with a narrow exception for funeral parlors and mortuaries with attendant or owner apartment.
MU mixes neighbourhood retail and service with residential above, as a mixed-use building type rather than an accessory unit.

What the Lancaster 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
Agricultural-Residential	3 ac	50 / 10 / 50 ft	35 ft	No
Single-Family Residential	0.34 ac	35 / 10 / 35 ft	35 ft	No
Multifamily Residential	0.069 ac	30 / 40 / 40 ft	35 ft	No
Mixed Use	1 ac	45 / 25 / 25 ft	35 ft	No
Light Commercial	1 ac	45 / 25 / 25 ft	35 ft	No
General Commercial	1 ac	60 / 15 / 15 ft	35 ft	No
Light Industrial	1 ac	30 / 15 / 15 ft	35 ft	No
General Industrial	1 ac	40 / 15 / 15 ft	35 ft	No

Agricultural-Residential - The three-acre minimum is per dwelling unit, so every dwelling unit on the lot needs three acres of its own. Neither side yard is a fixed number: each is the lesser of 10% of the lot width or 10 ft, and the two together the lesser of 25% of the lot width or 25 ft.

The 25% coverage cap is for the principal use, and an accessory use may add ten points on top
A house of two storeys or more needs 1,100 sq ft rather than 900 sq ft
A principal building other than a dwelling takes the greater of 15 ft or half its height, or the greater of 30 ft or its height where the yard abuts an agricultural, single-family or multifamily lot
Where half a block is already built, the front yard becomes the average of the existing houses on either side
An accessory building stops at 16 ft and 1,250 sq ft, and must sit 15 ft off a side line and 60 ft off the front; barns, silos and other farm accessory structures may reach 65 ft
A corner lot has two front yards, one facing each street, only one side yard, and the rear yard is whichever yard is opposite the front face

Single-Family Residential - The 15,000 sq ft is per dwelling unit, not per lot, and a public-sewer corner lot needs at least 15,625. Width is the figure sewer moves: 100 ft on public sewer, 125 ft on a public-sewer corner lot and 150 ft with no public sewer.

Neither side yard is a fixed number: each is the lesser of 10% of the lot width or 10 ft, and the two together the lesser of 25% of the lot width or 25 ft.
A principal building that is not a dwelling takes the greater of 15 ft or half its height, rising to the greater of 30 ft or its full height beside an agricultural, single-family or multifamily lot.
A house of more than one storey needs 1,200 sq ft rather than 1,000.
The 35% coverage cap is for the principal use and an accessory use may add five points; an accessory building stops at 16 ft and 750 sq ft.
Where an easement crosses the lot the yard is measured from the edge of the easement rather than from the property line, whichever is the more restrictive.
Where half a block is already built, the front yard becomes the average of the existing houses on either side.

Multifamily Residential - Two land figures apply at once and the larger one is the density driver: a lot must be at least 3,000 sq ft for each attached dwelling unit, but the scheme as a whole must devote 4,300 sq ft of gross land to each attached unit, excluding perimeter public streets.

A detached unit on its own lot falls back to the single-family district in full, and any other detached unit needs at least 7,500 sq ft with a 10 ft side yard.
Against a non-residential neighbour the side and rear yards fall to 20 ft.
Minimum dwelling size runs 400 sq ft for a studio, 640 for one bedroom, 760 for two and 1,000 for three, with a further 180 sq ft for each bedroom beyond that.
No main or longitudinal wall in a row of units may run more than 132 ft without a 90-degree offset of at least 10 ft, and no wall may aggregate more than 176 ft excluding offsets.
Principal structures must stand 30 ft apart, and the 40% coverage cap is for the principal use, with an accessory use adding five points.
A corner lot has two front yards, one facing each street, and only one side yard; the rear yard is whichever yard is opposite the front face.

Mixed Use, Light Commercial - The side and rear yards are priced by the neighbour: 25 ft against another non-residential lot, which is the figure shown, and 50 ft against a residential district.

Parking, loading and stacking areas stand 20 ft back from a dedicated street and the whole of that front area must be landscaped; they take 25 ft against a residential district and 10 ft otherwise.
Buildings on the same site must stand 30 ft apart, and every use except signs, landscaping and parking must be completely enclosed.
No coverage cap is set for this district.
Where half a block is already built, the front yard becomes the average of the existing buildings on either side.
A corner lot has two front yards, one facing each street, and only one side yard; the rear yard is whichever yard is opposite the front face.

General Commercial - The figures shown are the low tier against a non-residential neighbour; against a residential district the side and rear yards are 50 ft. Every yard steps up once the building passes 30 ft: the front from 60 ft to 75, the side and rear from 15 ft to 25, and from 50 ft to 75.

Parking, loading and stacking areas stand 20 ft back from a dedicated street, 25 ft from a residential district and 10 ft otherwise.
Buildings on the same site must stand 30 ft apart, and every use except signs, landscaping and parking must be completely enclosed.
No coverage cap is set for this district.
A corner lot has two front yards, one facing each street, and only one side yard; the rear yard is whichever yard is opposite the front face.

Light Industrial - Thirty-five feet is the by-right ceiling here, not 65: a building over 35 ft needs a special use permit, so the taller figure is reachable only through a discretionary approval.

Every yard steps up once the building passes 30 ft: the front from 30 ft to 75, the side and rear from 15 ft to 25 against a non-residential lot, and from 50 ft to 75 against a residential district.
The side and rear yards shown are the figures against a non-residential neighbour; against a residential district they are 50 ft.
Parking, loading and stacking areas stand 20 ft back from a dedicated street, 50 ft from a residential district and 10 ft otherwise.
Buildings on the same site must stand 30 ft apart, and all manufacturing or processing must be completely enclosed.
No coverage cap is set for this district.
A corner lot has two front yards, one facing each street, and only one side yard; the rear yard is whichever yard is opposite the front face.

General Industrial - Thirty-five feet is the by-right ceiling here, not 65: a building over 35 ft needs a special use permit, so the taller figure is reachable only through a discretionary approval.

Every yard steps up once the building passes 30 ft: the front from 40 ft to 75, the side and rear from 15 ft to 25 against a non-residential lot, and from 50 ft to 75 against a residential district.
The side and rear yards shown are the figures against a non-residential neighbour; against a residential district they are 50 ft.
Parking, loading and stacking areas stand 20 ft back from a dedicated street, 50 ft from a residential district and 10 ft otherwise.
Buildings on the same site must stand 30 ft apart, and all manufacturing or processing must be completely enclosed.
No coverage cap is set for this district.
A corner lot has two front yards, one facing each street, and only one side yard; the rear yard is whichever yard is opposite the front face.

ADUs vs. short-term rentals in Lancaster

Short-term-rental status not confirmed for Town of Lancaster. The short-term rental rules here are not confirmed: a local law is in progress but not confirmed adopted. Ask the building department whether it has since been adopted 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 minimum0.069–3 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityNational Grid territory.
Zoning codeecode360.com/35039171
Building dept(716) 683-9028

ADU FAQ — Lancaster, NY

Are ADUs allowed in Lancaster, NY?

Town of Lancaster has 8 districts. All districts prohibit ADUs. Check your address with the free ADU checker, or confirm with the building department at (716) 683-9028.

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

No. No district in Town of Lancaster permits an ADU, so there is no permit to apply for. Codes change, so verify with the building department at (716) 683-9028 before ruling it out.

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

Short-term-rental status not confirmed for Town of Lancaster. 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.

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What an ADU costs to build in Lancaster

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $200k–260k 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 Lancaster, priced by size.

How we know this

Sections analyzed: §§ 400-13 through 400-16 (Residential Districts) · § 400-14C and § 400-4 (Interpretation) · §§ 400-17 through 400-21
Districts confirmed: 8 of 8 — every mapped district.
Last reviewed: 2026-09-10
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 Lancaster: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Erie County · All Erie County towns

ADU information for Town of Lancaster is compiled from the municipal code (last reviewed 2026-09-10) 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 (716) 683-9028 before relying on any answer. Source: the Offsite / Aldo zoning dataset.