Research · Housing Policy · ADUs

Accessory Dwelling Units in New York City

A policy overview of the as-of-right path, and where in the city it reaches.

NYC ADUsAs-of-rightZoningHousing policy

The as-of-right question

Accessory dwelling units add housing inside neighborhoods that already exist, without new land or new infrastructure. In New York City, the decisive question is not whether an ADU is a good idea, but whether it is permitted as-of-right: allowed directly by the zoning resolution, with no special permit, variance, or discretionary review.

As-of-right status is what makes an ADU realistic for an ordinary homeowner. It turns a long, uncertain approvals process into a straightforward permit, and it is largely determined by two things: the zoning district and the building type.

This page is an illustrative policy overview. The values shown are simplified for demonstration and are not a substitute for the zoning resolution or professional guidance.

Where it reaches

The map highlights housing across the five boroughs that is Building Type A1 within R2, R3, and R4 zoning districts, the low-density stock most directly touched by as-of-right ADU rules.

Map of New York City highlighting Building Type A1 housing in R2, R3, and R4 zones — Building Type A1 housing in R2, R3, and R4 districts across New York City. Highlighted parcels mark the low-density housing most relevant to the as-of-right ADU pathway.

As-of-right vs. discretionary

Two paths lead to an ADU. Only one is practical at the scale of a whole city.

Path A

As-of-right

Permitting: Allowed directly by the zoning resolution
Approvals: No special permit, variance, or board review
Timeline: Faster, cheaper, and more predictable
Eligibility: Set by zoning district and building type

Path B

Discretionary

Permitting: Requires a special permit, variance, or authorization
Approvals: Reviewed by City Planning or the Board of Standards and Appeals
Timeline: Longer, with a less certain outcome
Eligibility: Often the only path outside eligible districts

By zoning district

Select a district to see how the as-of-right ADU rules shift across the low-density zones shown on the map. A simplified mock for illustration.

R2 · R2

Single-family detached, Building Type A1

Predominant building type: A1, one-family detached
As-of-right ADU: Interior conversion or a detached rear-yard unit
Unit size: Capped and subordinate to the main house
Owner occupancy: Generally required
Parking: Not required near transit
Approval: As-of-right, with no special permit or variance

R3 · R3

Low-density one- and two-family

Predominant building type: A1 and small two-family homes
As-of-right ADU: Interior, attached, or detached unit
Unit size: Capped by floor area
Owner occupancy: Generally required
Parking: Limited or waived near transit
Approval: As-of-right within district limits

R4 · R4

Low-density, some attached and multifamily

Predominant building type: A1, attached, and small multifamily
As-of-right ADU: Interior or attached unit, with more flexibility
Unit size: Larger caps than R2 and R3
Owner occupancy: May vary by configuration
Parking: Reduced requirements
Approval: As-of-right, subject to bulk rules

Illustrative values for demonstration only. Confirm current requirements against the NYC Zoning Resolution and Department of Buildings.