New York ADU Laws & Garage Conversion Guide

What Is an ADU?

An accessory dwelling unit (ADU) is a secondary, self-contained living space on a single-family lot — think a converted garage, a basement apartment, or a backyard cottage. ADUs are one of the most popular ways to add livable, rentable, or multi-generational space to a New York property.

Are ADUs Legal in New York?

New York State has taken steps to expand homeowner access to ADUs, and New York City has its own zoning rules that govern what can be built where. Whether your project is allowed depends on your zoning district, lot size, parking, and whether the unit is attached or detached. The rules are detailed and change over time, so the right first step is a zoning and feasibility review.

Common ADU & Garage-Conversion Paths

• Garage conversion — turning an attached or detached garage into livable space.
• Basement apartment — legalizing or creating a basement dwelling (subject to strict NYC rules on ceiling height, egress, and waterproofing).
• Detached backyard cottage — a new structure, where zoning allows.
• Interior conversion — carving an in-law suite or accessory unit out of existing square footage.

What We Handle

• Zoning and feasibility review for your specific lot.
• Permits and DOB filings for the conversion or new construction.
• Structural, plumbing, electrical, and egress work done to code.
• Waterproofing and ventilation — critical for basement and below-grade units.

ADU rules evolve. Before planning your budget, confirm current local and state requirements with us and the DOB. Request a feasibility consultation to find out what's possible on your property.