A colorful map of New York with a couple of house graphic on top

Are you a New Yorker considering adding an accessory dwelling unit (ADU) to your home?

The prospect of creating a rental income stream or accommodating a growing family is undoubtedly enticing.

I’ll take you through what you need to know about building ADUs in New York. I’ll also cover the regulations governing the construction of ADUs in major NY cities. Keep reading!

The Definition of an ADU According to New York Laws

ADU construction in New York featuring wooden boards
ADUs in New York are attached or detached residential units for at least one person.

New York’s Senate Bill AB A4854 was introduced to streamline permitting, ensure generous size limits, and restrict fees your local agency could charge you to build an ADU on your property.

According to the legislation, an ADU in New York refers to a detached or attached residential dwelling unit with complete independent living facilities for one or more people. The unit must be on a lot with an existing or a proposed primary residence.

Finally, an ADU must have permanent provisions for eating, living, sleeping, and sanitation on the same lot.

By allowing ADUs in all zoned areas for single and multi-family use, the state can create much-needed housing for families, young professionals, and retirees.

New York’s ADU Construction Regulations

The zoning of your property will determine whether you can build an ADU on it.

As mentioned, although the state has standards that govern ADUs, local jurisdictions like cities and towns are allowed to set their own rules for the size, type, design, and use of ADUs on residential property.

As a general rule of thumb for ADUs across New York, local jurisdictions are expected to comply with these guidelines:

● All ADUs must be at least 200 square feet (18.58 square meters). Local authorities can’t demand a larger minimum.

● The maximum size of an ADU in the state should be 1,500 square feet (139.35 square meters), which offers space for three to four bedrooms.

● Regardless of local development rules, you can build an 800-square-foot (74.32-square-meter) attached or detached ADU. The ADU should have a 4-foot (1.22-meter) side and rear setbacks. This guideline encompasses the minimum lot size, floor-area ratio, and open space.

A point worth noting is that if you want to build an attached ADU, the ADU should be at most 50 percent of your primary residence’s square footage.

Alternatively, the attached ADU should be at most 600 square feet (55.74 square meters), regardless of your primary home’s size.

Accelerating the Adoption of ADU Units in New York

By providing grants to local government units and not-for-profit organizations committed to creating safe and quality ADUs, the state hopes to accelerate the adoption of code-compliant ADUs.

ADU units financed under the Plus One ADU Program are subject to local permits and may be stand-alone units on basement apartments, single-family lots, garage conversions, or other legal units.

The Plus One ADU Program finances these activities:

● Pre-development: Activities like environmental assessments, permitting, designing, appraisals, and other necessary due diligence for the project.

● Construction oversight: Overseeing all aspects of the construction process. This includes contractor bidding and selection, general construction coordination and oversight, compliance with local and state building codes, and payment preparations.

● Post-construction monitoring: Compliance monitoring activities like collecting annual compliance certificates confirming that the ADU is being used as intended and site visits to ensure appropriate ADU maintenance.

How to Know If You Can Build an ADU in New York

Indoor ADU construction with spotlights overhead
Contact your HOA, local government, or contractor to confirm if you can build an ADU in NY.

How can you confirm that your locality allows ADUs?

Here are some methods.

● Consult your local government: Your local government is in the best position to tell you if ADUs are allowed in your city. It shouldn’t take long to get this information from them, and they should also help with any relevant local zoning laws or regulations.

● Consult your homeowner’s association: If your home is part of a homeowner’s association, check if it allows ADUs. Depending on the homeowner’s association in your city, they may have their own rules regarding building an ADU. However, the law prohibits HOAs from declining ADU construction in some states.

● Check with a local architect or contractor: If you’re unsure of what requirements and regulations apply in your area, get help from an experienced local architect or contractor. They can point you in the right direction based on their experience.

● Do an online search: Check out the local building authorities, neighborhood associations, and other relevant sites to determine if ADUs are allowed in your area. Additionally, you can look for recent news articles or press releases from your city government on this subject matter.

Permits and Fees for ADUs in New York

ADU permits on approved lots in New York are issued ministerially. This means the city must approve or deny applications based on the applicable building codes defined by the state.

Moreover, the city has up to 60 days (from the day of receiving the application) to approve or deny it.

Fortunately, even if your plan is denied, you have 30 days to resubmit it.

The permit fee is at most $1,000.

ADU Rules and Regulations for New York’s Main Cities

Let’s take a look at the regulations for ADUs in some of New York’s main cities.

New York City

New York City skyline at sunset with pink, purple, and yellow colors
New York City allows ADUs on single-family lots.

The Department of Buildings and the NYC Housing Preservation and Development (HPD) has specific zoning rules for building ADUs.

The first requirement in NYC is that the ADU be located on single-family lots and meet all safety and building standards.

Also, the ADU can’t exceed 50 percent of your primary residence’s square footage.

According to the Department of Buildings, you can create an ADU in NYC in these ways:

● Turning a basement into a legal apartment

● Converting an attic into a legal apartment

● Turning a single-family house into two or three ADU units

Of course, all the above cases are subject to the state’s general building guidelines for safety.

According to NYC’s press secretary at the Department of Buildings, you can only add an ADU to your basements or backyards by submitting plans to the DOB.

After that, you should apply for a new certificate of occupancy.

The certificate of occupancy stipulates the legal use of the ADU and the type of permit it holds. It also confirms that the completed ADU adheres to all building rules and codes.

Appendix Q, which guides the construction of tiny houses, including ADUs in New York City, stipulates these requirements:

● There must be an egress roof access window based on Section R310.2 for rescue opening and emergency escape

● A ceiling height of at least 6 feet 8 inches (2032 mm) for habitable spaces

● A ceiling height of at least 6 feet 4 inches (1930 mm) for toilet rooms, bathrooms, and kitchens

● Obstructions like girders, lighting, ducts, and beams shall not extend below the stipulated ceiling heights

Town of Rochester

Rochester, New York overlooking the water with a reflection
Rochester ADUs need egress and ingress to meet building code requirements.

According to Chapter 140 of the Zoning Code of the Town of Rochester, all ADUs must adhere to habitable space requirements defined by the New York State Uniform Fire Prevention and Building Code.

Ingress and egress are among the main features your ADU must have to be in line with these building codes.

These features must enable safe and easy entrance into the unit.

All ADUs in the Town of Rochester are subject to requirements for residential building permits.

Therefore, you must secure a permit before embarking on the project to be on the safe side of the law.

You can get the building permit from the Town Board or Code Enforcement Officers in your area of jurisdiction.

Ensure you’re in one of the zoned districts permitted for ADU construction. These districts include AB-3, AR-3, R-1, R-2, R-5, B, and H.

A point worth noting is that for easy permitting, ensure the conversion or construction project clearly demonstrates that the ADU is secondary or incidental to the primary residence.

This way, your chances of getting a permit will be higher.

Finally, the law stipulates that ADUs shall never be used for commercial, industrial, or multifamily dwelling accessories.

Town of Amherst, New York

The Town of Amherst in New York has a Zoning Ordinance stipulating the requirements for constructing an ADU in the area.

The ordinance permits the construction of ADUs within a single-family detached dwelling, subject to the following guidelines:

● The ADU should only accommodate up to two members of the family occupying the primary dwelling. One of the occupants should be handicapped or at least 60 years old. Alternatively, one of the occupants should be incapacitated so independent housing is impossible.

● The ADU should not exceed 500 square feet (46.45 square meters).

● Permits for ADUs are valid for two years, after which they must be renewed periodically. The renewal is subject to satisfactory proof that the ADU is being used for its intended purpose.

Final Thoughts

Building an ADU in New York State can be daunting. However, you can make it happen with the right permits and understanding of the regulations and codes.

It’s important to note that these rules and regulations may change over time. Make sure you keep up-to-date with changes as they occur for your ADU to remain legal.

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