The five main ADU types — and which one suits your property.

Market
Written By AB

Most homeowners begin with one question: "Can I add an apartment?"


A better question is:
"Which type of ADU best fits my property?"

There are five common ADU types to consider.

  • 1.Internal ADU. Built within the existing home. Feasible if the house has enough legal floor area, proper access, and a layout that allows the new unit to be separated from the main living space.

  • 2.Basement or cellar ADU. Appealing because the space already exists, but it must meet strict safety standards. Under NYC's Appendix U, basement and cellar ADUs need a minimum clear ceiling height of 7 feet in habitable rooms — plus requirements for light, air, egress, and fire separation.

  • 3.Garage conversion. Sounds straightforward — but you need to confirm whether the garage is detached, attached, located in the rear yard, shared with a neighbor, or integrated into the main structure.

  • 4.Attached addition. Expands the existing house.

  • 5.Detached backyard ADU. Typically depends on lot depth, rear-yard requirements, access, and separation from the main house.

Don't get attached to one ADU idea too early. First, determine which type your property can realistically support.

Get your Free Score →
 

More Articles

News & Insights
The five main ADU types — and which one suits your property.
The five main ADU types — and which one suits your property.

Most homeowners begin with one question: "Can I add an apartment?" A better question is: "Which type of ADU best fits my property?"

There are five common ADU types to consider.

Your ADU Readiness Score is only the starting point.
Your ADU Readiness Score is only the starting point.

If you received an ADU Readiness Score, you have taken an important first step. The score can indicate whether your property has some of the basic conditions needed for an accessory dwelling unit — but it is not a final determination.

How NYC Homeowners Will Make $1,500–$3,500/Month in 2026
How NYC Homeowners Will Make $1,500–$3,500/Month in 2026

Many NYC homeowners are unaware that they already possess spaces within their properties that could legally generate significant monthly income. With property values and expenses rising, the opportunity to earn between $1,500 and $3,500 each month from unused areas presents a compelling solution.

Want to get involved in your community? JOIN THE CLUB!
Want to get involved in your community? JOIN THE CLUB!

We empower property owners, professionals, and policymakers with interactive courses, peer support, and open conversation, we aim to educate. This is a space to ask questions, share progress, and grow a movement rooted in practical impact and community driven change.

NYC embraces ADUs
NYC embraces ADUs

NYC has embraced the ADU. Queens, Brooklyn, Bronx, and Staten Island residents have a new opportunity to enhance their property value, help their family, and their community. Learn more about ADUs.

AB
Next

Your ADU Readiness Score is only the starting point.