Second Key is an ADU construction management firm serving Queens, Brooklyn, Staten Island, and the Bronx. We work with owners of one- and two-family homes to build legal, income-generating Accessory Dwelling Units on their property.
New York City's updated zoning rules now allow many homeowners to add an ADU. As a licensed general contractor, Second Key handles the full process: initial eligibility review, feasibility study, architect coordination, DOB permitting, and construction through Certificate of Occupancy.
Typical detached ADU projects run $300–$350 per square foot. The maximum ADU size in NYC is 800 square feet. Build time after permit approval is generally three to six months, though permitting timelines vary by project.
Homeowners work with us for three reasons: rental income from a permitted secondary unit, housing for family members on the same property, or increasing the long-term value of the home.
Second Key does not hand you off to a general contractor after the planning phase. We manage the build.