Transforming NYC Spaces into Functional ADUs

Trusted ADU Experts
for NYC Homeowners

We help New York City property owners turn underused space into beautifully designed ADUs (Accessory Dwelling Units), adding value, comfort, and opportunity to their homes. From the first feasibility check to the final Certificate of Occupancy, our expert team is by your side through every step of the process. In the City That Never Sleeps, we don’t rest until your ADU feels like home.

Second Key provides a full-service, one-contract solution that includes permitting, design and construction. Send us your address and we'll provide a complimentary ADU assessment to show you what’s possible.

Make Every Square Foot Count
Start Your ADU Journey Today!

A Seamless Process

  • Feasibility & Planning

    Wondering if your New York City property is suitable for an ADU? Request a free ADU assessment by filling out the form here. We’ll help you understand your property’s potential and what type of Accessory Dwelling Unit you can build in compliance with NYC zoning laws.

    Our job is to make the process easy to understand and stress-free to begin.

  • Financing

    We assist you in the budgeting process and connect you with lending partners familiar with ADU construction in New York.

    Pre-approval for construction loans is often easier than homeowners expect, helping you secure funding quickly and confidently for your project.



  • Design, Permit, & Build

    Once you're ready, we’ll help finalize your ADU design, submit plans, and prepare your site for construction. Choose from pre-designed layouts with clear pricing or collaborate with our architects for a custom unit.

    Our team of architects, engineers, and contractors manages everything in-house, ensuring your project stays organized and on schedule. Most projects are ready for move-in within six months after permitting.

    Get started today.