Second Key was founded by New York City residents who know firsthand how stressful and expensive construction can be. We simplify the process for homeowners who want to create beautiful additions that are built to code.

With decades of experience, we deliver quality work the right way - on time, on budget, and with no surprises. We specialize in detached, rear-yard ADUs and only work in New York City. Our model is simple, efficient, and designed to protect your time and money.