7 Key Costs to Expect When Building a California ADU in 2026 – Updating

ADU next to a Pool remodeled by Better Together Builders

With over 80,000 ADU permits issued statewide since 2016, California is in the middle of an ADU boom. But you deserve transparent numbers before you break ground—so let’s get into what it really costs to build an accessory dwelling unit, including hidden fees, cost-saving tips, and real price ranges.