Vetted ADU Builders in California

Frequently Asked Questions

How do I verify an ADU contractor's license in California?

Use the free CSLB "Check a License" tool at cslb.ca.gov. Enter the license number and confirm the status reads ACTIVE, the classification fits an ADU (usually Class B General Building), a bond is on file, and workers' comp is current. California law requires the license number to appear on all ads and contracts — every builder we list in California is verified against exactly these criteria.

How much does it cost to build an ADU in California?

The statewide median ADU runs about $150,000, and roughly 71% of California ADUs cost under $200,000. Garage conversions are the most affordable path, while a custom detached unit is the most expensive. Request an intro to a verified builder for a fully itemized fixed-price quote based on your actual lot and design.

Will building an ADU raise my property taxes in California?

No, not your whole property — this is a common misconception. California only reassesses the newly built ADU, typically at about 1% of its value per year, while your existing home keeps its original Proposition 13 basis and is not reassessed. So you pay incremental tax on the new unit only, not a full reassessment of everything you own.

Is the $40,000 CalHFA ADU grant still available in California?

No. The CalHFA $40,000 ADU Grant for pre-development costs is currently paused and out of funds — the last round was fully allocated in December 2023 with no confirmed relaunch. It may reopen if the state appropriates new funding, so verify the live status at calhfa.ca.gov before counting on it. Most California homeowners build without it, using home equity, savings, or renovation loans.