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Can I build an ADU, and does it pay?

Quick check against California ADU law, then cost, rent and how many years until it pays for itself.

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Allowed? Quick check vs state law
ADU law changes almost every year, and each city adds its own rules on top. Treat this as a first look, then confirm with the city planning counter.

Next steps

  2. Pull your lot's survey or plot plan. Mark the 4 ft side and rear lines, trees, and where the sewer line runs.
  3. Get 2–3 ADU builder quotes that include design, permits, utility hookups and sitework, not just the box.
  4. Paying with home equity? Run the numbers in the HELOC vs cash-out tool and talk to a lender before you sign a build contract.

Many people get this wrong: "An ADU will reassess my whole house." It won't. The county adds only the value of the new ADU to your tax bill. Your main house keeps its old Prop 13 value.

Ask Ken Watch 15-sec video

Email this ADU estimate to yourself

Ken can tell you what ADUs add to sale prices in your neighborhood. No spam.

Or text: 408-666-2825