# ADU Financing in California: How to Build & Finance an Accessory Dwelling Unit
California leads the nation in ADU construction. New state laws have streamlined permitting, and financing options have expanded significantly. Here's how to fund your ADU project.
What is an ADU?
An Accessory Dwelling Unit is a secondary housing unit on a single-family lot — a converted garage, backyard cottage, basement apartment, or addition above a garage. California law now allows at least one ADU on any residential lot, with streamlined permitting that bypasses many traditional barriers. ADUs typically cost $100,000-$400,000 to build depending on size, finish level, and whether it's a conversion or new construction.
Cash-Out Refinance
If you have significant equity in your primary home, a cash-out refinance replaces your existing mortgage with a larger one and gives you the difference in cash. With California home values often exceeding $800,000-$1,000,000+, many homeowners have $200,000+ in accessible equity. Advantages include one mortgage payment (instead of a first mortgage plus a separate ADU loan), potentially lower rates than construction or personal loans, and tax-deductible interest. The maximum LTV for a cash-out refinance is typically 80%.
HELOC (Home Equity Line of Credit)
A HELOC gives you a revolving line of credit secured by your home equity. You draw funds as needed during construction — paying interest only on what you've used. This is ideal for ADU projects because construction costs are paid in stages (foundation, framing, electrical, finish). HELOCs typically allow up to 85-90% combined LTV. Rates are variable but often lower than construction loans.
Construction Loans
A construction-to-permanent loan finances the build and then converts to a standard mortgage upon completion. This is the best option if you don't have enough equity for a cash-out refi or HELOC. The lender funds draws based on construction milestones verified by an inspector. After completion, the loan converts to a 30-year fixed mortgage. Save Financial works with lenders who finance ADU construction specifically.
CalHFA ADU Grant Program
CalHFA offers grants of up to $40,000 for ADU construction through the ADU Grant Program. The grant can be used for pre-development costs (plans, permits, soil tests, impact fees) and is forgivable. Eligibility is based on income limits that vary by county. This grant can be combined with any of the financing methods above.
Rental Income from Your ADU
An ADU can generate $1,500-$4,000/month in rental income depending on location and size. This income can help qualify for the construction financing (some lenders count projected rental income) and provides ongoing cash flow that often covers the loan payment with surplus. In high-demand areas like Los Angeles, the Bay Area, and coastal Orange County, ADUs are among the best ROI home improvements in California.
ADU as Investment Strategy
Many California homeowners are building ADUs specifically as investment vehicles. The construction cost of $150,000-$300,000 can add $200,000-$500,000+ in property value while generating $2,000-$4,000/month in rental income. This is a better return than most traditional investments, secured by real estate in the strongest housing market in the country.
Save Financial provides ADU-specific financing consultations. Call (888) 703-1840 to discuss your project with a specialist who understands California ADU regulations and financing options.