California ADU Loan Calculator
California homeowners finance more ADUs than any other state — and often pay the highest build costs in the country. Use this calculator to compare monthly payments on a HELOC, cash-out refi, construction-to-permanent, and DSCR loan against a realistic California ADU build cost. The break-even section shows how close typical California ADU rent comes to covering the monthly payment.
Enter your project details
Loan amount: $220,000
HELOC
Variable rate, interest-only draw option
Flexible line of credit. Only pay interest on what you draw.
Construction-Perm
Draws during build, converts to mortgage
Funds disbursed by milestone. Permanent loan activates at completion.
Cash-Out Refi
Replaces your current mortgage
Combines existing mortgage + ADU cost into one new 30-year loan.
Rent-coverage estimate
Typical ADU rent in the West Coast region runs about $2,600/mo. That covers roughly 147% of the featured HELOC monthly payment shown above.
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Active ADU financing programs in California
Local City ADU Incentives
waiverMany California cities (Los Angeles, San Diego, San Jose, Oakland) waive or reduce impact fees, school fees, or utility connection fees for ADUs. Check your municipality's ADU program for current offers. Note: the statewide CalHFA ADU Grant Program closed to new applications in December 2023 after all funds were allocated.
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ADU loan product comparison
| Product | Typical rate | Term | Best for |
|---|---|---|---|
| HELOC | 7.5–10.5% variable | 10 draw + 20 repay | Homeowners with 20%+ equity who want flexibility |
| Home Equity Loan | 7.3–10.3% fixed | 10–30 yr | Borrowers who want a fixed monthly payment |
| Cash-Out Refi | 7.5–8.5% fixed | 30 yr | Current mortgage rate already near market |
| Construction-Perm | 8.0–12.0% | 12–18 mo then 30 yr | Ground-up builds over $200K |
| DSCR | 8.5–12.0% | 30 yr | Investors qualifying on rent |
| RenoFi | 8.0–11.0% | 10–20 yr | Limited current equity, new-build ADUs |
Frequently asked questions
What is the best ADU loan in California?
For California homeowners with 20%+ equity, a HELOC or fixed home equity loan is typically the cheapest way to finance an ADU. For new-construction builds over $200,000, California lenders increasingly offer construction-to-permanent loans that fund in draws and convert to a 30-year mortgage at completion. Investors with a rental plan often use a DSCR loan that qualifies against projected ADU rent.
How much does an ADU cost to build in California?
Typical detached ADU builds in California land between $180,000–$450,000. A 750 sq ft two-bedroom unit in Sacramento usually falls mid-range, while high-end coastal builds push higher once soft costs, site prep, and utility hookups are counted.
Are there state-level ADU grants in California?
Active grant programs rotate frequently. We list the current state-level programs in the calculator above. Note: the CalHFA ADU Grant Program closed to new applications in December 2023 after all funds were allocated, so California homeowners should look to municipal fee waivers and lender-side incentives instead.
How long does ADU loan approval take in California?
HELOC and home equity loans typically close in 3–5 weeks. Construction-perm loans take 6–10 weeks because the lender must review plans, permits, and a draw schedule. Getting pre-approved before you finalize designs shaves weeks off the project timeline.
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Complete guide to every ADU loan product.
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