I’m Michael DiVita — DRE #01372066 | NMLS #241655, DiVita Home Finance (DRE #01818285 | NMLS #323700), Tiburon, CA. I’ve been in California mortgage lending since 2000 and founded DiVita Home Finance in 2007. Marin County homeowners are sitting on some of the highest home equity in California — ADU financing is one of the smartest ways to put it to work. Call (800) 239-1103.
Marin County homeowners have accumulated substantial home equity, and many are putting it to work by adding accessory dwelling units. An ADU can generate $2,500–$4,500/month in rental income in most Marin cities, adds meaningful appraised value to the property, and creates housing for family members or long-term tenants. DiVita Home Finance helps Marin homeowners find the most cost-effective financing structure for the build — without unnecessarily disturbing a low existing mortgage rate.
Marin County ADU Market Overview
Cities and towns across Marin have adopted ADU-friendly permitting aligned with California state law. Garage conversions, detached backyard cottages, and attached additions are all permitted in single-family zones throughout the county. Typical permit timelines in Marin run 3–6 months depending on the municipality and project complexity. Mill Valley and Tiburon tend to be more thorough in review; San Rafael and Novato move somewhat faster. Construction costs for a Marin ADU typically run $150,000–$350,000 depending on size, finishes, and site conditions.
ADU Rental Income Estimates: Marin County (2026)
In Mill Valley and Tiburon, a detached 1-bedroom cottage typically rents for $3,200–$4,500/month. In San Rafael, a garage conversion studio runs $1,800–$2,600/month. In Fairfax and San Anselmo, an attached in-law unit runs $2,200–$3,200/month. In Novato, a detached 2-bedroom ADU can achieve $2,800–$3,800/month. These rental income figures, once documented with a signed lease, can be used to offset the new mortgage payment in DTI calculations for the financing — making the ADU partially self-funding from a qualification standpoint.
Financing Options for Marin ADU Projects
Because Marin home values are high, most homeowners have substantial equity — often enough to fund an ADU without touching their existing low-rate first mortgage. A HELOC is the most popular choice for rate-protected borrowers: if your home is worth $1,800,000 and your mortgage balance is $400,000, a lender may allow a HELOC up to 80% combined LTV — giving you access to up to $1,040,000 in a revolving credit line. Most Marin ADU builds cost $150,000–$350,000, well within reach. For homeowners without a low existing rate, a cash-out refinance into a new first mortgage can be the most streamlined option — one loan, one payment, fixed rate. I compare the full cost of both structures for every client before making a recommendation. For self-employed Marin homeowners with strong cash flow but tax return write-offs, bank statement ADU loans qualify you on 12–24 months of deposits rather than taxable income, opening up larger loan amounts.
Frequently Asked Questions — ADU Loans in Marin County
Can I use ADU rental income to qualify for the financing?
Yes — once the ADU is completed, permitted, and rented, the documented rental income can be used to qualify for a refinance into permanent financing. Fannie Mae and Freddie Mac allow up to 75% of the ADU rental income to offset the mortgage payment in DTI calculations, with a signed lease and rental history. This is particularly powerful as an exit from a construction loan or interim HELOC: the ADU income improves your DTI and the higher post-ADU appraised value improves your LTV, often allowing better rates on the permanent loan.
Should I use a HELOC or cash-out refinance to build my Marin ADU?
The right answer depends on your existing mortgage rate. If you bought or refinanced between 2020 and 2022 at 2.5%–3.5%, a HELOC preserves that rate on your first mortgage while giving you a separate line for the ADU build. A cash-out refinance would roll everything into one new loan at today’s rates — costing significantly more per month. If your existing rate is already at or near current market rates, the cash-out refi simplicity may be worth it. I run both scenarios side-by-side with your actual numbers to show the 5-year and 10-year cost difference before you decide.
What is the maximum HELOC I can get for an ADU in Marin County?
Most lenders allow combined LTV of 80–85% on a Marin County property. On a $2,000,000 home with a $600,000 existing mortgage, an 80% CLVT allows a total of $1,600,000 in liens — meaning up to $1,000,000 in HELOC availability. Most Marin ADU builds cost $150,000–$350,000, so even a home with a significant existing mortgage can typically access enough HELOC to fund the full build. For properties valued over $2M, I have access to jumbo HELOC products with higher combined LTVs than standard bank programs offer.
Talk to Michael Directly
DiVita Home Finance | Tiburon, CA | In lending since 2000, founded DiVita Home Finance in 2007. Michael DiVita DRE #01372066 | NMLS #241655. Company DRE #01818285 | NMLS #323700.
💬 Text: (310) 849-9124
