How to Finance an ADU in Southern California

An ADU is a major project, and how you finance it often shapes what you're able to build. Here are the financing paths Southern California homeowners use most often.

Home equity (HELOC or cash-out refinance)

For homeowners who've owned their property for several years, tapping existing equity is usually the cheapest and most straightforward option. A HELOC gives you a flexible credit line you draw from as construction costs come in, while a cash-out refinance replaces your existing mortgage with a larger one and gives you the difference in cash upfront. Which is better depends on your current mortgage rate — refinancing out of a low existing rate to fund a project is often less attractive than it was in past years, making a HELOC the more common choice for homeowners who locked in a low rate previously.

Renovation and construction loans

If you don't have enough equity yet to cover the full project cost, renovation-specific loan products like Fannie Mae's HomeStyle Renovation loan or an FHA 203(k) loan let you borrow against your home's projected value *after* the ADU is complete, not just its current value. These loans involve more paperwork and typically require working with a lender experienced in construction/renovation lending, but they can unlock financing that a standard home equity product can't.

Personal loans and contractor financing

For smaller-scope projects like a garage conversion, some homeowners use an unsecured personal loan or contractor-arranged financing. These typically carry higher interest rates than home-equity-based options, so they tend to make the most sense for smaller budgets or as a bridge while a HELOC or refinance is in process.

State and local assistance programs

California has, at various times, offered programs aimed at making ADU construction more accessible, most notably CalHFA's ADU Grant Program, which has provided grant funding toward pre-construction soft costs (design, permitting, impact fees) for eligible homeowners. These programs are subject to available funding and specific eligibility requirements and can open or close to new applicants, so check current availability directly with CalHFA or a participating lender before building it into your budget.

Choosing the right path for your project

The right financing choice depends heavily on how much equity you currently have, your existing mortgage rate, and your total project budget. Many homeowners find it worthwhile to get a written estimate from a licensed ADU contractor first — lenders offering renovation/construction loan products will typically want a contractor bid before finalizing loan terms, so getting quotes early through the "Get a Free Quote" form on this site can also help move your financing process forward.