Financing an ADU with your home's equity

ADU financing with home equity means taking a second mortgage against the house you already own and using it to build the unit. A HELOC for ADU construction (a home equity line of credit) lets you draw as each stage of the build comes due. A home equity loan for ADU costs hands you a lump sum at a fixed rate. Either way, your first mortgage stays exactly as it is, and the loan is sized on your home's current value, since the ADU does not exist yet. The calculator below shows roughly how much equity you could reach today.

Why ADUs and home equity go together

Most home projects cost money and give back comfort. An accessory dwelling unit, a self-contained second home on your lot with its own kitchen, bath and entrance, gives back cash. It can house a parent, an adult child, or a tenant paying market rent. You are borrowing to build something that produces income, and the income can be pointed straight at the loan.

Home equity is the natural source for that borrowing. Homeowners who have been in place long enough to have a usable backyard usually have equity to match, and a first mortgage rate they do not want to give up. A second lien, whether a HELOC or a home equity loan, reaches that equity without refinancing. It is also simpler than a construction loan, which usually involves lender-controlled draws, inspections at each stage and a conversion at the end.

Pulling equity out of your home compares every route in one place.

What an ADU typically costs and how equity covers it

Costs vary widely, and anyone quoting you a single figure before seeing your lot is guessing. A garage conversion with existing utilities is at one end. A detached new-construction unit with its own foundation, utility connections, permits, impact fees and finishes is at the other, and the gap between them can be several times over. Prefab and modular units sit in between, with a fixed factory price plus site work that can surprise people.

What matters for financing is that you get real bids before you size the loan. A detailed bid from a contractor or a prefab vendor, plus a line item for permits and site work, gives you a number. If that number fits inside the equity calculator's estimate above, a second lien can fund the whole project. If the bid is larger than your available equity, homeowners typically close the gap with savings, reduce the scope, or build in phases. A cash-out refinance can sometimes reach further, but it replaces your first mortgage. Our comparison page covers that trade.

HELOC for a build that happens in stages

Most ADU builds are paid in stages. A deposit for design and permits, a draw when the foundation goes in, another at framing, another at rough mechanicals, and the balance at completion. A HELOC fits that rhythm exactly. You open a line up to an approved limit, draw each stage as it comes due, and pay interest only on what is out. The rate is variable, tied to the prime rate plus a margin, and many programs allow interest-only payments during the draw period.

The other reason a line fits an ADU is overruns. A line opened a bit above the bid gives you a cushion that is already approved, instead of a scramble halfway through the build. Read how a HELOC works for the full structure, including what happens when the draw period ends.

Home equity loan when you have a fixed contractor bid

If you have a signed contract for a set price, or you are buying a prefab unit with a known delivered cost, a home equity loan (often called a HELOAN) is the simpler tool. You receive the full amount at closing, the rate is fixed for the life of the loan, and the payment is the same every month. The trade-off is that you pay interest on the whole balance from day one, whether the contractor has been paid or not, and a true overrun would mean a second loan. See how a home equity loan works for the details.

Appraisal note: the loan is against today's value

This is the part that catches people. When a lender appraises your home for a HELOC or home equity loan, the appraiser values what exists today. The ADU you are about to build is not on the report, and the rent it will produce is not counted. The loan amount is based on your current value and your current income. If the finished unit raises your appraised value, that added equity can be borrowed against later, after a new appraisal confirms it.

Two practical points follow from this. Close the loan before any demolition or site work starts, because an appraiser looking at a torn-up yard will value it as torn up. And do not count on future rent to qualify. You qualify on the income you have now.

Is the unit for a parent or a disabled adult child instead of a tenant? If the goal is buying them a home rather than borrowing against yours, the Family Opportunity Mortgage program is built for that and allows owner-occupied terms.

The rent math

What we need

We will tell you exactly which documents apply once we talk. Generally the list looks like this.

• Your most recent first mortgage statement.
• Income documentation. Pay stubs and W-2s for employees. Self-employed homeowners can use our bank statement home equity loan, which qualifies on 12 months of business deposits instead of tax returns.
• A contractor bid, prefab quote or project budget, so the loan is sized to the build.
• Your homeowners insurance declarations page.

1. Run the number. Use the equity calculator to see roughly how much equity you could reach. No credit pull, no contact info.
2. Get bids. A real contractor or prefab number, plus permits and site work. Then call or text (916) 755-6080 and a loan officer will match the bid to a line or a loan.
3. Send documents and order the appraisal. We route the file to the program that fits, and the appraisal happens before any site work starts.
4. Close and build. Draw from the line as each stage comes due, or pay the contractor from the lump sum.

More questions? The full FAQ covers the rest. Already own a rental and want to tap its equity instead? That is a different product, our DSCR second mortgage.