HELOCs and home equity
Can I use a HELOC to build an ADU?
Written for Shawn Way MortgageUpdated Sources checked
The short answer
Existing home equity may help finance an accessory dwelling unit, such as a backyard home or garage conversion. A second-lien HELOC or home equity loan can leave your first mortgage in place. Check whether the available borrowing covers the full project, then compare renovation or construction financing if it does not. The property and lender must qualify.
What should the ADU budget include?
Start with design and planning, local permit requirements, site work and utilities, construction, contingency and any carrying costs before completion. Ask for a staged payment schedule. An early concept estimate is a starting point to refine with local professionals.
Can I borrow based on the finished ADU’s value?
Do not assume a standard equity line includes the value of an unbuilt unit. Ask which appraisal and valuation rules apply. Certain renovation or construction products can address a completed project, with separate eligibility and construction requirements.
Fannie Mae describes renovation and construction-to-permanent paths for qualifying ADU projects. That does not mean every lender offers each path or every property qualifies.
Will future rent cover the loan payment?
Build a payment plan that works during design and construction, before rent exists. Then account for vacancy, repairs, insurance and operating costs. Whether a lender can count ADU rent for qualification depends on the program and documentation. Projected rent is not guaranteed income.
What should I bring to the first financing conversation?
- Property location, current home value and existing loan balances.
- The proposed unit type, plans and permit stage.
- Contractor estimates, payment timing and a contingency budget.
- Whether the unit is for family use, rental use or another purpose.
Confirm local approvals with the relevant authority. Loan approval does not grant permission to build.
Questions people ask
Is an ADU loan always a separate special product?
No. Existing equity financing, a renovation mortgage or construction financing may be considered. The right comparison depends on the property, project and borrower.
Will a HELOC pay for every ADU project?
No. The available line depends on equity and lender limits as well as qualification. Compare the amount available with the complete project budget before committing.
Sources
- Fannie Mae: Accessory dwelling units and financing options
- CFPB: Comparing a home equity loan and a HELOC
Checked November 1, 2026. Rules, limits and program terms change; confirm current details before you rely on them. Educational information, not a commitment to lend or a determination of eligibility.