How to Finance an ADU (accessory dwelling unit) in the Pacific Northwest (2026)

An ADU financing plan needs to cover the complete project and make funds available when payments are due. Your equity, income, existing mortgage, property, and intended use all affect the options a lender can offer.

Start with a property review and a lender conversation before committing to construction. Wolf can provide a proposal and payment schedule; the lender determines loan eligibility, appraisal requirements, and how money will be released.

Set the project budget first

The table above shows Wolf’s published planning prices. A model price is the home itself. The project budget also needs appliances, permitting service, agency fees, delivery, installation, and any additional site work. The written proposal should identify inclusions and exclusions so that an item already included in a project total is not added again.

Installation is quoted after reviewing the property. Foundation, access, utility connections, delivery, septic or well work, ramps, and decks are confirmed in your written proposal.

Review the home and project cost guide for starting prices, delivery and setup, and the work your property may need. The written proposal confirms your project price. Ask the lender how to budget for contingencies, closing costs, and payments during construction.

Compare the financing paths

Cash and home equity

Cash avoids loan interest and lender draw requirements, but using savings reduces the cash you retain for other needs. Compare that tradeoff with the full cost and repayment obligations of borrowing.

A HELOC is a revolving line secured by your home. It can provide funds in stages, but rates are usually variable, fees and draw restrictions differ, and payments can increase when repayment begins. A lender can also reduce or freeze available credit under certain conditions. A home-equity loan instead provides a lump sum under its agreed repayment terms. Both require enough eligible equity and lender approval; a loan secured by your home puts the home at risk if payments are not made.

Cash-out refinance

A cash-out refinance replaces the existing mortgage with a larger loan and releases eligible cash after the old balance and closing costs are paid. Compare the new rate and term on the whole mortgage, along with fees, monthly payments, and total borrowing costs over the time you expect to keep the loan. A low monthly payment alone does not establish which option costs less.

Renovation loans

These programs can finance eligible improvements through a mortgage. New construction, conversions, attached units, and detached ADUs do not necessarily qualify under the same rules.

• Fannie Mae HomeStyle Renovation: current guidance permits a lender to fund up to 50% of planned renovation costs at closing for eligible expenses, including certain fees and deposits. Later draws require periodic inspections. This is an allowed structure, not a promise that a particular lender will fund a factory deposit.
• Freddie Mac CHOICERenovation: Freddie Mac identifies this as an option for constructing a new ADU or renovating an existing one. Ask the lender to confirm the proposed property, construction scope, appraisal, and payment schedule qualify.
• FHA 203(k): HUD’s Limited program covers eligible minor, non-structural work up to $75,000. Standard 203(k) supports major rehabilitation and structural work, with a consultant and additional requirements. Have the lender confirm the specific ADU project is eligible before relying on either program.

Construction-to-permanent financing

Construction financing pays for approved work through a lender’s draw process. Permanent financing then pays off or replaces the construction balance. Products can involve a single closing or separate closings; ask about fees, interest during construction, inspections, completion deadlines, and requirements for conversion to the permanent mortgage.

Confirm factory payments before paying a deposit

A modular home’s production payments can come due before delivery to the property. Give the lender the actual contract and ask: Can this loan fund the factory deposit and completion payment when they are due, and what evidence will you require?

Wolf’s published schedule is 25% at the start of production and 75% at production completion, with a separate 50/50 schedule for delivery and setup. Your signed agreement controls the amounts, milestones, and scope. Obtain the lender’s acceptance of that schedule before assuming it can cover those payments. Ask whether you must provide any interim funds yourself.

Keep rental permission separate from loan qualification

Permission to rent an ADU does not mean projected rent can be used to qualify for a mortgage. For example, Fannie Mae’s current guidance permits income from one existing ADU for specified purchase or limited cash-out refinance transactions, with ADU income capped at 30% of total qualifying income. Other programs have their own documentation and limits.

Washington’s RCW 36.70A.680 and .681 establish ADU protections for covered urban areas, subject to their applicability and exceptions. These include limits on owner-occupancy requirements and a cap on ADU impact fees of 50% of those for the principal unit. They do not establish blanket statewide rental permission for every rural property or cap every utility charge. Check the Washington rules guide and the rules for your parcel and intended rental use.

Bring the lender a defined scope

Wolf can supply the selected model, property-specific proposal, payment milestones, and project documents your lender requests. Published model pricing helps establish the home portion of the budget; it does not establish a fixed price for unreviewed site work or guarantee underwriting approval.

Request a free property evaluation to identify the next planning steps, or see our financing page for payment details and lender contacts. Wolf is the builder, not the lender. This is general information; compare current written offers and confirm your project’s requirements with the lender and permitting agencies.