What Is a Construction Loan for an ADU?

How draws work on an ADU

A home equity loan hands you money before the first shovel; a construction loan holds it back and pays it out against progress. The CFPB describes the money as “provided in a series of advances as the construction progresses” ².

In practice the lender agrees a draw schedule tied to milestones, such as foundation, framing, rough-in inspections, drywall and final, and releases each draw after someone confirms the stage is done.

Federal disclosure rules describe the same pattern from the lender’s side: the construction period “usually involves several disbursements of funds at times and in amounts that are unknown at the beginning,” with the borrower paying only accrued interest until construction is completed ³.

So the interest bill starts small and grows as the ADU does.

That staging is the main attraction for an ADU. Interest only runs on money already spent, and an inspection before each draw adds a check on your builder’s progress. The cost is paperwork: draw requests, lien releases from subcontractors, and waiting for inspections, which your contractor must plan cash flow around.

Three structures you will hear about

Renovation loans that can include an ADU

Fannie Mae HomeStyle Renovation. The Fannie Mae Selling Guide lets a borrower purchase a home or do a limited cash-out refinance with renovation costs included in the loan.

It sets no minimum renovation amount and no list of required improvements, requires the improvements to be permanently affixed, names accessory dwelling units as eligible, and says renovation work must be completed no later than 15 months after closing.

Freddie Mac CHOICERenovation. Freddie Mac says a CHOICERenovation mortgage is suited to converting an old barn, garage or shed into an ADU, that properties with ADUs can be financed through all its mortgage offerings, and that rental income from an ADU can count as qualifying income if its requirements are met.

Both are products you get through a participating lender, not from Fannie Mae or Freddie Mac directly. Ask the lender whether it offers them, how it appraises the as-completed value, and how renovation funds are released.

Sources: [4] [5]

Worked example: interest during the build

All inputs are hypothetical dollar amounts and a hypothetical rate, used only to show why staged draws change the interest bill. They are not typical ADU costs or current rates. Interest-only, simple monthly interest at a hypothetical 9% a year (0.75% a month).

Had the full 280,000 been borrowed as a lump sum in month 3, interest would have been 2,100 every month from the start.

Staging is the saving; the trade-off is the draw process. For real budget ranges, use the cost calculator rather than these placeholders, and see how long ADU construction takes to size the interest period.

Contract terms that change what the loan costs

• The draw schedule: how many draws, which milestones, and who inspects before each release.
• Retainage or holdbacks kept until final inspection or lien release.
• The interest-only period, and what happens if the build runs past it.
• Whether the loan converts automatically or you must requalify at completion.
• The value it is based on: current value, cost, or after-completion (as-completed) value.
• Fees per draw inspection, plus standard closing costs.

Strengths and limits for an ADU

What it means, in plain English

A construction loan pays for a building while it is being built. The bank does not hand you the money up front. It pays out in parts as the work gets done ².

Each payout is called a draw. Before each draw, someone checks that the stage is finished. You pay interest only on the money paid out so far.

When the ADU is done, the loan must be paid off, refinanced into a normal mortgage, or converted into one, depending on the type you chose.

Why it matters for an ADU

Many owners do not have enough equity today to pay for a full ADU. Some construction and renovation loans can look at the value of the finished project. That can open a larger budget than a home equity loan.

The draw checks also protect you. Money goes out only after work is confirmed, so it is harder to pay a builder far ahead of progress.

The cost is more paperwork, inspections and a higher rate than a normal mortgage ².

How an ADU construction loan works, step by step

1. Get plans and a detailed bid from your builder. Lenders usually want both.
2. Ask lenders which structures they offer: stand-alone, construction-to-permanent or renovation.
3. Apply. The lender reviews your income, credit, plans, bid and builder.
4. The lender sets the loan amount, sometimes using the as-completed value (the appraiser’s estimate of the value once built).
5. Close the loan and agree the draw schedule.
6. Your builder requests a draw at each milestone. An inspector checks, then money is released.
7. At completion, pay off, refinance or convert the loan to a permanent mortgage ³.

Worked example: a sample draw schedule

This draw schedule is hypothetical. The stages and percentages are made up to show how draws track progress. They are not typical ADU costs or a lender’s actual schedule. Total loan for the build: a hypothetical 250,000.

Shares add to 100%. If the lender holds back part of each draw until the end (retainage), your builder gets less at each step. Ask how the lender’s schedule lines up with your builder’s payment terms before signing either contract.

Where you will see these terms

• The loan commitment and Loan Estimate: amount, rate, interest-only period and fees ¹.
• The draw schedule attached to the loan: milestones and amounts.
• Your builder’s contract: its payment schedule should match the draws.
• Draw requests and inspection reports during the build.
• Lien releases (signed papers showing subcontractors were paid).
• The conversion or refinance papers at the end.

Rules: federal, California and other states

Federal disclosure rules cover construction loans. Regulation Z lets a lender disclose a construction-to-permanent loan as one transaction or as two ³.

Fannie Mae and Freddie Mac set program rules for renovation loans they buy, such as the HomeStyle 15-month completion rule ^{4 5}.

California has no ADU-only construction-loan rule, but your ADU needs a permit, and lenders may ask for it before funding. See ADU permits. Other states vary; see ADU laws by state. This is education, not financial advice.

Costs, and what drives them

Interest during the build depends on how much has been drawn and for how long. A slow build costs more interest.

Other costs can include closing costs, appraisal, and fees per draw inspection. Ask for a full fee list.

The build cost itself drives the loan size. For sourced ranges, see ADU cost statistics.

Common mistakes

Myth “The loan will cover any overrun.”

Reality The loan amount is fixed at closing. Overruns usually come from your own reserve.

Myth “My builder can start before closing.”

Reality Work done before closing may not be funded. Ask the lender first.

Myth “Construction loans are the same as mortgages.”

Reality They are short-term and generally cost more ².

Myth “Conversion is automatic.”

Reality Only in a construction-to-permanent loan. A stand-alone loan may need a new loan at the end ².

What to ask a construction lender

• Do you lend on ADUs, and on detached, attached or garage-conversion ADUs?
• Will you use the as-completed value?
• How many draws are allowed, and who inspects?
• What do you charge per draw?
• Do you hold back retainage?
• How long is the interest-only period, and what if the build runs late?
• Does the loan convert automatically, or must I requalify?
• What do you need from my builder (license, insurance, references)?

Checklist for your project

1. Get approved plans or a clear path to a permit.
2. Get a fixed-price or detailed bid. Compare bids with the bid comparison tool.
3. Check the builder’s license with the state.
4. Match the builder’s payment schedule to the lender’s draws.
5. Keep a cash reserve for overruns.
6. Plan the interest cost for a realistic build time.
7. Collect lien releases at every draw.

Key takeaways

• A construction loan pays out in draws as the ADU is built ².
• You pay interest only on what has been drawn ³.
• Rates are generally higher than a long-term mortgage ².
• Some renovation loans name ADUs as eligible ^{4 5}.
• Match the draw schedule to your builder’s contract before you sign.

Compare and plan

• Financing comparison toolStaged money versus available money
• ADU financing landscapeAppraisal and lender rules in depth
• ADU timeline plannerMap draws to construction stages
• ADU financing hub

Related terms

HELOC

A HELOC, or home equity line of credit, is an open-end line of credit secured by your home that lets you borrow repeatedly against your equity, up to a set limit, during a draw period, then repay what you borrowed over a repayment period.

Home Equity Loan

A home equity loan is a loan that uses the equity in your home as collateral and pays you the whole amount as one lump sum, usually at a fixed interest rate, which you repay in regular monthly payments from the start.

Cash-Out Refinance

A cash-out refinance is a new, larger mortgage that replaces your existing one and pays you the difference in cash, so the equity you have built becomes money you can spend, for example on an ADU.

ADU Grant

An ADU grant is money a public agency or program gives a homeowner toward the cost of building an accessory dwelling unit, which does not have to be repaid as long as the program’s conditions are met.

ADU Contractor

An ADU contractor is a licensed construction business that contracts to build an accessory dwelling unit, either doing the work itself or running the subcontractors who do the trades.

ADU Hard Costs

ADU hard costs are the money spent physically building an accessory dwelling unit: site preparation, foundation, framing, roofing, windows, mechanical, electrical and plumbing systems, finishes, and the trenching that brings utilities to the unit, together with the contractor’s labor, overhead and profit.

ADU Loan

Any loan used to build an ADU. Lenders rarely offer a product called an "ADU loan"; it is usually a home equity, construction, renovation or refinance loan.

ADU Financing

How homeowners pay for an ADU: cash, home equity loans and lines of credit, cash-out refinances, construction and renovation loans, and grants where they exist.

Also referenced from: ADU Contractor, Home Equity Loan, HELOC, Cash-Out Refinance, ADU Grant, ADU ROI