Quick answer
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.
Unlike a home equity loan or HELOC, it does not add a second loan: the old mortgage is paid off and its rate disappears with it. That makes the new rate, applied to the whole balance, the number that decides whether it is worth it.
Quick facts
- What happens
- Old mortgage paid off; new, bigger mortgage takes its place 5
- Cash to you
- New loan amount − old balance − closing costs
- Number of loans after
- One first mortgage
- Key risk
- Giving up a lower existing rate on the full balance
- Renovation version
- Fannie Mae HomeStyle allows a limited cash-out refinance that funds renovation, including ADUs 6
How it works
The CFPB puts it in one line: you replace your existing mortgage with a bigger one and take the difference in cash 5. The lender orders an appraisal, sets the maximum new loan as a share of that value, pays off your old loan, takes its closing costs, and hands you the rest.
Because the whole debt moves to the new rate, a cash-out refinance can cost more than a smaller second loan even when its headline rate is lower than a HELOC’s. The CFPB notes that, depending on the terms, it may be more or less expensive than a HELOC 5, which usually carries a variable rate 4.
The only honest way to decide is to compare total monthly payments and total interest for your own numbers.
The diagram below puts the lender’s steps in order. Your cash comes out last, after the old loan and the closing costs are paid.
Worked example: the rate trade-off
Every number in this table is hypothetical, chosen to make the arithmetic visible. These are not current or typical rates, balances or prices. Payments are principal and interest on a 30-year fixed schedule, rounded.
| Keep mortgage + add second loan | Cash-out refinance | |
|---|---|---|
| Existing balance | 400,000 at a hypothetical 3.0% | Paid off |
| New money for the ADU | 150,000 second loan at a hypothetical 8.0%, 30 years | Included in the new loan |
| New first mortgage | — | 550,000 at a hypothetical 6.5%, 30 years |
| Monthly payment | ≈ 1,686 + 1,101 = 2,787 | ≈ 3,476 |
| Difference | — | ≈ 689 a month more, under these assumptions |
The refinance has the lower rate on the new money but re-prices the 400,000 that was cheap. Flip the inputs, an old rate higher than today’s, and the refinance can win. Run your own figures in the financing comparison tool, and include closing costs, which this example leaves out.
A decision rule
| If… | A cash-out refinance tends to… |
|---|---|
| Your current rate is above what you would be offered now | Make sense: you improve the rate on the whole balance and raise ADU money at once |
| Your current rate is well below today’s offers | Cost more than a home equity loan or HELOC that leaves the old loan alone |
| You need money in stages over a long build | Fit poorly: you pay interest on all the cash from closing day |
| You want to finance the ADU from its finished value | Look at a renovation version or a construction loan instead |
The renovation version: HomeStyle
Fannie Mae’s HomeStyle Renovation mortgage lets a borrower buy a home or do a limited cash-out refinance with the cost of renovations included in the loan amount.
Its Selling Guide says accessory dwelling units are eligible, and that renovation work must be completed within 15 months of closing.
In rare cases a lender can ask Fannie Mae for an extension to 18 months from closing 6. This is a product a participating lender offers, not something you apply to Fannie Mae for directly.
See the construction loan entry for how renovation and construction-to-permanent loans differ.
Sources: [6]
Strengths and limits
What it does well
- One loan and one payment instead of two.
- Can lower your rate if market rates have fallen since you borrowed.
- Usually a fixed-rate option is available on the new mortgage.
Where it falls short
- Resets the whole balance to today’s rate and often a new term.
- Closing costs apply to the full refinance, not just the new money.
- Lump sum, so interest runs on unspent ADU money.
- Your home secures a larger debt.
What it means, in plain English
Refinancing means swapping your current home loan for a new one. A cash-out refinance makes the new loan bigger than the old one. You keep the difference as cash.
You end up with one loan, not two. But that one loan has a new rate, a new term and new closing costs.
Your home is the security for the bigger loan. If you cannot pay, the lender can foreclose.
Safety and risk
A cash-out refinance moves all of your mortgage, not only the ADU money, onto the new rate and term. Your home secures the larger debt, so missed payments put the home itself at risk.
Why it matters when you build an ADU
An ADU often costs more than owners can pay in cash. A cash-out refinance can turn a large share of equity into money in one step.
The big question is your current rate. If it is low, a refinance moves your whole balance to today’s rate. That can raise your payment by more than the ADU money alone would.
If your current rate is higher than what you can get now, the math can work in your favor. The worked example above shows how both sides move.
How a cash-out refinance works, step by step
- Find your current balance and rate on your mortgage statement.
- Ask two or three lenders for a Loan Estimate for the new loan 1.
- Compare the new monthly payment with your current payment plus a second loan.
- Apply. The lender checks income, debts and credit.
- The lender values the home, often by appraisal, and sets the maximum loan using its loan-to-value limit 2.
- At closing, the new loan pays off the old one and the closing costs.
- You receive the rest as cash and start one new monthly payment.
Types of cash-out and renovation refinance
| Type | What it does | Fit for an ADU |
|---|---|---|
| Standard cash-out refinance | New, larger loan based on today’s value; cash paid at closing 5 | Works if your equity is large today |
| Limited cash-out renovation refinance (HomeStyle) | Includes renovation costs in the loan; work done within 15 months 6 | Can fit owners who need the finished value counted |
| Freddie Mac renovation options | Freddie Mac says its CHOICERenovation mortgage can fund converting a garage or shed into an ADU 3 | Ask a lender that offers it |
| Rate-and-term refinance (no cash out) | Changes the rate or term only | Does not fund an ADU by itself |
Worked example: how much cash you actually net
All numbers are hypothetical, used only for the arithmetic. They are not typical home values, limits or costs.
| Step | Hypothetical input | Result |
|---|---|---|
| Appraised value | 700,000 | — |
| Lender’s loan-to-value limit | 80% (each lender sets its own) | Largest new loan = 560,000 |
| Old loan payoff | 350,000 | 560,000 − 350,000 = 210,000 |
| Closing costs | 12,000 (hypothetical) | 210,000 − 12,000 = 198,000 |
| Cash you net for the ADU | — | About 198,000 |
Cash = (V × LTV) − B − C
V- Appraised value of the home, in dollars
LTV- The lender’s loan-to-value limit, as a decimal (each lender sets its own)
B- Payoff balance of your existing mortgage, in dollars
C- Closing costs paid from the loan, in dollars
Example with the hypothetical inputs above: (700,000 × 0.80) − 350,000 − 12,000 = 198,000.
The cash you net is smaller than the gap between the two loans. Check the closing costs on page 2 of your Loan Estimate 1, then compare the net figure with your full ADU budget.
Where you will see these terms
- Page 1 of the Loan Estimate: new loan amount, rate, whether it can change, and the monthly payment 1.
- Page 2 of the Loan Estimate: closing costs and the cash you will receive.
- The appraisal report: the value the loan is based on.
- The payoff statement from your old lender: the exact amount needed to close the old loan.
- The Closing Disclosure: the final numbers, which you should compare with the Loan Estimate.
Rules in California and other states
Mortgage disclosure rules are federal, so the Loan Estimate looks the same in every state 1. Fannie Mae and Freddie Mac set their own program rules for the loans they buy 6 3.
California has no cash-out rule written just for ADUs. Its ADU law affects your budget in other ways, such as fees. Other states vary; see ADU laws by state.
This page is education, not financial or legal advice. The lender decides what you qualify for.
Costs, and what drives them
You pay closing costs on the whole new loan, not just the cash part. These can include appraisal, title and origination charges 1.
The other big cost is the new rate on the full balance. Then the term: starting a new 30-year loan can lower the payment but add years of interest.
Build cost drives how much cash you need. Use the ADU cost calculator for a range before you size the loan.
Common mistakes
- Myth “A lower rate than my HELOC offer means it is cheaper.”
- Reality The refinance rate applies to the whole balance. Compare total payments, not rates 5.
- Myth “The cash is the difference between the two loans.”
- Reality Closing costs come out first.
- Myth “A refinance counts the ADU’s future value.”
- Reality A standard one uses today’s value. Renovation products work differently 6.
- Myth “Restarting at 30 years is free.”
- Reality A lower payment over more years can mean more total interest.
What to ask a lender
- What is the most I can borrow, and what loan-to-value limit did you use?
- What are the total closing costs, and how much cash will I net?
- What will my new monthly payment be, including taxes and insurance?
- How does that compare with keeping my loan and adding a second one?
- Do you offer HomeStyle or CHOICERenovation, and how do you release renovation funds?
- Is there a prepayment penalty?
Checklist before you refinance for an ADU
- Write down your current rate, balance and years left.
- Get a full ADU budget with a reserve.
- Get Loan Estimates for a cash-out refinance and for a second loan.
- Compare total monthly payments and total interest over the time you plan to stay.
- Check the rent the ADU may bring with the rent estimator.
- Close before you sign the build contract.
Key takeaways
- A cash-out refinance replaces your mortgage with a bigger one and pays you the difference 5.
- Your whole balance moves to the new rate.
- It tends to suit owners whose current rate is higher than today’s offers.
- Closing costs apply to the full loan.
- Renovation versions can fund an ADU under program rules 6.
Related guides
- ADU financing landscapeAppraisal rules that decide what an ADU is worth to a lender
- ADU financing statistics
- ADU financing hub
- ADU ROI calculatorCheck the rent covers the new payment
Questions about cash-out refinance
Can I do a cash-out refinance to build an ADU?
Yes, if your equity supports a large enough new loan. The cash can pay for design, permits and construction. Compare the new payment on the whole balance with keeping your mortgage and adding a second loan.
Is a cash-out refinance better than a HELOC for an ADU?
It depends on the terms. The CFPB says it may be more or less expensive than a HELOC. It tends to lose when your current rate is much lower than today’s, and to win when it is higher.
How long does a cash-out refinance take?
It goes through a full mortgage underwriting and appraisal, so it takes longer than an unsecured loan; your lender gives the timeline. Plan it before you sign a construction contract.
Can a refinance be based on the value after the ADU is built?
A standard cash-out refinance uses today’s appraised value. Renovation products such as Fannie Mae HomeStyle can include renovation costs in the loan; ask a lender how it appraises the finished project.
What is the downside of a cash-out refinance?
You give up your current rate on the whole balance, pay closing costs on the full new loan, and owe more against your home. If your old rate was low, your payment can rise by more than the cash alone would suggest.
How much cash can I take out in a refinance?
It depends on your home’s value, your current balance and the lender’s loan-to-value limit, minus closing costs. Each lender and program sets its own limit. The net-cash example above shows the steps with hypothetical numbers.
Does a cash-out refinance need an appraisal?
Lenders need a value for your home to set the loan amount, and often order an appraisal. Ask the lender how it values the home and who pays.
Is a cash-out refinance better than a home equity loan for an ADU?
Neither always wins. A home equity loan keeps your first mortgage and its rate. A refinance replaces it. Compare total monthly payments and total interest using real Loan Estimates for both.
Can I use Freddie Mac or Fannie Mae renovation loans for an ADU?
Fannie Mae’s HomeStyle names ADUs as eligible, and Freddie Mac says its CHOICERenovation mortgage suits converting a garage or shed into an ADU. You apply through a participating lender, not the agencies.
Sources
- Consumer Financial Protection Bureau, Loan Estimate explainer, retrieved .
- Consumer Financial Protection Bureau, What is a loan-to-value ratio?, retrieved .
- Freddie Mac Single-Family, Accessory Dwelling Units, retrieved .
- Consumer Financial Protection Bureau, What is a home equity line of credit (HELOC)?, retrieved .
- Consumer Financial Protection Bureau, What other types of loans are similar to a HELOC?, retrieved .
- Fannie Mae Selling Guide, B5-3.2-01 HomeStyle Renovation Mortgages, retrieved .
Expert review
Written by the HyreADU Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Definition from the CFPB; HomeStyle terms from the Fannie Mae Selling Guide, read 7 October 2026. Example payments computed with the standard amortization formula from labelled hypothetical inputs; no market rates quoted. Education, not financial advice.
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