Phoenix homeowners are sitting on serious equity right now. Even with the market cooling from its 2022 peak, the median home value in Metro Phoenix is still hovering around $420,000 as of recent market data — and a lot of people who bought five or more years ago are carrying $100,000 to $200,000+ in usable equity. That’s not theoretical wealth. That’s a resource you can actually deploy.
More and more of my clients are using that equity to build in-law suites or accessory dwelling units (ADUs). The motivations vary — aging parents moving closer, adult kids who can’t crack the Phoenix rental market, or simply generating $1,200–$1,800 per month in rental income from the backyard casita. Whatever the reason, the question always lands the same way: How do I pay for it?
Three options come up most often — a HELOC, a cash-out refinance, or a construction loan. They’re not interchangeable. Picking the wrong one can cost you tens of thousands of dollars over time or leave you scrambling mid-build when funds dry up.
The HELOC: Best for Flexibility, Worst for Rate Predictability
A home equity line of credit works like a credit card backed by your home. You get approved for a limit — say, $80,000 — and draw from it as needed. You only pay interest on what you’ve actually pulled out.
For an ADU or in-law suite project, this is attractive because construction costs rarely come in perfectly timed. You pay the framing crew this month, the electrician next month, the finish crew two months after that. A HELOC lets you match your borrowing to your actual spend.
The catch? HELOCs are almost always variable-rate products. Most are tied to the prime rate, which has been elevated. If rates drift up while you’re mid-build, your cost of borrowing rises with them. That’s real exposure.
Here’s a quick comparison to orient you:
| Feature | HELOC | Cash-Out Refi | Construction Loan |
|---|---|---|---|
| Rate type | Variable | Fixed | Fixed or variable |
| Draw flexibility | Yes — draw as needed | No — lump sum at close | Yes — disbursed in stages |
| Existing mortgage affected | No | Yes — replaces it | No |
| Best for | Phased builds, smaller projects | Replacing a high-rate mortgage anyway | Large standalone ADU builds |
| Typical closing costs | Low | 2–3% of loan amount | Higher; includes inspection fees |
If you want to go deeper on comparing HELOC options, Best HELOC Lenders in 2026 is worth a read before you shop lenders.
Cash-Out Refinance: The Right Call in One Specific Scenario
A cash-out refi replaces your entire existing mortgage with a new, larger one. The difference between what you owe and what you’re borrowing comes to you as cash at closing.
On paper, this sounds clean. One loan, fixed rate, done. But here’s the problem most of my clients run into in 2025 and 2026: they bought or refinanced when rates were at 3–4%. Doing a cash-out refi today means trading that low rate for a mortgage in the 6.5–7% range on your entire loan balance. That monthly payment jump often wipes out any rental income the ADU was supposed to generate.
The cash-out refi makes sense when you bought recently at a higher rate and your equity has grown enough to pull from. Or when you have a genuinely small remaining balance and the blended cost of the new loan still pencils out. Run the math explicitly before you pull the trigger.
One more thing: lenders typically cap cash-out refis at 80% loan-to-value, and they’ll order a full appraisal. If your home’s value has softened in your specific neighborhood — some parts of the East Valley and Surprise saw modest corrections in late 2023 and 2024 — that appraisal could limit how much you actually net.
Construction Loans: Right for Bigger Projects, Messier to Execute
If you’re building a freestanding ADU — a detached casita with its own entrance, kitchen, and bathroom — rather than converting existing space, a construction loan might be the most appropriate product.
Construction loans work in draws. The lender releases money in stages as specific milestones are hit: foundation poured, framing complete, rough-in finished, and so on. An inspector signs off at each stage. It keeps everyone accountable and ensures you’re not handing a contractor a lump sum upfront.
The tradeoff is complexity. You’ll need approved plans, a licensed contractor with a track record, and more documentation than a typical mortgage. Some lenders offer construction-to-permanent loans that roll into a standard mortgage once the build is done — that saves you from paying closing costs twice.
In Maricopa County, ADU permitting has gotten easier following Arizona’s statewide ADU preemption rules, but you still need to clear setbacks, utility connections, and sometimes HOA approval. That process adds time — typically three to six months before a shovel hits the ground.
What Arizona Homeowners Often Miss
A few things that come up in my conversations with clients that don’t always make it into generic financing articles:
- Rental income from the ADU usually can’t be used to qualify for the loan — at least not until you have a signed lease and often a history of rental receipts. Plan your debt-to-income ratio without it.
- Detached ADUs can add 20–35% to your property’s assessed value, which means higher property taxes. Budget for it.
- Gilbert and Chandler have some of the most streamlined ADU permitting in the Phoenix metro right now. If you’re near those cities, your timeline could be shorter than you expect.
- HOA restrictions still apply in many communities regardless of state law. Check your CC&Rs before you spend a dime on plans.
Making the Call: A Simple Decision Framework
The right financing option usually comes down to three factors:
- Your current mortgage rate. If it’s below 5.5%, protect it. Use a HELOC or construction loan, not a cash-out refi.
- Your project size. Under $60,000? A HELOC is often the cleanest path. Over $100,000 for a full detached build? A construction loan deserves serious consideration.
- Your risk tolerance on rates. If variable-rate exposure keeps you up at night, structure your deal to get fixed-rate debt even if it costs a little more upfront.
It’s also worth thinking about the bigger picture here. Arizona’s housing crunch is real. An ADU adds supply to a market that desperately needs it, and the rental income can meaningfully offset your carrying costs. If you’re weighing the ADU’s financial case more broadly, how to get equity out of your home without refinancing covers additional equity strategies worth stacking alongside these.
The Phoenix metro has added more multigenerational and ADU-oriented construction in the past three years than at any point in the last decade. Financing is available. The terms are workable if you choose the right product for your situation.
Get a lender conversation going before you finalize your plans — not after. What you qualify for shapes what you build, and knowing that early saves months of redesign headaches down the road.