How a HELOC works for an ADU
A home equity line of credit (HELOC) lets you borrow against equity you've already built up in your primary home, up to a set credit limit. You draw funds as you need them — which can line up naturally with paying a contractor in phases — and typically pay variable interest only on what you've drawn. Because it's secured by equity you already have, a HELOC is often faster and simpler to set up than a construction loan, assuming you have enough equity to support the amount you need.
How a construction loan works for an ADU
A construction loan is built specifically around the building process: funds are typically released in stages as construction milestones are completed, rather than as a lump sum or flexible draw. Many construction loans convert into a permanent mortgage once the ADU is finished (a "construction-to-permanent" structure), rolling the short-term construction financing into long-term fixed financing. These loans often involve more documentation upfront — plans, a contractor agreement, a budget — since the lender is financing something that doesn't exist yet.
Side-by-side comparison
| Factor | HELOC | Construction Loan |
|---|---|---|
| What It's Secured By | Existing equity in your home | The completed project value (often converts to a mortgage) |
| How Funds Are Released | Draw as needed, up to your credit limit | Released in stages as construction milestones are completed |
| Typical Setup Time | Often faster, since it's based on existing equity | Often slower, since it requires plans, budget, and contractor documentation upfront |
| Interest Rate Type | Usually variable | Varies by lender and structure |
| Best Fit | Homeowners with substantial existing equity and a flexible timeline | Homeowners who want financing structured around the build itself, or with less available equity |
Rates, terms, and underwriting requirements vary by lender and change over time — these are general descriptions of how each product typically works, not a specific offer. See our ADU financing overview for the broader range of options, including cash-out refinancing.
Questions worth bringing to a lender
- How much equity do I actually have available, and does that cover the ADU project I'm planning?
- Can projected rental income from the ADU count toward my qualifying income for either loan type? See our guide to how lenders evaluate ADU rental income for how this generally works.
- What happens if construction costs come in higher than estimated — is there flexibility to draw more, and under what terms?
- For a construction loan, what documentation do you need before approval — plans, a signed contractor agreement, a detailed budget?
This isn't financial advice
United Build Partners isn't a lender, and this page describes how these loan types generally work, not a recommendation for your specific situation. A licensed lender can tell you what you actually qualify for and which structure fits your finances.
Frequently asked questions
Neither is universally better — it depends on how much equity you have and how you want funds released. A HELOC tends to suit homeowners with substantial existing equity who want flexibility; a construction loan tends to suit homeowners who want financing structured around build milestones or who have less available equity. A lender can assess which fits your specific finances.
Yes — a cash-out refinance is a third common option, replacing your existing mortgage with a new, larger one and taking the difference in cash. See our ADU financing overview for how it compares to a HELOC and construction loan.
Some loan programs allow a lender to count a portion of projected rental income toward your qualifying income, but this varies by lender and loan type. Ask directly what a specific program allows — see our ADU rental income guide for more on this.