Banks That Offer a HELOC for an Accessory Dwelling Unit

The Quick Read: A HELOC can fund an accessory dwelling unit, but the line is sized on what the property is worth today, not on what the finished unit will be worth or rent for, and which bank or credit union will write it depends on occupancy, credit, vesting, and how the lender treats construction and rental use. Lendmire is a mortgage broker, not a lender. It shops a network of wholesale HELOC lenders and matches the file to the program, so this article explains what those lenders look for instead of ranking any bank.

• The line sizes off current value, so an unbuilt unit adds nothing to it.
• On an investment property, the network ceiling is 70% combined loan-to-value (CLTV), with a 700 minimum credit score and a $500,000 maximum line.
• On a primary residence, the ceiling reaches 90% CLTV, and only at a 720 or better credit profile.
• At least 75% of the line is drawn at closing, so it is not a phased construction facility.
• A property titled in an LLC cannot take these lines, which is the sharpest difference from a DSCR loan.

Can a HELOC Really Pay for an ADU?

Yes. A home equity line of credit (HELOC) is a revolving line you borrow against the equity in a property you already own. Equity is the property’s value minus what you owe on it. There is no special ADU HELOC category. The line is an ordinary HELOC, and the accessory dwelling unit is simply what you spend the money on.

The usual alternatives are narrower. Shelterforce reports that renovation loans are so restrictive that HELOCs are the more common way homeowners pay for ADU construction. The same article notes that mainstream mortgage channels have not let lenders count projected rental income toward an ADU property’s value. That limits how much a homeowner can borrow. The article dates from 2022, so treat it as background rather than a current rulebook.

Researchers have long flagged the same squeeze. The Berkeley Terner Center documents high upfront costs and trouble accessing financing as barriers to building ADUs. A line that rides on existing equity gets around the upfront-cost problem, but it brings its own limits.

Which Banks Offer This? It Depends on the Lender Type

No single list of banks answers this question, because the answer changes with the property and the borrower. Three kinds of lenders write home equity lines: depository banks, credit unions, and non-bank lenders. Each sets its own rules on occupancy, property type, construction use, and rental use.

Large retail lenders tend to build their lines around owner-occupied homes. Many lenders do not offer lines on investment properties at all, as NerdWallet notes. A small number of lenders market lines built for ADUs, and a few of those consider projected rent. That is the exception, not the rule.

This is where a broker earns its keep. Lendmire works with a network of wholesale HELOC lenders and matches the scenario to the program. The best program for your situation depends on the property type, your credit profile, the leverage you need, and how you hold title. HELOC placements run in 16 full-service states, which is narrower than Lendmire’s 41-market DSCR footprint.

If you shop on your own, ask each lender these questions before you apply:

• Does the line allow the property’s current occupancy (primary, second home, or investment)?
• Will the lender permit the funds to be used for construction?
• Does the loan agreement prohibit renting the property or the new unit?
• Will the lender consider the future unit in the valuation, or only current value?
• Can the property be titled in an LLC?
• What happens to the line if the property’s value drops mid-build?

How the Line Is Sized

Lenders size the line from the property’s current appraised or estimated value. The CFPB’s HELOC booklet explains the method with a 75 percent example. The lender takes a percentage of the home’s value and subtracts what you owe. The result is the most you can borrow.

Because the math uses today’s value, an unbuilt ADU adds nothing. The gap between your equity and your build cost is the problem you plan around.

Here is the percentage math with modeled inputs. Say a primary residence carries a first mortgage equal to 55% of its value. A borrower at a 700 score can reach 85% CLTV on a primary residence, up to $500,000. The line can reach about 30% of current value. Now say an investment property carries the same first mortgage. The investment ceiling is 70% CLTV, so the room is about 15% of value. Same debt, half the room. A line is also capped by its maximum dollar size, whichever limit binds first.

Lenders may also reduce or freeze a line if the property’s value drops. Plan the budget so a mid-build freeze would not strand the project.

What the Network’s HELOC Programs Allow

The network runs two wholesale HELOC programs. Both are standalone lines that can sit in first or second lien position. A second lien means a loan paid in addition to the first mortgage. The programs differ mainly in how long you can draw. The 3-year-draw program pairs a 3-year interest-only draw period with a 17-year repayment period. The 5-year-draw program pairs a 5-year draw with a 25-year repayment. Investment lines run the 5-year-draw structure only.

Leverage depends on occupancy, so one number never fits every file. Each figure below is subject to lender guidelines and full file review.

Credit tiers step the ceiling down. A primary residence at a 640 score tops out at 80% CLTV up to $500,000, and at 620 it drops to 70% up to $400,000. A second home at 640 tops out at 75% CLTV. An investment property at 700 or above carries 70% CLTV with no higher tier.

Those are market figures. On this network, the investment-property minimum is 700, and the 70% CLTV ceiling applies.

A line above $500,000 is available on primary residences only. It needs a score of 700 or better (720 on the 5-year-draw program), caps at 75% CLTV, and requires a full appraisal.

Other program rules matter for an ADU file:

• Debt-to-income (DTI): the maximum is 50%, and 45% for credit profiles from 600 to 679. Qualifying uses the interest-only payment on the maximum draw.
• Valuation: lines at or below $500,000 ordinarily run an automated valuation instead of a traditional appraisal. A higher CLTV may require a second valuation, and you can request a full appraisal.
• Exposure: a borrower can hold up to three lines. An investor with more than 15 financed properties is not eligible.
• Credit report: it must be no more than 90 days old at closing.

Draws, Repayment, and the 75% Catch

The 75% catch is the detail that surprises builders most. On both programs, at least 75% of the line is drawn at closing. The money does not trickle out as your contractor invoices. You carry most of the balance from day one.

The CFPB describes a HELOC as a line you can borrow against repeatedly during a draw period. A repayment period follows, when you can no longer borrow. Lenders often schedule full repayment over 10 or 20 years. The CFPB also warns that you could lose your home if you cannot repay.

Two more mechanics apply here. Pricing floats during both the draw and the repayment period, and it never converts to a fixed structure. The 5-year-draw program sets a $1,000 minimum for later draws after closing.

This is why a HELOC is not a construction loan. It gives you a revolving line against current equity. It has no inspection-based draw schedule and no completion test. If your build runs long, the interest-only draw clock keeps running.

Where the General Rule Breaks

Rental use. Some lines prohibit renting the property under the line’s own terms. An ADU that you plan to lease can run into that clause. Read the agreement before you draw.

ADU rent. A HELOC lender generally does not count projected rent from the unit. The exceptions are lenders that explicitly consider it. Count on sizing from current value alone.

LLC title. These lines require title held by the individual borrower or a revocable living trust. LLCs, corporations, partnerships, and irrevocable, blind, or land trusts cannot hold title. If the property already sits in an LLC, you need a vesting change or a different loan. DSCR loans to an LLC are available subject to program terms, which is why that route exists.

Classification. A legal, separately rentable ADU can change how a property is classified, for example from single-family to 2-4 units. That can change credit minimums. On the 5-year-draw program, a 2-4 unit property needs a 640 score or better.

Vacant land. An ADU is accessory to a main dwelling. A lot with no main home may not support one, and the line needs eligible collateral.

Prefabricated units. Modular factory-built homes are eligible on the 5-year-draw program only. Manufactured homes, co-ops, condotels, log homes, commercial, mixed-use, and agricultural-zoned properties are not eligible on either program.

Credit history. A bankruptcy needs 4 years of seasoning from discharge or dismissal on both programs. Foreclosure history splits. One program seasons a foreclosure in 7 years and a deed-in-lieu, pre-foreclosure, or short sale in 4. The other declines the history entirely.

HELOC First, DSCR Cash-Out Second

The investor decision is usually about the exit. A line carries variable pricing and a repayment period that can start before the ADU leases up. Many investors plan to refinance into longer-term debt once the unit is legal and rented.

A DSCR cash-out refinance is one route. A debt service coverage ratio compares monthly rent to the full monthly payment on principal, interest, taxes, insurance, and any association dues. The loan is reviewed primarily on property-level rental income covering the payment, subject to lender guidelines. Cash-out refinances top out around 75% LTV across most of the network, and about 6 months of seasoning is the common expectation. Most programs want a score near 660, and 700 or better unlocks the strongest leverage tiers. Reserves commonly run around 6 months of the full payment but vary by lender, leverage, and loan size.

Coverage of 1.00 is where many select programs start. A separate select-lender path takes coverage below 1.00, with leverage and terms adjusted. Clearing 1.00 does not mean positive cash flow, because repairs, vacancy, management, utilities, and capital costs sit outside the calculation. The complete DSCR loans guide walks through how the ratio works.

Your HELOC can also get in the way of that refinance. A second lien raises your combined leverage. A separate walkthrough covers using an investment property HELOC for an accessory dwelling unit from the investor’s side. Work out the combined leverage you will carry before the first draw. Then check it against the refinance ceiling.

Key Terms Defined

Accessory dwelling unit (ADU): a second, smaller living unit on the same lot as a main home, such as a backyard cottage or a garage conversion.

Combined loan-to-value (CLTV): all loans secured by the property, added together, divided by its current value.

Draw period: the stretch when you can borrow from the line, usually with interest-only payments.

Repayment period: the stretch after the draw period when you repay principal and interest and can no longer borrow.

Second lien: a loan that sits behind your first mortgage and is paid in addition to it.

Vesting: the legal way title to the property is held, such as individual name, revocable trust, or LLC.

What the Decision Looks Like in Practice

Start with occupancy, because it sets the ceiling. Then size the line from current value and subtract your first mortgage. Compare that room to the build budget. If the gap is wide, a HELOC alone will not do the job, and the DSCR cash-out route may fit better.

Gather these items before you apply:

• Current mortgage statement and property details.
• Proof of how title is held.
• A credit profile you have reviewed, since the report must be recent at closing.
• Your build budget and a plan for the interest-only carry.
• A clear view of whether you will rent the unit and whether the loan terms allow it.

Short-term rental rules can vary by city, county, HOA, and property type, so investors should confirm local rules before relying on projected rental income.

Next Step

If you are considering a home equity line and want to see how the numbers work, Lendmire can help you compare HELOC options based on the property, the equity available, credit profile, combined leverage, and your goals. Lendmire arranges financing through select lenders in its wholesale network and is not a lender. Every file is underwritten individually, and nothing here is a commitment to lend.

About Lendmire

As a mortgage broker (NMLS# 2371349), Lendmire helps homeowners and real estate investors in its 16 full-service states open home equity lines of credit arranged through wholesale lenders. Lendmire is never the lender; line amounts, ceilings and terms are set by the lender under its guidelines. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. Shelterforce – How Financing Barriers Keep ADUs Expensive

2. Berkeley Terner Center

3. NerdWallet – HELOC on an investment property

4. CFPB – HELOC booklet

5. CFPB: What Is a Home Equity Line of Credit HELOC