Top Investment Property HELOC Providers to Build a Granny Flat or ADU

The Quick Read: An investment-property HELOC can fund a granny flat or ADU build, but the best provider depends on your situation: the line is sized on today’s value rather than the finished unit, the property must sit in your own name or a revocable trust, and few lenders write these lines at all. Treat any ranked list of names with caution. What matters is how the lenders that write these lines underwrite the file.

• On an investment property, the network ceiling is 70% combined LTV, with a 700 minimum credit score and a maximum line of $500,000, subject to lender guidelines.
• Sizing uses the property’s current value. An ADU that does not exist yet adds no borrowing room.
• At least 75% of the line is drawn at closing. The draw period is 5 years interest-only, followed by 25 years of repayment, and pricing floats.
• An LLC cannot hold title on these lines. A rental already deeded to an LLC points toward a DSCR cash-out refinance instead.
• Many investors treat the line as a build-phase tool and plan a DSCR cash-out refinance once the unit is leased.

Who Are the Top Investment Property HELOC Providers for an ADU Build?

No single provider tops the list for every investor. The lenders that write investment-property lines are a small group, and each sets its own limits on credit, leverage, title and property type. The right fit for your file depends on your credit profile, the equity you hold, how the property is titled, and how much you need to borrow.

Lendmire is a mortgage broker, not a lender. It works with a nationwide network of wholesale HELOC lenders and matches a scenario to the program that fits. Here is how the provider types differ in general terms.

NerdWallet notes that rental-property HELOCs mean a smaller pool of lenders and stricter qualification than a line on a primary home. A broker’s advantage is breadth: one application can be matched against several sets of guidelines.

What Is an Investment-Property HELOC?

An investment-property HELOC is a revolving credit line secured by equity in a rental. You draw what you need during an interest-only draw period, then the balance amortizes. It can sit in first or second lien position, so the lender looks at combined LTV, which is all liens on the property divided by its value.

On Lendmire’s network, investment lines run $25,000 to $500,000. The 70% combined LTV ceiling applies on an investment property at both the 700 and 720 credit tiers. A score above 700 buys eligibility rather than extra leverage. Larger lines exist only on primary residences, so they never apply to a rental.

Market surveys report that investment-property lines at some lenders require six months or more of cash reserves and debt-to-income between 40% and 50%, per NerdWallet. On Lendmire’s network, DTI maxes at 50%, qualified on the interest-only payment calculated at the maximum draw. Reserve expectations differ by lender, so confirm them during file review.

How Does Underwriting Treat an ADU Build, Step by Step?

Underwriting looks at the rental as it stands today. It does not look at the property you plan to have. The sequence runs like this.

1. Title check. The property must be held by you personally or by your revocable living trust. Fee simple and leasehold both work. LLCs, corporations, partnerships and irrevocable, blind or land trusts cannot hold title.

2. Eligibility check. Single-family, 2-4 unit, PUD, townhome and condo (including non-warrantable) properties are eligible. Manufactured homes, co-ops, condotels, log homes, commercial, mixed-use and agricultural-zoned properties are not.

3. Credit check. A 700 score is the hard floor on an investment line. The lender pulls a single-bureau score tied to the primary wage earner, and the report can be no more than 90 days old at closing.

4. Valuation. Lines at or below $500,000 ordinarily use an automated valuation with no traditional appraisal. A higher combined LTV may trigger a second valuation, and you can request a full appraisal anyway.

5. Sizing. The lender takes value times 70%, then subtracts existing liens. What remains is the most the line can be, up to the line cap.

6. DTI check. Your debts are measured against income, using the interest-only payment on the full line.

Here is the sizing step as a picture, using percentages only. Say the rental’s current value is 100 units. At 70% combined LTV, total liens cannot exceed 70. If your first mortgage already sits near 45, the new line has room for roughly 25 units of value. That number must cover the ADU budget. A plan to build an ADU whose cost exceeds that remaining room fails at this step, no matter what the finished unit would be worth.

Construction lenders reverse this logic. Their loans are short-term and based on the projected value after construction. A HELOC does not do that.

Which Collateral Should Carry the Line: The Rental or Your Home?

Some investors secure the line with their own residence and spend the money on the rental. That is a different product with different risks. A residence line can reach higher leverage tiers, but it puts your home behind a rental project.

The rental line keeps the risk on the rental but limits leverage and size. The home line offers more room, but a weak ADU result then threatens where you live. Choose the rental as collateral if you want the downside contained to the project’s property, and the home only if you need the extra capacity and can accept that exposure.

How Do the Draw and Repayment Terms Fit a Construction Schedule?

Investment lines run one structure: a 5-year interest-only draw, then 25 years of fully amortizing repayment. Pricing floats through both periods and never converts to fixed.

At least 75% of the line is drawn at closing. This matters for builders. A phased-draw plan, where you pull money as each construction stage completes, does not fit well. You will carry interest on most of the line from the start, while the ADU earns nothing. Later draws after closing carry a $1,000 minimum, and the lender reviews your file on the payment at the maximum draw.

Stress-test the carry before you apply. Add the interest-only cost of the line to the existing first mortgage, taxes and insurance, and ask whether the rental covers that for the full build. Many builds run longer than planned. A plan that works only if the unit leases on schedule is thin.

Where Does the General Rule Break?

Rent from a unit that doesn’t exist. A HELOC underwrites on your credit, income and debts. Planned ADU rent is not a lease, and it does not boost the file. Agency guidance on ADU income, such as Fannie Mae’s ADU income sheet, covers existing units on one-unit principal residences and calls for a market rent schedule (Form 1007). That is a contrast case, not a rule for investment lines.

An LLC-held rental. The title rule is the sharpest difference from a DSCR loan. Either you change vesting before applying, or you skip the line and use a DSCR cash-out refinance, which can lend to an LLC depending on program guidelines.

A large portfolio. A borrower is limited to three lines and is ineligible with more than 15 financed properties. Owners of larger portfolios often meet the cap before they hit the credit tests.

Credit history. Bankruptcy needs 4 years of seasoning from discharge or dismissal. Investment files follow a 7-year path after foreclosure and a 4-year path after a deed-in-lieu, pre-foreclosure or short sale.

Unpermitted or ineligible builds. A unit built without permits may add little or nothing to appraised value. A manufactured-home ADU is ineligible. Neither a line nor a DSCR loan through the network covers manufactured homes (single- or double-wide), log homes or barndominiums.

Availability. HELOC availability is limited to Lendmire’s 16 full-service states, narrower than the 41-market DSCR footprint.

How Does a DSCR Cash-Out Refinance Take Out the Line?

Many investors plan the line as a bridge. Once the ADU is built and leased, the property has two units and a lease history, and a DSCR cash-out refinance can pay off the line. The refinance qualifies primarily on property-level rental income covering the payment, subject to lender guidelines.

On standard rentals, cash-out refinances typically top out around 75% LTV across most of the network, with about six months of seasoning expected. Coverage of 1.00 is where select programs start, and stronger ratios open better terms. A separate select-lender path goes below 1.00 with leverage and terms adjusted.

One caution: clearing 1.00 does not mean positive cash flow. DSCR compares rent to principal, interest, taxes, insurance and any association dues. Repairs, vacancy, management, utilities and capital costs sit outside the ratio. The complete DSCR loans guide covers how those programs work in more depth.

Key Terms Defined

• Combined LTV (CLTV): All loans secured by the property, divided by its value.
• Draw period: The stretch when you can borrow from the line and pay interest only.
• Lien position: Whether the lender is paid first or second if the property is sold.
• Automated valuation: A computer estimate of value, used in place of a traditional appraisal.
• Vesting: The way title is held, such as in your name or a revocable trust.
• DSCR: Rent divided by the full monthly property payment, used to qualify DSCR loans.

What Should You Ask Any Provider Before You Apply?

• Is the property eligible, and does it have to be in my own name or a revocable trust?
• What combined LTV applies to an investment property, and at which credit tier?
• Is the value automated, and what triggers a second valuation?
• How much of the line must be drawn at closing, and what are the later draw minimums?
• Does pricing float, and for how long?
• Do you require permits before an ADU can count?
• What is the exit plan if costs overrun?

Run these questions through a broker that shops multiple wholesale lenders and you can compare answers in one conversation instead of many.

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 is a mortgage broker arranging financing through select lenders in its wholesale network, with DSCR programs. You can reach the team at 828-256-2183. The calculator on this page gives an illustrative estimate only, not a quote, and all programs are subject to lender guidelines and full file review.

The ADU math rewards investors who check their equity first and who plan for the carry before the unit earns rent.

About Lendmire

Lendmire — NMLS# 2371349 — is a mortgage broker that arranges home equity lines of credit in its 16 full-service states through wholesale lenders, on primary residences, second homes and investment properties. Every line is subject to the lender’s guidelines and full underwriting. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. NerdWallet – HELOC on investment property

2. Fannie Mae ADU income sheet