Can You Get a HELOC to Build an ADU on Your Property?

The Quick Read: Yes, a HELOC can fund an ADU when you hold title personally or in a revocable trust and have enough equity left after your first mortgage, though a line on your primary home is far easier to get than one on a rental, and a property titled in an LLC cannot hold the line in Lendmire’s network. The line is sized on the value you own today. It gives no credit for the ADU’s future rent or value.

• Primary-residence and second-home lines reach 90% CLTV, only at a 720-or-better credit profile. An investment-property line tops out at 70% CLTV.
• Title must sit with an individual or a revocable living trust. LLCs, corporations and partnerships are not eligible.
• Equity, credit, and your debt-to-income ratio decide the size of the line, not rental coverage.
• Some investors build with the line, then refinance into a DSCR loan once the unit is permitted, finished, and rented.

Key Terms Defined

HELOC is a home equity line of credit, a revolving loan secured by property you already own.

ADU is an accessory dwelling unit, a second small home on the same lot, such as a backyard cottage or garage apartment.

CLTV is combined loan-to-value. It adds your first mortgage and the new line, then divides by the property’s current value.

Lien position is your lender’s place in line if the property is ever sold to pay debts. A HELOC usually sits behind the first mortgage.

DSCR is the debt service coverage ratio. It compares a rental’s monthly rent to its full monthly housing obligation: principal, interest, taxes, insurance, and any HOA dues.

Take-out loan is a loan that pays off an earlier one, usually after construction ends.

How Does a HELOC Pay for an ADU?

A HELOC works for an ADU because you borrow against equity you already hold. Nothing has to be built before the loan exists, so the line can be in place before construction begins.

Builders like the structure because costs arrive in stages: foundation, framing, systems, finishes. A line can suit that rhythm, with one limit in Lendmire’s network, described next.

Here is the catch. At least 75% of the line is drawn at closing. You do not get the pure draw-as-you-go experience some builders describe, so interest starts on most of the line right away. Pricing floats during both the draw and repayment periods and never converts to fixed.

The structure has two parts. On primary homes and second homes, one option is a 3-year interest-only draw followed by a 17-year repayment. The other is a 5-year interest-only draw followed by a 25-year repayment. Investment-property lines use the 5-year draw and 25-year repayment only. When the draw period ends, payments start paying down principal, so plan for that step up before you build.

Lines at or below $500,000 ordinarily run on an automated valuation, with no traditional appraisal. Anything above that needs a full appraisal. Lenders review your file on the interest-only payment calculated at the maximum draw, with a maximum debt-to-income ratio of 50%. Subject to lender guidelines and full file review, these are program ranges, not promises.

Which Property Secures the Line?

The property you pledge decides almost everything. Occupancy sets the credit floor, the leverage ceiling, and the maximum line.

Some details sit behind those headline numbers. On a primary residence, the 90% tier applies only at 720 or better and only for lines up to $500,000. At 700 or better, the ceiling is 85% for lines up to $500,000. A primary-residence line above $500,000 needs 700 or better (720 on the structure with the 5-year draw and 25-year repayment), caps at 75% CLTV, and requires a full appraisal.

Investment-property lines are the tight end of this market. White Coat Investor reports they are harder to get than primary-residence lines, and lists typical market requirements of a 720 score, 20% equity after a full draw, and a combined loan-to-value of 80% or less. In Lendmire’s network, an investment line stops at 70% CLTV with a 700 minimum score. Taxstra draws the same line between rental-property lines and primary-home lines, and RentalRealEstate.com likewise describes investment-property terms as stricter.

Availability is narrower than Lendmire’s DSCR footprint. The equity-line programs are offered in 16 full-service states, while DSCR financing covers 41 markets, including Washington, D.C.

How Much Can You Borrow? A Worked Example

Run the numbers on percentages first. The calculator on this page can convert them to dollars as an illustrative estimate.

Say you own a primary home with a first mortgage equal to 55% of its current value, and your credit sits at 720 or better. The 90% ceiling leaves room for a line worth up to 35% of value, capped at $500,000. If the first mortgage is 70% of value, the line room shrinks to 20%.

Now take a rental, with a first mortgage equal to 50% of value and a 700+ score. The 70% ceiling leaves room for a line worth up to 20% of value, again capped at $500,000.

Two points trip people up. First, the value used is today’s value, with no ADU on the lot. A future unit adds nothing to the sizing, and neither does the rent it might earn. Second, an equity line is sized on CLTV, occupancy, credit and your income. Rental coverage is not part of it.

Low equity is a common reason a line comes up short for an ADU. If the numbers do not stretch far enough, an after-renovation-value or construction product may fit better. Those are different loans, with more paperwork.

What If the Rental Is in an LLC?

Title is the sharpest dividing line for investors. The network’s equity lines must be held by an individual or a revocable living trust. Property already deeded to an LLC, corporation, partnership, or an irrevocable, blind, or land trust cannot hold the line. That is the biggest structural difference from a DSCR loan, which can be made to an LLC subject to lender program eligibility.

You have two choices. You can pursue a vesting change, which needs its own review with your attorney and lender. Or you can skip the HELOC and plan around a DSCR cash-out refinance, if the property is already finished and rentable.

Other edge cases deserve a quick look:

• An unpermitted ADU. Expect lenders to leave it out of both value and rent. Building without permits also breaks the later DSCR refinance.
• A short-term-rental ADU. A refinance on short-term-rental income generally needs about 12 months of hosting history, and the leverage tiers are lower. Short-term rental rules can vary by city, county, HOA, and property type, so confirm local rules before relying on projected rental income.
• Exposure limits. A borrower is limited to three lines. An owner of more than 15 financed properties is not eligible.
• Ineligible property types. Manufactured homes, log homes, and barndominiums are not offered in the network’s equity-line or DSCR programs. Condos, townhomes, PUDs, single-family homes and 2-4 unit properties are eligible.

The Take-Out: Where DSCR Comes In

A DSCR loan does not build your ADU. It is a take-out loan on a finished, rentable property, so it works after construction, not during it.

Lenders order an appraisal that produces two numbers. Value sets the loan-to-value ratio, and market rent sets the coverage ratio. Appraisers use the 1007 rent schedule on a single-family home and the 1025 income report on a 2-4 unit property. Those are only form names, since DSCR loans are not agency products.

The ADU’s rent counts only when the unit is permitted, finished, and supported by a lease or an appraiser’s market rent. A planned unit with no certificate behind it earns nothing in the calculation.

Cash-out tops out around 75% LTV on standard rentals and around 70% on short-term-rental collateral, with about 6 months of seasoning as the common expectation. Appraised value, not build cost, sets how much cash comes out, and an ADU can appraise below what it cost. Cash-out proceeds also do not satisfy reserves, which commonly run around 6 months of PITIA and vary by lender, leverage, and loan size.

On coverage, 1.00 is where many select programs start, and a stronger ratio can open better pricing and leverage. A separate select-lender path goes below 1.00, with leverage and terms adjusted. Clearing 1.00 is not the same as positive cash flow, because repairs, vacancy, management, utilities, and capital costs all sit outside the calculation.

Investors with thin personal income but strong rents often prefer this route after the build, because DSCR qualifies primarily on property-level rental income covering the payment, subject to lender guidelines. Lendmire’s complete DSCR loans guide covers the full qualification picture.

When a HELOC Is the Wrong Tool

Skip the HELOC when any of these describe your situation.

• The rental sits in an LLC. The network’s lines cannot be held there.
• Your equity is thin. A small line cannot cover a full build, and a capped line leaves no room for overruns.
• Your plan depends on build cost coming back out. The appraisal may land below what you spent, so do not plan the later refinance around the construction bill.
• You cannot absorb a payment jump. Floating pricing and the move from interest-only to full repayment can both raise your obligation mid-project.

Before you pick a lender, ask five questions. What is the maximum CLTV for my occupancy and credit? How much of the line is drawn at closing? Does pricing ever convert to fixed? What happens when the draw period ends? Does the lender need a defined scope for construction draws?

Your Next Step

The strongest plans pass both tests: enough equity for the build, and enough rental coverage for the refinance afterward. 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 broker that arranges financing through select lenders in its wholesale network, and every figure here is subject to lender guidelines and full file review, not a commitment to lend.

About Lendmire

Lendmire (NMLS# 2371349) is a mortgage broker. Home equity lines of credit — on a primary residence, a second home or an investment property — are arranged through wholesale lenders in Lendmire’s 16 full-service states, and every line is underwritten by the lender under its program guidelines. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. White Coat Investor — HELOC on Investment Property

2. Taxstra — HELOC on Investment Property

3. RentalRealEstate.com — HELOC Loans for Rental Property