The Quick Read: For an ADU on a rental held in your name, the best program for your situation is usually a standalone investment line capped at 70% CLTV, sized on the property as it stands today, used to fund the build and later replaced by a DSCR refinance once the unit is permitted and rented.
- The line is sized on today’s property value and your credit, not on the finished ADU or its future rent.
- On an investment property, the ceiling is 70% CLTV, the credit floor is 700, and the maximum line is $500,000, subject to lender guidelines.
- Title must sit in your name or a revocable living trust. An LLC cannot hold it.
- The ADU needs to be legal and permitted, or it may count for nothing at the take-out stage.
- A DSCR loan is generally the exit, not the construction funding.
What This Loan Is, and What It Isn’t
An investment-property HELOC is a personal loan secured by a rental. A HELOC (home equity line of credit) lets you borrow against equity, which is value minus what you owe. The lender looks at your credit, your debt load, and the equity in the property. It does not ask whether the rent covers the payment.
How large a line the equity supports.
An equity line is sized by combined loan-to-value, occupancy, and credit — not by rental coverage. Switch the occupancy or the credit band and the ceiling moves with it.
Investment-property lines require a 700 minimum credit score; second-home lines start at a 640 minimum and primary-residence lines at 600, and the combined-LTV ceiling steps down as the credit band drops on primary-residence and second-home lines and holds on investment-property lines; the line cap steps down on primary-residence lines and holds at every tier on investment-property and second-home lines.
A debt-to-income ratio above 45% requires 680+ credit. Profiles under 640 are limited to single-family homes. At least 75% of the approved line is drawn at closing. Ceilings, floors, and caps update from Lendmire’s centralized guideline source.
Line estimate
Illustrative estimate only — not a quote, Loan Estimate, approval, or commitment to lend. The rate is an editable assumption; equity-line pricing is variable through both the draw and repayment periods and never converts to fixed. Occupancy and credit drive the ceiling together: an investment property tops out at 70% combined LTV (minimum credit 700, line cap $500,000); a second home tops out at 90% combined LTV (minimum credit 640, line cap $500,000), with the ceiling stepping down as the credit band drops (the cap holds at every tier); a primary residence tops out at 90% combined LTV (minimum credit 600), and its $750,000 maximum line is available only at 75% combined LTV or below with a 700-or-better credit profile (720 on the longer-runway program) and a full appraisal. Lines above $500,000 require a full appraisal. Credit, debt-to-income, property type, and full underwriting review all affect the final line.
That is the line between this product and a DSCR loan. DSCR stands for debt service coverage ratio. It compares a property’s monthly rent to its monthly housing payment. A DSCR loan is reviewed primarily on property-level rental income covering the payment, subject to lender guidelines. A HELOC qualifies you, the borrower.
So which one funds an ADU? Usually the HELOC pays for construction, and the DSCR loan comes later. A DSCR loan needs a finished, rentable property. It generally cannot fund raw construction. Lendmire’s complete DSCR loans guide covers that second half of the plan in depth.
There is no single winner here. The best program for your situation turns on four things: whether the ADU is legal, how much usable equity you have, how the title is held, and what you plan to do once the unit is built.
Lendmire is a mortgage broker, not a lender. It places these files with wholesale HELOC lenders and matches the scenario to the program. HELOC placement runs through 16 states, a narrower footprint than the DSCR platform’s 41 markets, including Washington, D.C.
How Underwriting Treats an ADU Line, Step by Step
Here is the sequence a lender follows. Every step can stop the file.
1. Occupancy and property type. The line must be on a rental you own, and the property must be an eligible type. Single-family homes, 2-4 units, PUDs, townhomes, and condominiums (including non-warrantable ones) are eligible, subject to lender guidelines.
2. Title. The lender checks who holds title. More on this below, because it ends more files than anything else.
3. Credit. On an investment property, the floor is 700. Both 700 and 720 reach the same 70% CLTV, so a higher score buys eligibility rather than extra leverage.
4. Debt-to-income (DTI). DTI compares your monthly debts to your income. The maximum is generally 50%, and the lender reviews your file on the interest-only payment calculated on the maximum draw. That is a heavier test than the money you actually pull on day one.
5. Valuation. Lines at or below $500,000 ordinarily use an automated valuation, with no traditional appraisal. You can request a full appraisal. Either way, the value reflects the property today.
6. The equity test. The lender adds your existing mortgage and the new line, then compares the total to the CLTV cap.
7. Closing and draw. At least 75% of the line is drawn at closing. After that, the minimum subsequent draw is generally $1,000.
Notice what is missing. Nothing in that list counts the ADU you have not built yet. The line rests on the equity you already have.
A Sizing Example in Percentages
CLTV means combined loan-to-value: your first mortgage plus the new line, divided by the property’s value. Here is the math using modeled percentages, not market data.
Say your existing mortgage equals 45% of the property’s value. The investment cap is 70% CLTV. That leaves room for a new line worth up to 25% of the property’s value, subject to the $500,000 maximum and lender review.
If your mortgage equals 60% of value, room shrinks to 10%. If it equals 70% or more, there is no room at all. A line can sit in first or second lien position, so a paid-off rental has the most space. A rental with an existing low-cost first mortgage keeps that mortgage intact when you add a second-lien line.
The ADU cost has to fit inside that room. If it does not, the plan changes. Thin equity or a large detached build often points toward a construction or renovation loan, which is sized on after-completed value and releases money in stages. That is a different product from an equity line.
The Draw Structure Matters More Than Most Investors Expect
Investment lines run one structure only: a 5-year interest-only draw period, then a 25-year fully amortizing repayment. Pricing floats during both periods and never converts to fixed.
The CFPB’s HELOC explainer describes the general pattern: you borrow during a draw period, then repay on a set schedule. It warns that payments are often much higher in repayment. In some plans the whole balance can come due when repayment begins. The agency’s HELOC brochure adds that payments can change even when you draw nothing more.
Here is the catch for builders. The popular pitch for a HELOC is that you borrow only as you spend. On this network, at least 75% of the line is drawn at closing. You start paying interest on most of the line before the first wall goes up. Build that carry into your budget, along with the months between finishing the unit and signing a tenant.
A practical rule: size the line to the build, not to the maximum. Smaller is cheaper to carry.
Why Future ADU Rent Doesn’t Qualify the Line
Lenders do not count rent from a unit that does not exist. They also do not credit it afterward, because the HELOC never tested rent in the first place. Your income and the equity decide the line.
Rent matters at the next stage, when you refinance into a DSCR loan. At that point, the appraiser documents rent on a rent schedule. Form 1007 is the standard form for a single-family property. Forms 1025 and 216 apply to 2-4 unit properties.
Permits decide whether any of this works. A finished unit needs a building permit, a final inspection, or a certificate of occupancy before it counts as legal. BuildWithAPlan notes that an appraiser cannot count square footage that was never signed off. ADU Zoning’s financing guide makes the same point from the other side: a permitted unit can add value, and an unpermitted one may add none.
A permitted ADU may support a higher appraised value, depending on comps and underwriter review. Do not plan around any specific lift.
Structures and Variations
Investors fund ADUs several ways. This table compares the five common routes.
| Option | Underwritten on | Lien | Fit |
|---|---|---|---|
| Investment HELOC | Your credit, DTI, equity | First or second | Keeping a low-cost first mortgage |
| Home equity loan | Your credit, DTI, equity | Second | Fixed build cost, lump sum |
| Cash-out refinance | Borrower or property, by program | Replaces first | Resetting the whole loan |
| DSCR cash-out | Rent vs. payment | Replaces first | Existing rentals with strong coverage |
| Construction loan | After-completed value | Varies | Thin equity, large builds |
A few notes on the table.
A second-lien product leaves your first mortgage alone. A cash-out refinance replaces it, so the whole balance reprices. If your current first mortgage is a good one, that points toward a second lien. If it is not, a cash-out refinance is worth modeling.
On a DSCR cash-out refinance of a standard rental, leverage tops out around 75% LTV across most of the network, and lenders commonly expect about 6 months of seasoning. For a short-term-rental property, cash-out is limited to 70%, not the 75% available on a standard rental. DSCR loans are for non-owner-occupied investment property. Because they are business-purpose loans, they are reviewed differently from an owner-occupied mortgage.
Where the General Rule Breaks
An LLC owns the rental. This is the sharpest edge. The HELOC title must be held by you as an individual or by a revocable living trust. LLCs, corporations, partnerships, and irrevocable, blind, or land trusts cannot hold title. If your rental is already deeded to an LLC, you need a vesting change or a DSCR cash-out instead. A DSCR loan is the product that can lend to an entity, subject to program terms.
The ADU is unpermitted. Years of rental history do not make a unit legal. Appraisers look to permits and zoning, and DSCR lenders follow the appraiser. Treat legalization as step one, not an afterthought.
The ADU will be a short-term rental. Form 1007 is a long-term rent schedule. Class Valuation argues it cannot support short-term-rental income, and using it can produce an artificially low coverage number. Short-term-rental collateral needs its own income method. On the DSCR side, expect about 12 months of hosting history, and a floor of 1.00 on refinances. 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.
The property type doesn’t fit. Manufactured homes, co-ops, condotels, log homes, commercial, mixed-use, and agricultural zoning are not eligible for the HELOC. On the DSCR side, manufactured homes (single- and double-wide), log homes, and barndominiums are not offered. If your ADU is a manufactured unit, plan another route.
The ADU sits on a 2-4 unit rental. Eligible, but the details change.
You hold several lines. A borrower is limited to three lines. Combined exposure caps at $2,000,000 on the higher-leverage program and $750,000 on the longer-runway program. Owning more than 15 financed properties makes you ineligible. A property listed for sale, or listed within the past 60 days, is ineligible in several states.
Your income is self-employed. Bank statements can document income, but on an investment line they are never the binding constraint, because the 700 credit floor sits above the 680 bank-account minimum. Lendmire’s article Best Bank Statement HELOC Program for an Accessory Dwelling Unit covers that route.
Which Setup Fits Which Situation
| Your situation | Likely fit |
|---|---|
| Rental in your name, solid equity, 700+ credit | Investment HELOC to build |
| Rental in an LLC | DSCR cash-out, or change vesting first |
| Thin equity, large detached build | Construction loan |
| Credit below 700 | Different route, since 700 is a hard floor |
| Strong rent coverage on existing units | DSCR cash-out refinance |
| Need a line above $500,000 | Not on an investment property |
The last row catches people. A line above $500,000 is primary-residence only. On an investment property, the maximum is $500,000, and CLTV tops out at 70%.
Planning the Exit Before You Build
Treat the HELOC as the bridge. The permanent plan is the DSCR refinance.
Run that refinance in your head before you draw a dollar. Most DSCR purchase files land at 75%-80% LTV, and cash-out on a standard rental runs around 75%. Credit expectations are around 660 for most programs, with a 620 floor in parts of the network. A 700+ score opens the strongest leverage tiers.
Coverage is where rent meets the payment. A 1.00 ratio is where many select programs start, never a universal standard. A separate select-lender path takes coverage below 1.00, with leverage and terms adjusted. Stronger coverage opens better pricing and leverage.
Reserves vary by lender, leverage, loan size, and transaction type. Around 6 months of PITIA is common, and loans above $1,500,000 typically step up to about 9 months. PITIA means principal, interest, taxes, insurance, and any HOA dues.
One warning. Clearing 1.00 is not the same as positive cash flow. DSCR compares rent to PITIA only. Repairs, vacancy, management, utilities, and capex sit outside it.
Key Terms Defined
ADU (accessory dwelling unit): A second, smaller home on the same lot as the main house, such as a garage conversion or a backyard cottage.
CLTV (combined loan-to-value): Your first mortgage plus the new line, divided by the property’s value.
Draw period: The stretch when you can pull money from the line, paying interest only on this network’s investment lines.
DSCR (debt service coverage ratio): Monthly rent divided by the monthly payment on the property.
PITIA: Principal, interest, taxes, insurance, and any HOA dues.
Vesting: How title to the property is held, such as in your own name, a revocable trust, or an LLC.
Take-out: The permanent loan that pays off short-term construction funding.
Frequently Asked Questions
Can an investor use a HELOC to build an ADU?
Yes, on an eligible rental held in your name or a revocable trust. On an investment property, expect a 70% CLTV ceiling, a 700 credit floor, and a $500,000 maximum line, all subject to lender guidelines. The line is sized on today’s value, so existing equity has to cover the build.
Does the ADU’s future rent count toward qualifying?
No. A HELOC underwrites you and your equity, not the rent. Rent counts later, when a DSCR refinance documents it on the appraiser’s rent schedule. For that, the unit generally has to be finished, permitted, and leased.
Can I use an LLC?
Not for the HELOC. LLCs, corporations, partnerships, and several trust types cannot hold title. If an LLC owns the rental, you need a vesting change or a DSCR cash-out. A DSCR loan can lend to an entity, depending on program guidelines.
Can a DSCR loan fund the build?
Generally no. The usual sequence is a line to build, then a DSCR refinance once the unit is permitted, rented, and appraised.
What happens when the draw period ends?
On an investment line, the 5-year interest-only draw ends and a 25-year repayment begins. Payments step up because you start repaying principal, and because pricing floats, they can move even without new draws. Plan the refinance well before that point.
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. The ADU you build is only as financeable as its permit, so start with the paperwork.
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.
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Informational only. Not a Loan Estimate, approval, or commitment to lend. Program availability and eligibility are subject to lender guidelines, credit approval, property review, and underwriting.
References
3. BuildWithAPlan – ADU appraisal
4. ADU Zoning – ADU financing guide
5. Class Valuation – Form 1007 and short-term rentals
This article is part of Lendmire’s investment property HELOC program — full qualification details, guidelines, and scenarios live on the program page.
Related reading: Best DSCR HELOC Program on an Airbnb You Hold as an Investment · Best DSCR HELOC Program to Buy Rental Property · Best DSCR HELOC Program on an Investment Property You Own
Brandon Miller
Founder & CEO, Mortgage Loan Originator, Lendmire LLC
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Legal disclosures. Lendmire (NMLS# 2371349) is a state-licensed mortgage brokerage that arranges financing through wholesale lender relationships. Lendmire is not a direct lender, depository institution, or registered financial advisor. The discussion above is general informational content about real estate financing — it is not financial, legal, or tax advice, and readers should consult licensed professionals for guidance on their individual circumstances. Loan inquiries are subject to lender underwriting; this article does not represent a commitment to lend. Loan terms, rates, and qualification standards vary by borrower, property, and state, and are subject to change at any time. Equal Housing Opportunity. NMLS Consumer Access: nmlsconsumeraccess.org.