Should a Homeowner Use a HELOC to Build an ADU or Pool?

The Quick Read: It depends on the project: a HELOC can be a reasonable way to fund an ADU that will produce rent, and it is a weaker fit for a pool that produces nothing, provided the equity cushion is real and the borrower can carry a payment that floats.

• An ADU can earn income. A pool is mostly a lifestyle purchase financed against the house.
• Market data reports that an inground pool recoups roughly 56% of its cost at resale.
• On Lendmire’s network, equity lines on a primary residence run up to 90% CLTV, and only at a 720-or-better credit profile.
• Investment-property lines top out at 70% CLTV and $500,000.
• The strongest files clear two tests: enough equity and enough payment capacity.

Straight Answer: ADU Yes, Pool Rarely

For an investor, the ADU is the easier case. It can add rent, and rent is the one thing that pays a debt back. A pool adds a payment and no income.

Take an ADU first. A homeowner with real equity who plans to rent the unit has a clear repayment story. The catch is value. Appraisers often credit an ADU below what it cost to build, so the equity you borrowed against may not be rebuilt by the finished project.

A pool is different. You may still want one. Just recognize that you are spending equity on enjoyment, not on an asset that pays you.

How a HELOC Works for a Build

A HELOC is a revolving line secured by the home. You draw as costs come due, and you pay interest on what you have drawn. That draw-as-you-pay shape matches construction, where money goes out in phases: design, permits, foundation, framing, finishes.

On the programs Lendmire places files with, the structure is a standalone line in first or second lien position. Borrowers on primary residences and second homes can choose a 3-year interest-only draw followed by a 17-year amortizing repayment, or a 5-year draw followed by 25 years of repayment. Investment lines use the 5-year draw and 25-year repayment structure only. Pricing floats during both periods and does not convert to fixed.

Two details matter for a build. At least 75% of the line is drawn at closing, so this is not a pure pay-as-you-go line. And later draws carry a $1,000 minimum, with a higher minimum in Texas. Both are subject to lender guidelines, and each figure applies only within its own program’s terms.

Here is the catch with sizing. Lenders generally size the line on the house as it stands today. As FirstClose, an industry vendor, notes, many lenders underwrite on current value alone, without crediting the future ADU. Your line reflects the house you have, not the house you are building.

How Much Can You Borrow?

Borrowing capacity comes from equity, credit, and debt-to-income. Equity is the home’s value minus what you owe on the first mortgage, and the combined loan-to-value ceiling caps the total.

The ceilings depend on occupancy, so the answer for your project depends on which house you are borrowing against.

Lower credit tiers step the ceiling down. A primary residence at 640 tops out around 80% CLTV, for example. A line above $500,000 is for primary residences only, calls for a 700 credit profile or better (720 on the longer-runway structure), caps at 75% CLTV, and requires a full appraisal.

Other qualifiers worth knowing:

• Debt-to-income tops out at 50%, and at 45% for profiles from 600 to 679.
• The minimum credit score is 600, though the minimums for second homes and investment lines vary by scenario.
• Lines at or below $500,000 usually run on an automated valuation, and a borrower can request a full appraisal.
• Title must sit with the individual or a revocable living trust. An LLC cannot hold title on these lines.
• Lendmire’s HELOC availability covers 16 full-service states, which is narrower than its 41-market DSCR footprint.

Broader surveys of the market often report equity-line ceilings higher than a given lender’s; those describe the market at large, not this network’s tiers.

Run a quick sizing check before you design anything. Take the home’s current value, apply the CLTV ceiling for your credit tier, then subtract the first mortgage balance. What remains is the most you could draw. Then ask whether the project cost, plus a buffer for overruns, fits inside that number with room to spare.

ADU or Pool: Side by Side

An above-ground pool is a separate matter. Opendoor explains that above-ground pools are generally treated as personal property and rarely add appraised value. Climate also swings the outcome. A pool tends to earn its keep in warm regions where residents expect one, and less elsewhere.

A pool may support a higher appraised value, depending on comps and underwriter review. Treat any appraisal lift as upside, not as the repayment plan.

The Investor Angle: Two Different Loans

An equity line and a DSCR loan answer different questions. The HELOC asks whether you, with your credit and your equity, can carry the line. A DSCR loan is reviewed primarily on property-level rental income covering the payment, subject to lender guidelines. Our complete DSCR loans guide covers how that second test works.

Many investors use the two in sequence. Build the ADU with a HELOC drawn against a primary residence. Once the unit is permitted, finished, and rented, the property now has rent evidence. A DSCR cash-out refinance can then replace the line, qualifying on the property’s income rather than on your personal debt-to-income.

That exit has friction. A HELOC second lien complicates a later refinance, because the new first loan must pay off or subordinate it. Plan for the payoff. If an existing DSCR first mortgage sits on the property, read the note first, since some loans limit additional liens.

On the DSCR side, cash-out refinances on standard rentals generally top out around 75% LTV across most of the network, with about six months of seasoning as the common expectation. Coverage of 1.00 is where select programs start, and a separate select-lender path takes coverage below 1.00 with leverage and terms adjusted. A pool adds nothing to that coverage ratio. An ADU can, if the lender’s rent analysis credits it. Keep in mind that clearing 1.00 is not the same as positive cash flow, because repairs, vacancy, and management sit outside the calculation.

Flip point: if your numbers only work when the ADU rents at the top of the range, borrow less or wait. A HELOC with a floating payment and an optimistic rent assumption is the combination that hurts.

Where This Goes Wrong

Rental use can conflict with the line’s own terms. The CFPB’s HELOC booklet warns that renting your home to others may be prohibited under the terms of a line of credit. Read the agreement before you build a rental unit.

Other failure points:

• Payment shock. A floating payment can rise, and the line moves from interest-only draws to full amortization when the draw period ends.
• Cost overruns. Size the line to the project plus a buffer. Don’t draw for anything else.
• Stalled permits. A unit you cannot legally rent is a payment with no income.
• Sale triggers payoff. If you sell, the line is generally due in full.
• Collateral risk. The home secures the debt, so missed payments can end in foreclosure.

Pool buyers face a quieter risk. The pool payment arrives alongside ongoing maintenance, and neither earns any income.

HELOC vs. the Alternatives

A HELOC suits a project with uncertain or phased costs. For a fixed cost, a closed-end home equity loan or a cash-out refinance may fit better. If a cash-out would replace a good first-mortgage structure, keep that structure and add a second lien instead.

Tax treatment varies; consult a qualified professional before relying on any deduction.

Key Terms Defined

CLTV: Combined loan-to-value, meaning all loans against the home divided by its value.

Draw period: The stretch when you can borrow from the line and pay interest only.

Repayment period: The later stretch when the balance amortizes and the payment jumps.

ADU: An accessory dwelling unit, a separate legal living space on the same lot.

DSCR: Debt service coverage ratio, the property’s rent divided by its monthly debt obligation.

Before You Apply

1. Confirm zoning and permits before you borrow.

2. Get contractor bids and add a contingency buffer.

3. Check your CLTV ceiling at your credit tier and occupancy.

4. Read your existing mortgage terms for lien limits.

5. Decide the exit: payoff from cash flow, a refinance, or a DSCR cash-out.

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.

Every figure above is subject to lender guidelines and a full file review, and nothing here is a commitment to lend.

About Lendmire

Lendmire (NMLS# 2371349) is a mortgage brokerage serving homeowners and real estate investors in its 16 full-service states. Home equity lines of credit are arranged through wholesale lending channels; Lendmire brokers the line and the lender underwrites each application under its occupancy-based guidelines. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

Investors who want the broader program framework can review how DSCR loans work.

References

1. FirstClose, ADU financing

2. Opendoor pool value

3. CFPB, HELOC booklet