What to Expect on a HELOC When Your Home Has an Unpermitted Basement Apartment

The Quick Read: Usually, you can still get a HELOC, but the unpermitted unit will likely add little or no value to the appraisal and no usable rent to the file. The line is sized on the legal, permitted footprint of the house, so the lender follows what the appraiser reports, not what the unit collects.

• The appraiser’s treatment of the unit sets the value, and the value sets the line.
• Rent from an unpermitted unit generally does not help you qualify.
• Network ceilings depend on occupancy and credit profile: an investment property is capped at 70% CLTV, a primary residence with a more modest credit profile reaches a lower tier, and up to 90% CLTV is available only on a primary residence or second home at a 720-or-better credit profile.
• A line can later be frozen or reduced if value falls or finances change.
• Legalizing the unit first is the cleanest way to bring in value and rent.

This applies to lines Lendmire’s wholesale network places in its 16 full-service states. That is narrower than the 41-market DSCR footprint. Every figure here is subject to lender guidelines and full file review, and none of it is a commitment to lend.

How Does the Appraisal Treat an Unpermitted Basement Unit?

The appraiser decides how the unit is treated, and the lender generally follows. Expect the unit to be reported as unpermitted space and given little or no contributory value, because supporting comparable sales rarely exist.

Fannie Mae is not the rulebook for these lines. Still, its Selling Guide on appraisal improvements shows how appraisers think. It tells them to comment on the quality and appearance of an addition built without a permit, and on its effect, if any, on market value. It does not impose a blanket exclusion. Outcomes depend on the appraiser and the comps.

Two other details matter. Unpermitted space often loses value for physical reasons, not paperwork. It is usually below grade, or it fails the ceiling-height test for finished living area. And a unit can sometimes reduce value, not just add nothing, when the appraiser treats it as a liability.

On most files in the network, lines at or below $500,000 ordinarily run an automated valuation. An automated tool cannot see a basement unit. A lender can still order a full appraisal, and a borrower can ask for one. A line above $500,000 requires a full appraisal on every file.

What Changes in the Application Process?

The unit surfaces at the property review and the appraisal. Describe the property accurately on the application.

The steps run in this order:

1. Application and disclosure. You describe the home, including the basement space and how it is used.

2. Valuation. An automated valuation or a full appraisal is ordered, depending on the line size and the lender’s judgment.

3. Appraiser’s report. The appraiser measures finished area, reports below-grade space separately, and notes the missing permit.

4. Value and CLTV. The lender applies its combined loan-to-value ceiling to the appraised value, then subtracts existing liens. If the unit is excluded from value, the line shrinks.

5. Conditions. A lender may ask for safety fixes such as egress, smoke and carbon monoxide detectors, or electrical corrections. Title and the first-lien payoff position are also reviewed.

6. After the line is open. The line stays tied to the home’s value and your finances, as covered below.

What Network Ceilings Apply to the Line?

Ceilings depend on how you occupy the home. On an investment property, the network ceiling is 70% CLTV, and there is no tier above it.

• Primary residence at 720: a choice between 90% CLTV up to $500,000, or a larger line up to $750,000 at a reduced CLTV. Both options apply to primary residences only.
• Lines above $500,000: primary residence only, with a full appraisal, a reduced CLTV cap, and a credit profile of 700 or better (720 on the longer-runway structure).
• Line size overall: $25,000 to $750,000, in first or second lien position.
• Credit floor: 600 on a primary residence, with 640 on second homes and 700 on investment properties.
• Draw structure: a 3-year interest-only draw with a 17-year repayment, or a 5-year draw with a 25-year repayment. Investment lines use the 5-year draw only.

Because the unit may add nothing to value, it is safest to size your plan on the legal footprint alone. If a unit-inclusive value arrives, treat it as a bonus.

Does Rent From the Unit Count?

Rent from an unpermitted unit generally does not count. The appraiser’s market-rent exhibit has to support rent on a legal unit, and an unpermitted one usually cannot. Collected rent does not override the appraisal.

For a primary residence, this matters less. A HELOC there is qualified on your income and a debt-to-income ratio, with 50% as the maximum and 45% for credit profiles from 600 to 679. The basement rent is not the thing carrying the file.

The picture changes on an investment property, where rental coverage drives the analysis. DSCR compares rent to the full housing payment (principal, interest, taxes, insurance and any association dues). If the unit’s rent drops out of the numerator, a ratio that looked healthy can fall short. Clearing 1.00 on legal rent alone is also not the same as positive cash flow, since repairs, vacancy, management and utilities sit outside the calculation. Most DSCR programs want to see coverage at or near 1.00, and a separate select-lender path takes coverage below 1.00 with leverage and terms adjusted. The complete DSCR loans guide covers how the ratio is built.

Unpermitted Is Not the Same as Illegal

Permit status and zoning compliance are separate questions. An appraiser reports zoning as legal, legal non-conforming, illegal, or no zoning. A grandfathered basement unit with records is a different file from an unpermitted one.

Fannie Mae’s guide illustrates the point for its own loans. A unit that does not comply with zoning can still be eligible there if it conforms to the neighborhood, is appraised at its current use, is disclosed, and is supported by at least two comparable sales. That is agency material for contrast only. A non-agency lender sets its own rules, and many give the unit little credit regardless.

Documents that help include:

• Permit history or a certificate of occupancy.
• As-built plans.
• Photos of egress, ceiling height and the kitchen area.
• Proof of any prior legalization work.

Property and Title Limits Worth Knowing First

The line’s property and vesting rules can stop a file before the unit even comes up.

• Eligible: single-family, 2-4 units, PUD, townhome and condominium, including non-warrantable. Modular homes are eligible only on the longer-runway structure.
• Not offered: manufactured homes, co-ops, condotels, log homes, and commercial, mixed-use or agricultural zoning.
• Title: held by you as an individual or in a revocable living trust. An LLC cannot hold title on this product, which is the sharpest difference from a DSCR loan. A home already deeded to an LLC needs a vesting change, or a DSCR cash-out instead.
• Limits: up to three lines per borrower, and no more than 15 financed properties.
• Credit: a report no more than 90 days old at closing, with no rescores.

What Happens After the Line Opens?

A HELOC is not permanent once approved. The FTC explains that a lender may freeze or reduce a line if the home’s value falls significantly below the appraised amount, or if it reasonably believes a material change in finances will keep you from paying.

Note the network’s own draw rules too. Most of the line must be drawn at closing, and the minimum later draw is $1,000, with Texas at $4,000 on the program that states it. Pricing floats during both the draw and repayment periods and never converts to fixed.

Legalize First, or Borrow First?

If local code allows it, legalizing before you apply is the cleanest path. It can bring in value and rent. Whether it is possible depends on egress, ceiling height and zoning, and a contractor or the building department can tell you that.

An investor with a legal basement unit and a documented lease can pursue a DSCR cash-out refinance that prices the unit properly. Lendmire’s network generally caps standard-rental cash-out at 75% LTV and short-term-rental cash-out at 70%, with about six months of seasoning as the common expectation. On the equity-line side, Lendmire’s piece What to Expect When a HELOC Funds Your Next Home’s Down Payment explains how a line is used as capital.

A rough decision path:

1. Confirm the unit’s legal status with the local building department.

2. If legalization is feasible, price the work against the equity you need.

3. Reappraise after the work, then apply.

4. If legalization is not feasible, plan the line on the legal footprint and treat the unit as no value and no income.

Key Terms Defined

CLTV: combined loan-to-value, which is all liens on the home divided by its appraised value.

Unpermitted unit: living space built or converted without the required local permits.

Legal non-conforming: a use that was lawful when built but no longer matches current zoning.

Below-grade space: finished area below ground level, usually reported separately from above-grade living area.

DSCR: a ratio of rent to the full housing payment.

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.

About Lendmire

Lendmire, NMLS# 2371349, is a mortgage brokerage that arranges home equity lines of credit through wholesale lending partners in its 16 full-service states. Lines on primary residences, second homes and investment properties are each reviewed individually by the lender under the program’s occupancy, credit and combined-loan-to-value guidelines. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. Fannie Mae Selling Guide B4-1.3-05

2. FTC, Home Equity Loans and HELOCs