DSCR Loans for Garage Conversions and ADUs

Garage conversions and accessory dwelling units (ADUs) have become one of the fastest-growing segments in residential real estate. California alone has permitted over 90,000 ADUs since 2017. Texas, Florida, Oregon, and Washington have passed sweeping ADU-friendly legislation. The economics are simple: add a rentable unit to an existing property for a fraction of what new construction costs.

For investors, the financing question has always been the sticking point. Conventional lenders don't love ADU projects — the loan-to-value calculations get messy, the income isn't always recognized, and the underwriting process drags on for months.

DSCR loans cut through that. They evaluate the property's total rental income against its total debt payments. If the numbers work, you get the loan. No tax returns, no W-2 verification, no explanation of why your Schedule E shows a loss.

What Counts as a Garage Conversion or ADU?

Before diving into financing, let's clarify what we're talking about:

Garage Conversions

Taking an existing attached or detached garage and converting it to livable space. This can be:

• Full conversion: The entire garage becomes a studio or one-bedroom apartment
• Partial conversion: One bay of a two-car garage is converted while retaining one parking space
• Two-story conversion: Adding a second story above the garage for the living unit

Accessory Dwelling Units (ADUs)

A broader category that includes garage conversions but also:

• Detached new construction: A separate small building on the same lot
• Basement conversions: Converting below-grade space to a separate unit
• Attached additions: Adding onto the primary structure
• Junior ADUs (JADUs): Smaller units (under 500 sq ft) created within the existing footprint of the primary home

For DSCR loan purposes, the type of ADU matters less than the outcome: a permitted, rentable unit that generates verifiable income.

Garage Conversion Costs: What to Actually Budget

Garage conversions are the most cost-effective way to add a rental unit. Here's what they actually cost in 2025-2026:

Basic Garage Conversion (400-500 sq ft studio)

• Foundation and structural: $3,000 - $8,000 (most garages need minimal work)
• Insulation and drywall: $4,000 - $8,000
• Electrical (panel upgrade + circuits): $3,000 - $6,000
• Plumbing (kitchen + bathroom): $8,000 - $15,000
• HVAC (mini-split): $3,500 - $6,000
• Flooring: $2,000 - $5,000
• Kitchen (cabinets, counters, appliances): $5,000 - $12,000
• Bathroom (fixtures, tile, vanity): $4,000 - $10,000
• Windows and doors: $2,000 - $5,000
• Permits and plans: $2,000 - $8,000
• Contingency (15%): $5,500 - $13,000

Total: $42,000 - $96,000

The national average for a garage-to-apartment conversion sits around $60,000-$70,000. In high-cost markets (LA, SF, NYC metro), expect $80,000-$120,000. In lower-cost markets (Phoenix, Dallas, Atlanta), $40,000-$65,000 is realistic.

Detached ADU New Construction (600-800 sq ft)

New construction ADUs cost more but offer more flexibility in design and placement:

• Total cost range: $120,000 - $250,000
• Prefab/modular ADUs: $90,000 - $180,000 (installed)
• Per square foot: $200 - $350

Return on Investment

The math on garage conversions is compelling:

• Conversion cost: $65,000
• Monthly rent: $1,200 - $1,800
• Annual gross rent: $14,400 - $21,600
• Simple payback period: 3-4.5 years
• Property value increase: $80,000 - $150,000 (appraised value of the additional unit)

You're spending $65,000 to add $80,000-$150,000 in property value and $14,000-$21,000 in annual rental income. That's why investors are doing this at scale.

How DSCR Loans Work for ADU Properties

When you apply for a DSCR loan on a property with an ADU, the lender evaluates the total property income — primary unit rent plus ADU rent — against the total mortgage payment.

The DSCR Calculation for ADU Properties

Example: Single-family home with garage conversion ADU

• Primary home rent (if rented): $2,200/month

• ADU rent: $1,400/month

• Total gross monthly rent: $3,600

• Annual gross rent: $43,200

• Vacancy and operating expenses (30%): -$12,960

• Net operating income: $30,240

• Property value: $450,000

• DSCR loan at 75% LTV: $337,500

• Rate: 7.5%, 30-year fixed

• Annual debt service: $28,320

• DSCR: $30,240 ÷ $28,320 = 1.07

That's a passing DSCR at most lenders. With slightly higher rents or a better rate, you'd clear 1.20 comfortably.

Owner-Occupied vs. Investment Property

This distinction matters for DSCR loans:

• Investment property (both units rented): Full rental income from both units counts toward DSCR. This is the standard investment DSCR loan scenario.
• Owner-occupied with ADU: Some DSCR lenders won't count the primary unit as income if you live in it. You'll need a lender that considers the ADU income alone or uses fair market rent for the primary unit.

For investors buying specifically as rental properties, this isn't an issue. Both units generate income.

State-by-State ADU Regulations That Matter

ADU laws have changed dramatically in the last five years. Here's where things stand in key markets:

California

The most ADU-friendly state in the country:

• No owner-occupancy requirement for ADUs (since 2020)
• Ministerial approval process (no discretionary review in most cases)
• No minimum lot size requirement
• One ADU + one JADU allowed per single-family lot
• Cities cannot impose parking requirements if the ADU is within half a mile of transit
• Impact fee exemptions for ADUs under 750 sq ft

Texas

• State law preempts local ADU bans in cities over 200,000 (since 2023)
• No owner-occupancy requirement in most major cities
• ADUs allowed in single-family zones in Austin, Houston, San Antonio, and Dallas
• Permitting timelines: 30-90 days typical

Florida

• Statewide ADU authorization passed in 2024
• Counties and cities must allow ADUs in single-family zones
• No minimum lot size in most jurisdictions
• Expedited permitting available

Oregon

• ADUs allowed on all residential lots statewide (since 2019)
• No owner-occupancy requirement
• System development charge waivers for ADUs under 750 sq ft
• Portland is one of the top ADU markets nationally

Washington

• State law requires cities to allow at least two ADUs per lot (since 2023)
• No owner-occupancy requirement
• Impact fee reductions for ADUs

States With More Restrictive ADU Policies

Some states still make ADU development difficult:

• Most Southeastern states: Limited statewide legislation; varies by municipality
• Midwest: Illinois, Michigan, and Ohio have no statewide ADU mandates
• Northeast: Mixed bag; Connecticut recently passed ADU-friendly legislation while other states lag

Always check your specific city and county regulations. State law sets the floor, but local zoning codes add additional requirements.

Permitting Your Garage Conversion

What You Need

1. Architectural plans. Most cities require stamped drawings from a licensed architect or designer. Cost: $2,000-$6,000.
2. Building permit. Applied for at your local building department. Cost: $500-$5,000 depending on jurisdiction.
3. Utility connections. Separate electric meter, water/sewer connections if required. Cost: $2,000-$8,000.
4. Inspections. Foundation, framing, electrical, plumbing, and final inspection. Typically included in permit fees.

Timeline

• Plan preparation: 2-4 weeks
• Permit review: 2-12 weeks (varies wildly by jurisdiction)
• Construction: 8-16 weeks
• Final inspection: 1-2 weeks

Total: 3-8 months from plans to occupancy

Permitting Pitfalls

• Setback requirements. Even in ADU-friendly states, your unit must be a minimum distance from property lines (typically 4-5 feet for detached structures).
• Height restrictions. Two-story garage conversions may be limited to 16-25 feet depending on local code.
• Utility capacity. Older neighborhoods may have limited sewer or electrical capacity. Your utility provider may require upgrades at your expense.
• HOA restrictions. Homeowners associations can still restrict ADUs in some states. California prohibits HOAs from banning ADUs, but many other states don't.

DSCR Loan Requirements for ADU Properties

Here's what lenders typically require:

• Minimum DSCR: 1.0-1.25
• Down payment: 20-25% of current appraised value (including ADU)
• Credit score: 660-700+ depending on lender
• Reserves: 3-6 months of mortgage payments
• Property type: 1-4 unit residential (the primary home + ADU usually counts as 2 units)
• ADU requirements: Must be fully permitted and have a certificate of occupancy
• Rental documentation: Signed lease or appraiser's rent estimate for both units

Key Considerations

Appraisal challenges. In markets where ADUs are newer, appraisers may struggle to find comparable sales. Work with an appraiser experienced in ADU properties. The wrong appraiser can undervalue your property by 10-20%.

Insurance. Your homeowner's or landlord insurance needs to cover the ADU. Some policies exclude detached structures or require a separate policy. Budget $300-$800/year for ADU-specific coverage.

Property taxes. Adding a permitted ADU increases your assessed value, which increases property taxes. Budget for a 15-30% increase in your annual tax bill.

Scaling: Building an ADU Portfolio

Garage conversions and ADUs aren't just one-off projects. Savvy investors are building portfolios:

The Buy-Convert-Refinance Strategy

1. Purchase a single-family home with a large garage or suitable lot for an ADU
2. Convert the garage or build an ADU ($40,000-$120,000)
3. Rent both units
4. Refinance into a DSCR loan at the new appraised value
5. Pull out equity and repeat

Example Portfolio Build

• Property 1: Purchased at $300,000. Added ADU for $65,000. Now appraised at $420,000. DSCR refinance at 75% LTV = $315,000 loan. After paying off the original purchase and conversion ($365,000), you have limited cash-out but a stabilized, cash-flowing asset.
• Property 2: Use profits and savings to repeat. Each property adds $2,000-$3,000/month in gross rental income.

After five properties with ADUs, you could be generating $120,000-$180,000 in annual gross rental income from 10 total units.

Prefab ADUs: A Faster, More Predictable Option

Prefab and modular ADUs have matured significantly:

• Companies: Abodu, Villa, Mighty Buildings, Boxabl
• Cost range: $90,000 - $180,000 installed (including site work and permitting)
• Timeline: 4-8 weeks for manufacturing, 2-4 weeks for installation
• Advantages: Fixed pricing, faster construction, consistent quality
• Disadvantages: Less design flexibility, delivery logistics, foundation still required

For investors doing multiple ADU projects, prefab units offer repeatability and predictable costs — two things that make underwriting DSCR loans much smoother.

Frequently Asked Questions

Can I get a DSCR loan just for the ADU construction?

DSCR loans are for stabilized, income-producing properties, not construction financing. Use a home equity loan, construction loan, or personal savings for the ADU build, then refinance the entire property (primary + ADU) into a DSCR loan once the ADU is rented.

Does my ADU need to be permitted to qualify for a DSCR loan?

Yes. DSCR lenders require a certificate of occupancy or equivalent documentation showing the ADU is legally permitted. Unpermitted units won't be counted by appraisers, and lenders won't include unpermitted rental income in the DSCR calculation.

What if my city doesn't allow ADUs?

Check state law first — many states have preempted local ADU bans in the last few years. If your state hasn't, you may be limited to interior conversions (like a basement apartment) or areas zoned for multi-family use. ADU legislation is expanding rapidly, so laws may change in your area soon.

How does adding an ADU affect my property's value?

Studies show permitted ADUs add 20-35% to a single-family property's value. In California, the average home value increase from adding an ADU is approximately $100,000-$200,000. The exact impact depends on ADU size, quality, local rental rates, and comparable sales.

Can I use a DSCR loan to buy a property that already has an ADU?

Yes, and this is actually the simplest scenario. The property is already producing income from both units. The appraiser documents the rents, the lender calculates the DSCR, and you close the loan. No construction risk, no permitting delays.

What's the minimum property value for a DSCR loan on an ADU property?

Most DSCR lenders have minimum loan amounts of $75,000-$150,000. Since ADU properties typically appraise at $250,000+, this isn't usually a constraint. In very low-cost markets, check with your lender on minimum loan sizes.

The Bottom Line

Garage conversions and ADUs are the lowest-barrier entry point for adding rental income to residential properties. The costs are manageable ($40,000-$120,000 for most garage conversions), the regulatory environment is increasingly favorable, and the rental income is immediate and verifiable.

DSCR loans make the long-term financing piece simple. Once your ADU is built, permitted, and rented, you can refinance based on the property's total income rather than your personal financial picture. For investors scaling a portfolio of ADU properties, this is the path of least resistance.

The key: get the permits right, budget honestly (include that 15% contingency), and confirm that your market's rents support a DSCR of 1.20 or better before you commit.

Ready to finance your ADU project? Start with HonestCasa — we'll help you figure out the DSCR math before you pick up a hammer.