The value question that deserves a real answer
Homeowners considering a garage conversion in San Diego consistently ask two things: how much will it cost, and will it increase my home’s value by at least that much? The second question is harder to answer honestly because it depends on how the conversion is done, how it is permitted, and what the local market is doing.
The short answer: a permitted garage-to-ADU conversion in San Diego almost always adds value, typically more than its cost on a dollar-for-dollar basis in a market with strong rental demand and high home prices. An unpermitted conversion almost never adds full value and often creates liability that reduces what buyers will pay.
The longer answer requires understanding how appraisers treat ADUs.
How appraisers value garage conversions
In California real estate, appraisers use the sales comparison approach to estimate value. They find comparable sales (comps) of properties with similar improvements and apply those comparisons to your home. The challenge with ADUs and garage conversions is that comps for ADU-equipped properties have become more common but are still not uniformly available in all San Diego neighborhoods.
For a permitted garage ADU conversion, appraisers generally account for the additional square footage of habitable space, the income-generating potential of the unit (using an income approach or gross rent multiplier), and comparable sales of similar ADU properties in the area.
In practice, San Diego appraisers in submarkets with active ADU activity (North Park, City Heights, Normal Heights, South Park, Barrio Logan, Chula Vista, Logan Heights) are more likely to find relevant comps and apply them accurately. In lower-density east county or north county coastal markets where ADU comps are sparse, appraisers may add less value per dollar of conversion cost.
A rough benchmark from San Diego area real estate experience: a permitted ADU conversion typically returns $0.80-$1.20 in appraised value per dollar of conversion cost in submarkets with strong rental demand. In markets with fewer ADU comps, the return may be closer to $0.60-$0.80.
The rental income multiplier
One significant factor in how appraisers and buyers evaluate ADU-equipped properties is rental income potential. An ADU that can generate $1,800-$2,200 per month in rent adds a visible financial argument for the premium price.
Buyers who are investors or owner-occupants comfortable with landlord responsibilities will pay more for a property that already has a cash-flowing ADU. In San Diego’s housing market, that buyer pool is substantial. Properties marketed as “ADU included, currently renting for $X/month” command premiums that can outpace the conversion cost, particularly in neighborhoods close to SDSU, UCSD, downtown, or Chula Vista’s growing rental market.
The income approach is most powerful when the ADU is already rented and has a track record. An unrented but permitted ADU adds value, just with more buyer estimation involved.
The garage loss: what buyers think
A real concern, and one worth addressing directly: some buyers specifically want a garage. In San Diego, where street parking is competitive in many neighborhoods and where cars are essential, a property with no garage is worth less to some buyer segments than a property with one.
This is real but contextual. In dense urban neighborhoods like North Park, South Park, or University Heights, buyers have already priced in limited parking and the garage loss is often not a significant discount. In suburban neighborhoods like Rancho Bernardo, Scripps Ranch, or Eastlake where most comparable homes have garages and street parking is ample, the missing garage may produce a more noticeable discount.
The net result for most San Diego conversion projects: the value added by a rental ADU exceeds the value lost by converting the garage, particularly in urban and transit-adjacent neighborhoods. In lower-density suburban markets, the calculation is closer and depends more heavily on the quality of the conversion and the strength of the ADU income story.
Permitted versus unpermitted: the value gap
An unpermitted garage conversion is a different calculation entirely. It adds square footage that cannot be counted in the appraisal, creates disclosure liability for the seller, and frequently requires the buyer to either negotiate a price reduction or plan for the cost of legalization.
The cost to retroactively permit a garage conversion in San Diego often runs $10,000-$30,000 or more after factoring in plan preparation, permit fees, corrections required by the inspector, and any remediation work needed to bring the conversion up to current code. Buyers who understand this will discount accordingly.
An unpermitted conversion done years ago by a previous owner is a common find in San Diego’s older housing stock in Normal Heights, North Park, City Heights, and other neighborhoods built in the 1940s-1960s with detached garages. If you are buying a home with an unpermitted conversion, get a clear-eyed estimate of legalization costs before closing.
What increases the value of a conversion
Conversions that add the most value in San Diego share common characteristics:
Separate exterior entrance with good privacy from the main home. Tenants pay more for a unit that feels like its own place, not an addition to someone else’s house.
A full bathroom and a real kitchen (not just an efficiency setup). Units with both command meaningfully higher rents and broader buyer appeal.
Good natural light. Converting a garage door opening to windows and a glass-panel door transforms the feel of the space. A windowless conversion feels like a storage unit.
Mini-split HVAC that keeps the space comfortable year-round. San Diego’s climate is mild, but a unit without cooling or heating will sit vacant in summer or winter.
Good soundproofing between the unit and the main house, particularly for attached garages where noise travels through shared walls.
To get connected with experienced, insured contractors who specialize in high-quality garage conversions across San Diego County, visit the garage conversion service page or call (858) 925-5546.
Does converting a garage to an ADU increase property taxes in San Diego?
Yes. A permitted ADU conversion increases the assessed value of the property, which increases property taxes. The increase is based on the added improvement value, not a full reassessment of the entire property under Proposition 13.
Will I lose value by not having a garage?
It depends on the neighborhood. In dense urban San Diego neighborhoods, the loss of a garage has minimal impact on value because comparable homes also lack garages. In suburban neighborhoods where garages are standard, there may be a measurable discount, but it is typically offset by the ADU income potential.
How do I find comps for ADU properties near me?
A local real estate agent with ADU experience in your neighborhood is the best source. Alternatively, a licensed appraiser can run a specific comp search. County assessor records at sdarcc.gov show permit history and square footage for recorded improvements.
Does a JADU add as much value as a full ADU?
Generally less. A JADU is limited to 500 square feet, rents for less than a full ADU, and may require the owner to remain on the property (depending on current state law). A full ADU’s rental income potential typically produces a larger value premium, though at higher conversion cost.
Learn more about what a full conversion involves on our full ADU conversion service page.