San Diego Duplex & Multifamily Buyer's Guide
Everything a first-time multifamily buyer needs to know about buying a 2-4 unit property in San Diego — what to buy, how to finance it, what the numbers look like, and how to avoid the mistakes that cost people in this market.
Why buy multifamily in San Diego?
San Diego is one of the most expensive real estate markets in the United States. But for a coastal California market, there is still a lot of value to be had, and the long-term economics continue to make it a compelling place to buy and hold.
Whether you are purchasing a property to house hack — owner-occupying one unit and renting the others — or buying as a pure investment, the fundamentals here are strong. Average rents are high, vacancy is low, and demand is not going away.
Low vacancy means units rarely sit empty. That rental income is real, durable, and becomes more valuable over time as rents rise. For long-term hold investors, San Diego has consistently rewarded patience.
Duplex vs triplex vs fourplex: what's the difference?
The type of property you buy changes your financing options, your income potential, and your management responsibility. Here is a quick breakdown:
| Property type | Units | Financing | Best for |
|---|---|---|---|
| Duplex | 2 | Residential | First-time house hackers; simplest entry point |
| Triplex | 3 | Residential | More income, still residential financing |
| Fourplex | 4 | Residential | Maximum income, still owner-occupied eligible |
| House + ADU | 1+1 | Residential | Privacy of a single family home with ADU rental income |
| 5+ units | 5+ | Commercial financing | Portfolio investors only; different rules entirely |
Important: A house with an ADU and a true duplex are not treated identically by lenders. Loan limits and financing terms can differ between the two, so it is worth understanding which type of property you are looking at before you get pre-approved. Ask your lender upfront how they treat each.
House hacking in San Diego: what it actually looks like
House hacking means buying a multifamily property, living in one unit, and renting the others. The rent from your tenants offsets a significant portion of your mortgage payment every month.
In San Diego, especially when purchasing with a low down payment, the other units will not always cover your entire mortgage from day one. But over time, as rents increase, that gap closes. And when you have the opportunity to refinance at a lower rate, it is not uncommon to reach a point where the rental income from the other units covers your entire mortgage while you live in your unit for practically nothing.
Example: You buy a triplex and owner-occupy one unit. The two rental units each bring in $2,400 a month. That is $4,800 per month working against your mortgage. Depending on your purchase price and loan terms, that could cover 50% or more of your total housing payment from day one, with the potential to cover all of it as rents grow over time.
Live in one unit
You qualify for owner-occupied financing with lower rates and a lower down payment.
Rent the others
Tenant rent covers a significant portion of your mortgage from day one.
Build equity
Appreciation and loan paydown grow your net worth while you live there.
Move out later
Rent your unit too when you move. Now it is a fully operating investment property.
How to finance a 2-4 unit property in San Diego
Because 2-4 unit properties are still classified as residential real estate, buyers have access to the same loan programs available for single-family homes. The financing options are more flexible than most people expect.
FHA loan
3.5% down. Must owner-occupy one unit. Lenders can count projected rental income to help you qualify. Best for first-time buyers with limited capital.
Conventional loan
5% down for owner-occupied 2-4 units. No mortgage insurance at 20% down. Good for buyers with solid credit and income.
VA loan
0% down for eligible veterans and active duty. One of the most powerful financing tools available, especially applied to a 2-4 unit property.
Investment (non-owner)
Purchasing as a pure investment without living there typically requires 25% down on a 2-4 unit property.
Rental income credit: Most lenders will count 75% of projected market rents from the units you will not occupy toward your qualifying income. This is one of the biggest advantages of buying 2-4 units and helps many buyers qualify who could not on a single-family home alone.
What to look for in a multifamily deal
Not every multifamily property is a good investment. Here is what to analyze before you make an offer:
Gross rent multiplier (GRM)
GRM is calculated by dividing the purchase price by the annual gross rents. It gives you a quick way to compare properties and understand how much you are paying relative to the income a property produces.
Current rents vs market rents
Are current rents at market or below? Below-market rents represent upside. Know what comparable units are actually renting for before you make an offer, not just what the seller tells you.
Unit mix and condition
How many beds and baths per unit? Larger units command higher rents. Factor in deferred maintenance and repair costs before you determine your offer price.
ADU potential
Can you add an ADU? California's ADU laws are among the most flexible in the country. An additional unit can meaningfully increase both monthly income and long-term property value.
Tenant situation and rent control
Understand who is currently in the property and what they are paying. AB 1482 rent control applies in California, so know your ability to adjust rents before you underwrite the deal.
The multifamily buying process, step by step
Get pre-approved with a multifamily-savvy lender
Not all lenders understand how rental income offsets your debt-to-income ratio. Work with one who does from day one. It changes what you can qualify for.
Define your criteria
What neighborhoods? What price range? Are you house hacking or buying as a pure investment? These answers shape your search and keep you focused.
Analyze properties before you tour them
Run the numbers on every property before you walk in the door. Emotional decisions on multifamily cost people money. Know your maximum offer before you see it in person.
Make a competitive offer
Good multifamily in San Diego moves fast. Know your numbers so you can move decisively when the right property appears.
Due diligence
Inspect everything. Review leases, estoppel certificates, rental history, utilities breakdown, and any permits — especially for ADUs.
Close and take over
Introduce yourself to tenants, collect security deposits, and confirm lease terms. You are now a landlord in one of the strongest rental markets in the country.
Common mistakes first-time multifamily buyers make
Common questions about buying multifamily in San Diego
Ready to find your San Diego multifamily property?
I specialize in 2-4 unit properties and ADUs across San Diego. Let's talk through what you are looking for and whether the numbers make sense for your situation.