ADU 101 — How to Add a Unit and Collect Rent
ADU Strategy Breakdown for Military Homeowners

California passed some of the most ADU-friendly laws in the country between 2020 and 2023. If you own a home in San Diego — or are buying one — you likely have the right to add a separate dwelling unit on your property and rent it out for income. For military homeowners, this changes the entire math of ownership.

What Is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary residential unit on a single-family or multi-family lot. It's a complete, self-contained dwelling with its own entrance, kitchen, bathroom, and sleeping area — separate from the primary home. ADUs go by many names: granny flats, in-law units, casitas, backyard cottages, or secondary suites.

The defining characteristic is that an ADU can be independently rented to a tenant who is not a family member — making it a legal income-producing asset attached to your property.

What California's ADU Laws Changed

Before 2020, ADUs were theoretically legal in California but practically difficult to build. Local zoning restrictions, design review requirements, excessive fees, and parking requirements made the process slow, expensive, and uncertain.

California's ADU reform legislation — AB 68, AB 881, AB 3182, and subsequent bills — eliminated most of these barriers:

• No more parking requirements for ADUs within half a mile of transit (which covers most of San Diego)
• By-right approval — no discretionary design review for compliant ADUs
• Impact fee caps — fees dramatically reduced for ADUs under 750 sq ft
• Streamlined permitting — 60-day approval requirement for qualifying ADUs
• Setback reductions — most ADUs can be built 4 feet from rear and side property lines
• Owner-occupancy requirements eliminated — you don't need to live on the property to build or rent an ADU

Types of ADUs — Which Makes Sense for Your Property

For most military homeowners in San Diego, a garage conversion or prefab detached ADU offers the best combination of cost, speed, and rental income potential. The garage conversion path is particularly powerful: you're converting a non-income-producing space into a unit that rents for $1,800–$2,400/month.

ADU Costs in San Diego — Real Numbers

ADU costs in San Diego are higher than California averages due to labor costs, permit fees, and soil/grading requirements on many lots. Here's a realistic breakdown for a 400–600 sq ft detached ADU:

Garage conversions reduce this significantly: no foundation, no framing from scratch, existing utilities already run to the structure. A quality garage conversion to a 1BR/1BA ADU in San Diego can be completed for $90,000–$140,000.

Rental Income Potential in San Diego

San Diego's rental market is among the tightest in California. Military-adjacent neighborhoods benefit from persistent demand: service members who can't or choose not to buy, contractors, and military families waiting for housing.

At $2,000/month, an ADU generates $24,000/year in gross rental income. At a conservative 6% cap rate, that income stream represents $400,000 in added property value. The ADU doesn't just produce monthly cash flow — it materially increases what your property is worth.

How to Finance ADU Construction

VA loans don't directly fund ADU construction on an existing property, but there are several viable paths:

• VA Cash-Out Refinance: If you have equity in your home, a VA cash-out refi can pull funds to finance construction. VA allows up to 100% of appraised value in most cases.
• Home Equity Line of Credit (HELOC): If you have a low-rate VA mortgage you don't want to refinance, a HELOC at a second-lien position can fund construction without touching your first mortgage.
• Construction-to-permanent loan: A construction loan funds the build, then converts to a permanent mortgage upon completion. Can sometimes be refinanced to a VA loan afterward.
• California ADU financing programs: CalHFA and some local programs offer ADU-specific financing. CalHFA's ADU Grant program has provided up to $40,000 in no-repayment grants to qualifying homeowners.

The Military Homeowner ADU Strategy

Here's the full picture for a military buyer who plays this right:

1. Buy a home with VA loan — ideally a property with ADU potential (large lot, detached garage, or existing unfinished space)
2. Live in the property while stationed at the base — collect zero rent initially, build equity
3. Before your next PCS, build or convert the ADU using home equity
4. Upon PCS: rent the primary home for $2,500–$3,500/month and the ADU for $1,800–$2,200/month
5. Gross monthly rental income: $4,300–$5,700 — well above a typical PITI on a $600K–$700K San Diego purchase
6. Property cash-flows positive from day one of your next duty station

This is not speculative. This is the actual outcome for military homeowners who bought in San Diego 3–5 years ago, built ADUs, and PCS'd out. The combination of VA loan zero-down purchase, California's rental market strength, and ADU income creates a wealth-building machine that compounds across multiple duty stations.