ADUs · 7 min read
Building an ADU in Los Angeles: A Homeowner's Guide
What it actually takes to add an accessory dwelling unit, from feasibility to finish.
Accessory dwelling units are one of the few home projects that add living space, rental income, and resale value at once. California and Los Angeles have steadily made them easier to build, but the path still rewards homeowners who understand the variables before they start.
Start with feasibility, not design
Before spending on drawings, confirm what your lot allows: setbacks, the usable area of the rear yard, and your utility capacity. A short feasibility pass tells you whether a detached unit, an attached unit, or a garage conversion is the right path.
The three ADU paths
- Garage conversion: usually the most cost-effective, because the foundation and walls already exist.
- Attached ADU: shares a wall with the main house, often efficient for utilities.
- Detached ADU: maximum privacy and rental appeal, with the most site work.
Size and utilities
Detached ADUs are commonly allowed up to 1,200 square feet, with state rules that often guarantee at least 800 square feet. Utilities, panel capacity, sewer, and water service frequently shape both feasibility and cost more than the design does.
What drives the budget
- Whether you convert existing space or build new
- Site access and how far utilities have to run
- Finish level: rental-grade vs. owner-occupied
- Required upgrades to the main panel or sewer line
FAQ
Common questions
In most cases, yes. ADUs are widely used as long-term rentals. Local rules govern short-term rentals separately, so confirm before counting on nightly-rental income.
Plan check is typically several weeks to a few months, and construction adds several more. A garage conversion is usually faster than a new detached unit.
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