Room Addition vs. ADU: Which Way Should Your LA Home Grow?

When an LA family outgrows its house, moving means giving up a low property-tax basis and a neighborhood you love. Adding square footage is usually the smarter math — and California's ADU-friendly laws have created three distinct paths. Here's how to choose.

Path 1: The attached room addition

$350–$650 per square foot in the LA market — a typical 300–500 sq ft addition lands between $120,000 and $300,000. You get space that flows with the house: a primary suite, a bigger kitchen and family room, a home office. Foundation, framing, roof tie-in, HVAC extension and full finish, engineered and permitted.

Choose this when: the goal is more living space for your own family, and the yard has room to give.

Path 2: The garage conversion ADU

$90,000–$150,000 — the budget door into ADUs, because the structure, slab and roof already exist. Insulation, kitchen, bathroom, separate entry, and it becomes a permitted dwelling. California law has made these dramatically easier to approve, and parking replacement is generally not required.

Choose this when: you want rental income or family housing at the lowest entry cost — and you can live without the garage.

Path 3: The detached ADU

$180,000–$350,000 for a ground-up backyard unit. Its own foundation, utilities, kitchen and bath — a real second home on your lot. As a long-term rental in LA, the income stream is substantial; as multigenerational housing, it buys privacy an addition can't.

Choose this when: the lot is big enough, and the goal is income or independent living rather than more space for the main house.

The permit reality

Additions go through standard plan check; ADUs ride a state-streamlined process most LA-area cities must approve within set timelines. Either way you need engineering, Title 24 energy compliance, and a contractor who has run the gauntlet before. We handle drawings, calcs and the process end to end — it's half the job.

The value math

Added square footage appraises; permitted ADUs appraise and produce income. What doesn't appraise: unpermitted conversions — they subtract value and complicate every future sale. Whatever path you pick, do it on the record.

Tell us your lot, your goal and your budget — we'll tell you which of the three paths fits, with real numbers for your property.