What really drives the cost of an ADU in Los Angeles
Two ADUs of the same size can have very different budgets. The difference rarely comes from the finishes alone: it comes from the lot. Understanding the six main cost drivers helps you compare quotes and avoid surprises.
1. Size and layout
Square footage matters, but so do the number of rooms, bathrooms and the complexity of the plan. A simple rectangle is more efficient to build than a plan with many corners.
2. ADU type
A garage conversion reuses an existing structure; a detached ADU starts from a new foundation; a second-story unit requires structural work on the building below. Each carries a different scope.
3. Site access
A wide side yard lets crews and materials reach the build area easily. A tight access may mean smaller equipment, more labor or special deliveries.
4. Utilities
The distance to water, sewer, gas and electrical connections, and their capacity, can change the budget significantly. An electrical panel upgrade is a common example.
5. Foundation and structure
Soil, slope and the condition of any existing slab or walls decide the foundation and structural work.
6. Finishes
Cabinetry, flooring, fixtures and appliances range from essential to premium. This is where you have the most control.
We give you a realistic estimate after the free visit, and the firm price is written into your contract before construction starts. Use our free cost planning worksheet to prepare that conversation.
Remember to keep a contingency for unforeseen site conditions, and to ask any builder exactly what a quote includes: design, engineering, permits, city fees, utilities and finishes.
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