Mistakes LA homeowners make with their first ADU

Setback geometry, easements, and the actual location of underground utilities determine where your ADU can physically go. Pricing a 'standard 750 sqft detached ADU' before a current existing-conditions survey is the single most common source of mid-project surprises.

Pull a current ALTA or boundary survey before you commit to a budget. The American Land Title Association's standards are the spec ALTA — survey standards.

Panel upgrades, sewer lateral repairs, water meter sizing — none of these show up in standard $/sqft pricing. ENERGY STAR's heat pump installation guidance ENERGY STAR heat pump guidance gives a sense of the new electrical loads ADUs put on existing services. The LADBS fee schedule LADBS permit fee schedule covers the City side; LADWP and LA Sanitation have their own.

Reserve $15,000–$35,000 for utility work on most LA ADU projects. Hillside lots can run higher.

On any LA lot with slope, fill, expansive clay, or proximity to a fault zone, a geotech is non-negotiable. Even on flatter lots, a $2,500 geotech can prevent a $40,000 foundation surprise. SEAOC's design standards explain why SEAOC structural design standards and the California Geological Survey publishes the hazard maps California Geological Survey hazard maps.

Whether your project is purely ministerial, requires a CDP, or triggers HPOZ review changes the design choices dramatically. Confirm the permit pathway before the architect bills for design hours. HCD's ADU memos California HCD ADU memos and LA Planning's preservation guidance LA Planning historic preservation guidance are the right starting points.

Most construction loan rate locks are 60–90 days. LA ADU permit timelines run 12–18 weeks for clean projects and longer for anything in Coastal or HPOZ. Locking too early means you'll relock at whatever the market gives you in month 4. The Mortgage Bankers Association tracks the rate environment MBA — rate environment research and Bankrate is good for current product comparisons Bankrate — construction loan products.

6) Choosing a contractor without verifying the CSLB license — it's a 30-second check at the Contractors State License Board California Contractors State License Board. 7) Not pulling permit history on the existing main house. 8) Ignoring tree-protection ordinances during site planning. 9) Specifying gas appliances when Title 24 favors all-electric. 10) Failing to plan landscaping and irrigation before the permit is closed. 11) Treating change orders as 'small' — they compound. 12) Hiring an architect with no LA ADU permits in their last 12 months of work.

The LA Times has covered owner mistakes on local projects in detail and Curbed LA tracks the recurring patterns by neighborhood — both worth reading before you commit.