Detached ADU with modern design
Detached ADU with modern design
Cost Guide

ADU Construction Cost in San Diego: Real Numbers for 2026

ADU Construction costs in San Diego, with budget ranges, permits, timeline, and contractor guidance from Cali Dream Construction. Our team serves homeowners throughout La Jolla and greater San Diego County.

Cost Snapshot

Budget project$150,000 to $240,000
Mid-range project$240,000 to $400,000
High-end project$400,000 to $650,000+
Typical planning contingency10% to 15%
Permit and plan review allowance1% to 4% of construction value when permits apply

Final cost depends on drawings, finish selections, utility work, structural changes, and permit scope. Use this as a planning range before a site-specific estimate.

What Drives Cost In San Diego

  • Detached ADUs cost more than many garage conversions because they need foundation, envelope, and utility work.
  • Sewer, electrical panel, trenching, and fire separation can change the budget materially.
  • Plan review, coastal overlays, and site access affect timeline and carry cost.
  • Rental-ready finishes, durable flooring, and storage add long-term value.

How To Keep The Budget From Drifting

Lock selections early, separate must-have scope from optional upgrades, and review allowances before signing. The biggest overruns usually come from vague finish allowances, structural surprises, and permit-driven plan changes.

Cali Dream Construction prices these conversations around real scope so a homeowner can compare options without bait-and-switch numbers.