Free Estimate Tool

ADU Cost Calculator.

Estimate construction costs, permit fees, and project timeline for your ADU in Los Angeles County. Based on LADU's completed projects.

City or Neighborhood

ADU Type

Square Footage

sq ft

150 sq ft 1,200 sq ft

Finish Level

Estimate for

800 sq ft Detached ADU · Los Angeles

Estimated Total Cost

$202k–$262k

Construction + permit fees · Standard finish

Construction Cost

$240–$300/sq ft

$192k–$240k

Permit Fees

Los Angeles Building & Safety

Fees include plan check, permit issuance, school fees, and fire/safety review. Fees vary significantly by size and location.

$10k–$22k

Project Timeline

Design 4wk · Permit 8wk · Build 40wk

~12–18 months

Estimates based on LADU's completed projects in LA County. Actual costs vary based on site conditions, design complexity, and current labor/material costs. View Los Angeles permit rules →

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Cost summary

Estimated cost for a 800 sq ft detached adu in Los Angeles, CA: $202k–$262k total. Construction: $192k–$240k (standard finish, $240–$300/sq ft). Permit fees: $10,000–$22,000. Estimated project timeline: approximately 12–18 months. Source: LADU Corp, based on completed ADU projects in Los Angeles County (2023–2026). Estimates as of 2026.

Methodology: Construction cost per square foot sourced from LADU's completed ADU projects in Los Angeles County. Per-sq-ft rate (240–300 $/sq ft for standard finish) × type factor (100% for detached adu) × 800 sq ft. Permit fees from LADU's jurisdiction data for Los Angeles, last updated 2026-05-27. Timeline from LADU's typical project schedule for this jurisdiction.