ADU Plans in Los Angeles

The Three Types of ADU Plans

Every ADU built in LA traces back to one of three plan types. Picking the right one for your situation is the single biggest decision you make in the permit process.

1. Custom ADU plans

Drawn from scratch for your specific lot, family, and design preferences. Best if your lot has unusual constraints (slope, irregular shape, hillside, easements), or if you have a specific architectural vision. Slower (8-14 weeks) and more expensive ($6,000-$22,000), but the only path that gives you full control over the result.

2. Pre-approved ADU plans (AB 1332)

Stock designs that have already been approved by your local building department. Skipping plan check entirely. A growing number of California cities have pre-approved plan programs after AB 1332 took effect. In LADBS, the program covers a range of 1-bedroom, 2-bedroom, and studio designs at various footprints. Permits issue in roughly 30 days. Fastest path; lowest plan cost ($1,500-$4,500). Trade-off: limited to the available designs.

3. Modified stock plans

Start with a pre-approved plan and modify it to fit your lot or layout preferences. Keeps most of the speed advantage of pre-approved plans, but loses the automatic plan-check bypass for the modified portions. Best when a stock plan is 80% right but needs a layout tweak or footprint adjustment.

What’s Actually In an ADU Plan Set

A complete LA ADU plan set is typically 15 to 30 sheets. Here is what each section covers and why it exists:

How ADU Plans and Permits Connect

The phrase “ADU plans permits” gets used loosely. Strictly speaking, plans and permits are two different deliverables:

• ADU plans are the architectural and engineering drawings.
• ADU permits are the legal authorizations from the building department that allow construction to begin.

The relationship: you cannot get permits without plans. The building department reviews the plans, and the issued permit is essentially the city’s signed-off copy. CCS produces both as one workflow: drafting, plan check, permit issuance, and construction-phase support, all under one contract. See our ADU Permit service for the full permit workflow.

What ADU Plans Cost in LA (2026)

For an 800-1,200 sq ft detached ADU:

• Pre-approved plans (AB 1332): $1,500-$4,500 for the plan set itself. Adoption fees vary by city.
• Modified stock plans: $3,500-$7,500.
• Fully custom plans: $6,000-$22,000 depending on lot complexity and designer.
• Hillside or constrained lots: add $2,500-$8,000 for geotech coordination, retaining wall design, and drainage engineering.

These are plan-set fees only. Permit fees paid to the city are separate. See the full ADU permit cost breakdown by LA city.

Pre-Approved ADU Plans in LA

Pre-approved ADU plan programs are the single biggest permit accelerator. The LA City pre-approved plan program covers a catalog of designs from approved providers, ranging from 400 sq ft studios up to 1,200 sq ft 2-bedrooms, in modern, traditional, and contemporary styles. When you submit a pre-approved design without modification, plan check is largely bypassed and permits issue in roughly 30 days.

The LA City program is voluntary and growing. See our complete guide to pre-approved ADU plans in LA for the participating cities, the available design catalogs, and how to enroll.

See Your Plan Options

Tell us your address and what you want to build. We will tell you which plan path (custom, pre-approved, or modified stock) is fastest and cheapest for your specific lot, and the realistic timeline and cost. Free, no obligation. Call (323) 405-8909 or schedule a free consultation.