How to get an ADU permit in Los Angeles (the full step-by-step)

The LA ADU permit process has seven distinct phases. Most homeowners don't realize this until they're already in phase 3 and confused about why phase 4 won't let them proceed. Here's the full walkthrough.

Quick answer

The LA Accessory Dwelling Unit (ADU) permit process runs through seven phases over roughly 8 to 15 months. For a typical 500 sqft detached ADU built from a Permit Ready ADU (PRADU, also called a pre-approved standard plan), the realistic all-in total is $145,000 to $225,000.

Phase	Time	Cost
1. Feasibility check	1-2 days	$0
2. Plan selection (YOU-ADU, PRADU, or custom)	1-4 weeks	$0 to $25K
3. Site-specific prep (survey, site plan, disclosures)	2-4 weeks	$2K to $6K
4. LADBS plan check (corrections iteration)	5 days to 6 months	$3K to $10K
5. Permit issuance (final fees and pickup)	1-3 days	$4.5K to $9.5K+
6. Construction with 10 milestone inspections	3 to 12 months	varies by build
7. Certificate of Occupancy (CofO)	1-2 weeks	$0 to $200

Phase 1 is free and tells you whether your lot can support an ADU before you spend a dollar elsewhere. Run your address through the wizard to do that step now.

Phase 1: Feasibility check (1-2 days, free)

Before spending any money, confirm your property can support an ADU. The five eligibility factors (jurisdiction, zoning, overlays, lot size, deed restrictions) are covered in our eligibility guide. The fastest way to run all of them is our wizard which checks LADBS data + 14 NavigateLA layers + LA County Assessor data automatically against your address.

What you walk away with: a verdict (likely yes / uncertain / out-of-area), a list of overlays applicable to your lot, your zoning code, and an approximate cost range.

Cost: $0. Don't pay anyone to check feasibility. The free tools exist.

Phase 2: Plan selection (1-4 weeks, $0 to $25,000)

Three options for how you get plans for your ADU:

1. YOU-ADU: City of LA's free 455 sqft pre-approved plan. Detached, 1 bed / 1 bath, three style options (White, Charcoal, Spanish, Craftsman). Genuinely free. Best for budget-focused homeowners.

2. LADBS pre-approved designer plan (a "PRADU"): license one of 80+ designer-firm plans (ADU1 through ADU96) for $2,000 to $8,000. Browse them at /standard-plans. Faster plan check than custom (often 5 days vs. 60+) because the design is already approved.

3. Custom architect-drawn plan: hire an architect for fully bespoke design. $5,000 to $25,000 for the design package. Slowest plan check (60+ days, often 90-120 days in 2025-2026 real-world practice).

HCD-approved prefab path: separate from the three above. Companies like Connect Homes and Cover ship factory-built ADUs that skip LADBS plan check entirely because the unit is factory-certified to California Department of Housing and Community Development (HCD) standards. Only site work gets permitted. Cost: $190K-$350K turnkey.

What you walk away with: a permit-ready plan set or a contract with a designer who'll produce one.

Phase 3: Site-specific preparation (2-4 weeks, $2,000 to $6,000)

Before LADBS will accept your plan set, you need site-specific information added:

• Property survey (if you don't have a current one): $1,500-$3,000. Confirms setbacks, lot dimensions, and existing structures.
• Site plan: shows where the ADU sits on your lot, setbacks, utility runs.
• Title sheet: cover page with property info, zoning, applicable overlays, scope of work.
• Disclosure forms: hillside grading disclosures, fire-hazard zone acknowledgments, scenic-overlay forms, etc., depending on your property's overlays.

If you went the YOU-ADU or PRADU route, your plan firm typically handles this for a small additional fee ($300-$1,000). For custom plans, your architect packages it.

The PermitPathLA wizard's prep-submittal step walks through the title sheet contents and overlay disclosures for your specific lot.

Phase 4: LADBS plan check (5 days to 6 months, $3,000 to $10,000)

You submit your plans to LADBS through their PermitLA system (online portal) or in-person at the Bay Counter. Submittal fees:

• Building permit (covers plan check): roughly 65% of the eventual building permit fee, paid upfront
• Plumbing, electrical, mechanical sub-permits: $500-$1,500 each
• State and city surcharges: $200-$500

Plan check timeline by path:

• HCD prefab (Connect Homes, Cover): minimal LADBS plan check, often 5-15 days for site work
• PRADU (pre-approved designer plan): 5 days same-day-issuance (theoretical), 2-4 weeks practical
• YOU-ADU (City of LA free plan): same-day to 5 days theoretical, 1-3 weeks practical
• Custom architect plan: 60-day LADBS target, 90-120 days realistic, 6+ months for hillside or HPOZ properties

During plan check, LADBS issues "corrections", items that need to be fixed before approval. Most projects get 1-3 rounds of corrections. Each round takes 1-3 weeks for your designer/architect to respond. Our LADBS plan-check pipeline guide breaks down what each plan checker is looking for.

What you walk away with: approved plans, plan check complete, ready to pay final fees and pick up the building permit.

Phase 5: Permit issuance (1-3 days, $4,500 to $9,500+)

Once plan check is approved, LADBS calculates final building permit fees and any additional surcharges. You pay them and the building permit issues.

Standard LA permit fees for a typical 500 sqft detached ADU:

• Building permit: $4,500-$9,500 (varies by valuation)
• Plumbing, electrical, mechanical: already paid at submittal
• State and city surcharges: $200-$500
• Records management + technology fees: $100-$300
• For ADUs over 750 sqft: LAUSD school impact fee at $4.79/sqft + LA residential development impact fee
• For grading work (hillside): separate grading permit, $1,500-$4,000

You can pull the permit online via PermitLA or in-person.

What you walk away with: physical building permit posted at the job site, ready to start construction.

Phase 6: Construction with inspections (3 to 12 months, varies)

You can't just build the ADU and call it done. LADBS requires inspections at specific construction milestones:

1. Foundation inspection: after concrete forms are set, before pour
2. Underground plumbing: before backfill
3. Underground electrical: before backfill
4. Framing/sheathing: after framing, before drywall
5. Rough electrical: after wiring, before drywall
6. Rough plumbing: after pipes, before drywall
7. Rough mechanical (HVAC): after ductwork, before drywall
8. Insulation: after insulation install, before drywall
9. Drywall (some districts): after install, before tape
10. Final inspection: after everything else, before certificate of occupancy

Each inspection: schedule via PermitLA, inspector visits in 1-5 business days, passes or issues correction notice.

Total construction timeline:

• Garage conversion: 3-6 months from permit to final
• Detached new construction: 6-12 months
• Hillside or complex: 10-18 months

This is also when you discover whether your contractor knows what they're doing. If they're failing inspections repeatedly, you're paying for rework and your timeline blows up. CSLB license verification (at cslb.ca.gov) before signing a contract is critical.

Phase 7: Certificate of Occupancy (CofO) (1-2 weeks, $0 to $200)

After passing final inspection, LADBS issues a Certificate of Occupancy. This is the legal document that says the ADU can be occupied as a dwelling.

You need the CofO to:

• Insure the ADU
• Rent the ADU legally
• Refinance with the ADU's value counted toward your loan amount
• Sell with the ADU disclosed correctly

Without a CofO, the ADU technically exists but legally doesn't. You really, really want this document.

Total realistic timeline and cost

For a typical 500 sqft new-construction ADU in LA, using a pre-approved designer plan (PRADU):

Phase	Time	Cost
Feasibility check	1-2 days	$0
Plan selection (PRADU license)	2-4 weeks	$2K-$8K
Site-specific prep	2-4 weeks	$2K-$6K
LADBS plan check	2-4 weeks	$5K-$10K
Permit issuance	1-3 days	$5K-$10K
Construction + inspections	6-12 months	$130K-$190K
Certificate of Occupancy	1-2 weeks	$0-$200
Total	8-15 months	$145K-$225K

A custom-designed ADU on a hillside lot can easily run 18-24 months and $300K+ for the same square footage. The wizard's cost calculator prices your specific lot.

What to actually do next

1. Run your address through the wizard for the feasibility check and overlay summary.
2. If the verdict is "likely yes," compare PRADU plans at /standard-plans against your lot's constraints.
3. If you'd prefer a contractor handle everything, browse vetted LA design-build firms at /contractors.
4. If you want pricing for your specific lot before contacting anyone, use the cost calculator.

The seven phases above are universal. Your specific path through them depends on lot, budget, and timeline preferences.