How Much Does an ADU Permit Cost in LA? (2026)
ADU permit fees in LA run $4,000–$15,000 in 2026 depending on type and valuation. Garage conversions are cheapest; detached new construction is the priciest. Full breakdown by type below.
- ADU permit fees in LA run $4,000–$15,000 depending on type and valuation.
- Garage conversion: $4,000–$7,000 (cheapest, alteration permit)
- JADU: $3,000–$6,000 (interior alteration, within existing footprint)
- Attached ADU: $7,000–$12,000 (new floor area)
- Detached ADU: $9,000–$15,000+ (full new construction, longest timeline)
- Impact fees on ADUs under 750 sq ft are waived under California state law.
- Sewerage Facilities Charge (BOS) and any LADWP service upgrades are separate from LADBS permit fees.
Fee breakdown by ADU type
Garage conversion ADU ($4,000–$7,000)
Filed as an alteration. Typical $80,000 valuation:
- Building Permit (Alteration): ~$1,200
- Plan Check: ~$1,080
- Plumbing Permit: ~$300
- Electrical Permit: ~$300
- Mechanical Permit: ~$150
- Zoning Clearance: ~$200
- Sewerage Facilities Charge (BOS): ~$5,000–$8,000
- State surcharges: ~$200
JADU — junior ADU ($3,000–$6,000)
Up to 500 sq ft within the existing main-house footprint. Typical $50,000 valuation:
- Building Permit (Alteration): ~$750
- Plan Check: ~$680
- Plumbing Permit: ~$200
- Electrical Permit: ~$200
- Zoning Clearance + LAHD covenant: ~$400
- State surcharges: ~$150
Attached ADU ($7,000–$12,000)
New floor area attached to the main house. Typical $150,000 valuation:
- Building Permit: ~$2,200
- Plan Check: ~$1,980
- Plumbing Permit: ~$400
- Electrical Permit: ~$400
- Mechanical Permit: ~$200
- Zoning Clearance: ~$300
- Sewerage Facilities Charge (BOS): ~$8,000
- LAFD review: ~$150
- State surcharges: ~$300
Detached ADU — new construction ($9,000–$15,000+)
Full standalone build. Typical $200,000 valuation:
- Building Permit: ~$2,900
- Plan Check: ~$2,600
- Plumbing Permit: ~$500
- Electrical Permit: ~$500
- Mechanical Permit: ~$250
- Zoning Clearance: ~$400
- Sewerage Facilities Charge (BOS): ~$10,000
- BOE encroachment (if new driveway): ~$500
- LAFD review: ~$200
- State surcharges: ~$400
Get an exact estimate for your specific ADU.
The Permit360 fee calculator itemizes every LADBS line item against the LA fee schedule. Pair it with our ADU permit guide for the full process picture.
What drives ADU fees up or down
- Declared valuation. Permit fees are a percentage of declared project value under LAMC §98.0403.
- Size threshold (750 sq ft). Impact fees waived below 750 sq ft, proportional above.
- Lot location. Hillside zones add grading review and soils reports.
- Sewer connection availability. If BOS finds sewer capacity issues, lateral upgrade can add $5,000–$15,000.
- Electrical service. 100A panels often need upgrade to 200A before the ADU can be energized.
Hidden costs everyone forgets
- Soils report (hillside lots): $3,000–$8,000
- Architect/designer fees: 6–12% of construction cost
- Engineering stamps for structural/MEP: $1,000–$5,000
- Title 24 energy compliance documentation: $300–$800
- Sewer lateral upgrade (if BOS flags it): $5,000–$15,000
- Drainage and stormwater plan: $500–$2,000
Frequently asked questions
Are ADU permit fees waived for small units?
Yes — California state law waives impact fees for ADUs under 750 sq ft. Above 750, fees scale proportionally to the main house. LADBS building/trade permit fees still apply at all sizes.
Why are garage conversions cheaper than detached ADUs?
The garage shell already exists, so the building permit covers an alteration rather than new construction. Building permit fees are based on declared valuation, which is lower for conversions.
Does the $4,000–$15,000 include construction cost?
No. That range is permit fees only. Total ADU project cost (permit + design + construction) typically runs $80,000–$350,000 depending on type and size.
Do I pay sewer fees on top of permit fees?
Yes. The Sewerage Facilities Charge (SFC) is collected by BOS separately and runs roughly $5,000–$15,000 depending on lot location and unit count.
Can ADU fees be financed?
Permit fees are paid at the time of permit issuance, not financed. Some construction lenders roll permit fees into the overall loan; ask your lender.