ADU Size Limits in Los Angeles: Maximum Square Footage by Zone (2026)

Planning to build an Accessory Dwelling Unit (ADU) in Los Angeles? Understanding size limits is crucial for your project’s success. California state law and Los Angeles municipal codes establish specific maximum square footage requirements that vary based on your property type, lot size, and zoning designation.

State Law Maximum ADU Sizes

California Government Code establishes baseline maximum sizes for ADUs that apply across the state:

ADU Type	Maximum Square Footage	Additional Requirements
Detached ADU (1 bedroom)	850 sq ft	No maximum height restriction beyond zoning
Detached ADU (2+ bedrooms)	1,200 sq ft	Maximum 16-18 feet height (varies by jurisdiction)
Attached ADU	50% of primary dwelling or 1,200 sq ft (whichever is less)	Must share at least one wall with primary residence
Garage Conversion ADU	No maximum (limited by existing garage footprint)	Can add up to 150 sq ft for ingress/egress
Junior ADU (JADU)	500 sq ft	Must be within existing or proposed single-family home

Los Angeles Specific Size Regulations

Los Angeles has adopted state ADU laws while adding local specifications. Here’s what you need to know:

Detached ADU Size Limits by Lot Size

Lot Size	Maximum ADU Size	Lot Coverage Limit
Less than 5,000 sq ft	800 sq ft	Cannot exceed 30% of lot
5,000 – 7,499 sq ft	1,000 sq ft	Cannot exceed 35% of lot
7,500 – 9,999 sq ft	1,200 sq ft	Cannot exceed 40% of lot
10,000+ sq ft	1,200 sq ft	Cannot exceed 45% of lot

Height Restrictions

Height limits for ADUs in Los Angeles depend on your zoning designation:

• R1 Zones (Single-Family):16 feet maximum for detached ADUs
• R2 Zones (Two-Family):18 feet maximum with flat roof; 25 feet with pitched roof
• R3/R4 Zones (Multi-Family):25 feet maximum
• Hillside Areas:Additional restrictions apply; typically limited to single-story
• Coastal Zone:May require Coastal Commission approval for structures over 18 feet

Setback Requirements That Affect Usable Space

While not technically “size” limits, setback requirements determine where on your lot you can build, which effectively impacts your ADU’s buildable area:

Setback Type	Standard Requirement	State ADU Exception
Rear Setback	15 feet (typical R1 zone)	4 feet minimum allowed
Side Setback	5 feet (typical R1 zone)	4 feet minimum allowed
Front Setback	Varies by street type (15-20 feet typical)	ADUs cannot be in front setback
Alley Setback	5 feet	0 feet allowed for ADU entrance

Special Zoning Considerations

Historic Preservation Overlay Zones (HPOZ)

Properties in HPOZ areas may face additional restrictions:

• ADU must be compatible with historic character of main house
• Size may be further restricted to minimize visual impact
• Design review required before permitting
• Materials and architectural details must match or complement existing structure

Specific Plan Areas

Certain LA neighborhoods operate under Specific Plans that may modify ADU size limits:

• Venice Coastal Zone: Additional California Coastal Commission review required
• Silverlake-Echo Park-Elysian Valley: Hillside restrictions may reduce maximum size
• Downtown LA: Different rules apply for multi-family properties
• Brentwood-Pacific Palisades: Enhanced fire safety requirements may affect design

Floor Area Ratio (FAR) Considerations

As of 2026, ADUs are exempt from FAR calculations in Los Angeles, meaning:

• Your ADU square footage does NOT count toward your lot’s maximum allowed building area
• You can build to the maximum ADU size even if your primary residence already maxes out FAR
• This exemption applies to both new construction and conversion ADUs

Multi-Family Property ADU Sizes

Apartment buildings and multi-family properties have different ADU allowances:

Property Type	ADU Allowance	Size per Unit
Multi-family (any size)	At least 2 ADUs allowed	Up to 1,200 sq ft each
Multi-family (per unit)	Up to 25% of units can be converted to ADUs	Varies by existing unit size
Commercial/Residential Mixed-Use	Detached ADU allowed	Up to 1,200 sq ft

Common Size-Related Violations to Avoid

• Exceeding Maximum Square Footage: Building larger than 1,200 sq ft without proper justification will result in permit denial
• Incorrect Lot Coverage Calculation: Must include all structures, hardscaping, and impermeable surfaces
• Height Violations: Measuring from wrong grade point or exceeding zone maximums
• Encroachment into Setbacks: Building too close to property lines without qualifying for exceptions
• Ignoring Easements: Building over utility easements (even if within your property)

How to Maximize Your ADU Size Legally

1. Accurate Lot Survey

Get a professional survey to identify:

• Exact lot dimensions and square footage
• Existing easements and setback requirements
• Optimal placement for maximum buildable area
• Topography considerations for hillside lots

2. Take Advantage of State Exemptions

• Use 4-foot setback minimums instead of local requirements
• Leverage the 150 sq ft addition allowance for garage conversions
• Don’t count ADU toward FAR limits

3. Consider a Two-Story Design

If your zone allows and you have limited lot space:

• Two-story ADUs can maximize square footage on smaller footprints
• Reduces lot coverage impact
• May provide better privacy and views
• More expensive to build but maximizes usable space

4. Combine ADU Types

California law allows you to build BOTH a JADU and a standard ADU:

• JADU: 500 sq ft inside main house
• Detached ADU: up to 1,200 sq ft in yard
• Total: 1,700 sq ft of additional living space

Pre-Approved ADU Plans and Size Standardization

Los Angeles offers a Standard Plan Program with pre-approved ADU designs in common sizes:

• 400 sq ft (studio)
• 500 sq ft (studio with separate bedroom area)
• 600 sq ft (1 bedroom)
• 800 sq ft (1-2 bedroom)
• 1,000 sq ft (2 bedroom)
• 1,200 sq ft (2 bedroom with full amenities)

Advantages of using standard plans:

• Faster permit approval (as quick as 30-60 days)
• Reduced design costs
• Pre-vetted for code compliance
• Streamlined LADBS review process

Calculating Your Maximum Allowable ADU Size

Follow these steps to determine your property’s maximum ADU size:

• Determine your lot size: Check property tax records or order a survey
• Identify your zoning: Use ZIMAS (LA’s zoning information system) at zimas.lacity.org
• Check for overlays: Look for HPOZ, Coastal Zone, Hillside, or Specific Plan designations
• Calculate lot coverage: Measure existing structures and compare to maximum allowed
• Review setbacks: Identify buildable area considering 4-foot minimum setbacks
• Apply state maximums: Use whichever is MORE restrictive between state and local limits
• Consult with professionals: An experienced ADU contractor or architect can verify calculations

2025 Updates and Changes

Recent changes affecting ADU sizes in Los Angeles:

• SB 897: Allows ADUs up to 1,200 sq ft regardless of lot size (previously more restricted)
• Streamlined Approvals: ADUs meeting size requirements get ministerial approval (no discretionary review)
• Fire Sprinkler Exemptions: ADUs under 1,200 sq ft typically don’t require sprinklers
• Impact Fee Waivers: ADUs under 750 sq ft exempt from impact fees in LA

When You Might Need a Variance

In rare cases, you may need to request a variance for size-related issues:

• Irregular or extremely constrained lot configuration
• Pre-existing non-conforming structures limiting buildable area
• Unusual easement situations
• Extreme topography (steep hillside lots)

Note: As of 2026, variances for ADUs are generally NOT required for size if you’re within state maximums, even if local codes are more restrictive.

Key Takeaways

• Maximum detached ADU size in LA is 1,200 sq ft (state law)
• Lot coverage limits may restrict ADU size on smaller lots
• Height limits vary by zone: 16-25 feet typical
• ADUs are exempt from FAR calculations
• Setbacks can be as small as 4 feet for ADUs
• Pre-approved plans available in standard sizes up to 1,200 sq ft
• You can build both a JADU (500 sq ft) and full ADU (1,200 sq ft) on same property
• Special overlay zones may have additional restrictions

Understanding these size limits is the first step in planning your ADU project. For a comprehensive analysis of your specific property’s potential, consult with an experienced ADU contractor who understands both state law and Los Angeles municipal requirements.