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RSA Development · The Reference DeskLos Angeles · 22 entries · rev. 2026-09-26

A field reference for owners considering an ADU in Los Angeles.

Frequently
questioned.

"The honest answer to a hard question is worth more than ten brochures."

— house motto

22 answers across 5 chapters

Filter

Most-asked · readers' choice

I

Chapter I · 4 entries · reviewed

Time & sequence.

How long things actually take in Los Angeles — from first phone call to certificate of occupancy.

II

Chapter II · 4 entries · reviewed

Cost & scope.

How to organize an ADU budget around the property, scope and unresolved conditions.

III

Chapter III · 5 entries · reviewed

Permits & policy.

The regulatory landscape — LADBS, SB-9, coastal, hillside, HPOZ, and what they mean for your lot.

IV

Chapter IV · 4 entries · reviewed

Renting & living.

What you can and can't do with the unit once it's built — Airbnb, family, full-time tenants.

V

Chapter V · 5 entries · reviewed

The studio & how we work.

Who we are, how the contract works, and what to expect from us as a partner.

The end of the reference

Question we didn't answer?

Share the property address and proposed scope. RSA can review the context and identify the questions, documents and appropriate next step.

Start here

Three answers most Los Angeles homeowners need first

Where do I start with an ADU, addition or remodel?

Confirm which city governs the parcel, collect permit history and zoning, then define scope before relying on any price. Project Studio turns those answers into a printable brief.

Questions by city ordinance

State law sets the floor. The decisions are made city by city.

California legislation applies across all 88 cities below, but each city publishes its own code, overlays, fees and review process. Every row names the conditions on record for that jurisdiction, links to its own question set and planning guide, and cites the city's published source.

Westside · 8

  • Agoura Hills

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Protected-tree review may shape siting before a concept plan is fixed.

  • Beverly Hills

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized. · High-value residential work benefits from disciplined scope definition and coordination across design, engineering and construction.

  • Calabasas

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Protected-tree review may shape siting before a concept plan is fixed.

  • Culver City

    Studio and media districts create a varied context of homes, employment uses and active commercial corridors. · Residential and mixed-use districts can follow different zoning and entitlement paths. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Hidden Hills

    Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Malibu

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Santa Monica

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Residential and mixed-use districts can follow different zoning and entitlement paths. · Historic districts or resources can affect demolition, additions, exterior changes and documentation.

  • West Hollywood

    A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · Residential and mixed-use districts can follow different zoning and entitlement paths. · Objective standards and design review should be identified before exterior form and materials are finalized.

San Gabriel Valley · 30

  • Alhambra

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Residential and mixed-use districts can follow different zoning and entitlement paths.

  • Arcadia

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Azusa

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Baldwin Park

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Residential and mixed-use districts can follow different zoning and entitlement paths.

  • Bradbury

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · With little vacant land, reuse, additions and careful site planning often matter more than greenfield assumptions.

  • Claremont

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Tree preservation and mature canopy conditions can shape footprint, access and consultant needs. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Covina

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot.

  • Diamond Bar

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Duarte

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Wildland-urban interface conditions can affect materials, access and agency coordination. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • El Monte

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Residential and mixed-use districts can follow different zoning and entitlement paths.

  • Glendora

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Historic districts or resources can affect demolition, additions, exterior changes and documentation.

  • Industry

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · The city has a limited residential footprint, so confirming zoning and permitted use is the first filter.

  • Irwindale

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · The city has a limited residential footprint, so confirming zoning and permitted use is the first filter.

  • La Habra Heights

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · With little vacant land, reuse, additions and careful site planning often matter more than greenfield assumptions.

  • La Puente

    A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • La Verne

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Monrovia

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Transit-adjacent sites may have planning rules and development opportunities distinct from nearby residential blocks.

  • Montebello

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Monterey Park

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot.

  • Pico Rivera

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Pomona

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Residential and mixed-use districts can follow different zoning and entitlement paths. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Rosemead

    Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • San Dimas

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Wildland-urban interface conditions can affect materials, access and agency coordination.

  • San Gabriel

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • San Marino

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Tree preservation and mature canopy conditions can shape footprint, access and consultant needs. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • South El Monte

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · Proximity to river and flood-control systems makes mapped flood conditions an early due-diligence item. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • South Pasadena

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Transit-adjacent sites may have planning rules and development opportunities distinct from nearby residential blocks. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Temple City

    Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Walnut

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • West Covina

    Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

Gateway/Southeast · 20

Harbor/Island · 2

  • Avalon

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Island logistics and limited access require early coordination of delivery, staging and utilities. · With little vacant land, reuse, additions and careful site planning often matter more than greenfield assumptions.

  • Long Beach

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Port and waterfront districts create distinct land-use, environmental and access contexts. · Residential and mixed-use districts can follow different zoning and entitlement paths.

Central LA/Foothills · 8

  • Burbank

    Studio and media districts create a varied context of homes, employment uses and active commercial corridors. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Glendale

    Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Residential and mixed-use districts can follow different zoning and entitlement paths.

  • La Cañada Flintridge

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Los Angeles

    The applicable community plan, specific plan and zoning overlays depend on the exact Los Angeles address. · Residential and mixed-use districts can follow different zoning and entitlement paths. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility.

  • Pasadena

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • San Fernando

    Historic districts or resources can affect demolition, additions, exterior changes and documentation. · Residential work near industrial land requires close attention to use boundaries, access and site conditions. · A compact urban lot rewards precise measurement of access, setbacks and existing improvements.

  • Sierra Madre

    Foothill conditions can combine slope, drainage, fire-access and neighborhood-character considerations. · Wildland-urban interface conditions can affect materials, access and agency coordination. · Historic districts or resources can affect demolition, additions, exterior changes and documentation.

  • Vernon

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · The city has a limited residential footprint, so confirming zoning and permitted use is the first filter.

South Bay · 16

  • Carson

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • El Segundo

    Airport proximity can introduce noise, height or land-use compatibility checks for some properties. · Residential work near industrial land requires close attention to use boundaries, access and site conditions. · Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset.

  • Gardena

    On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot.

  • Hawthorne

    Airport proximity can introduce noise, height or land-use compatibility checks for some properties. · Residential work near industrial land requires close attention to use boundaries, access and site conditions. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Hermosa Beach

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Inglewood

    Residential and mixed-use districts can follow different zoning and entitlement paths. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs. · Airport proximity can introduce noise, height or land-use compatibility checks for some properties.

  • Lawndale

    A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Lomita

    A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · Corridor properties may involve use, access, parking and design-review questions beyond a typical house lot.

  • Manhattan Beach

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · A compact urban lot rewards precise measurement of access, setbacks and existing improvements. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Palos Verdes Estates

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Rancho Palos Verdes

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Mapped ground movement and geologic conditions require property-specific professional review before design commitments.

  • Redondo Beach

    Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset. · Residential and mixed-use districts can follow different zoning and entitlement paths. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Rolling Hills

    Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Rolling Hills Estates

    Large-lot and equestrian conditions can introduce access, grading, drainage and accessory-use questions. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Objective standards and design review should be identified before exterior form and materials are finalized.

  • Signal Hill

    Legacy oil activity can require records research and site-specific environmental coordination. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · On established blocks, existing structures, utilities and neighbor-facing edges are central design inputs.

  • Torrance

    Residential work near industrial land requires close attention to use boundaries, access and site conditions. · Residential and mixed-use districts can follow different zoning and entitlement paths. · Coastal-zone location can add a separate review layer; parcel status should be confirmed at the outset.

Antelope Valley · 2

  • Lancaster

    High-desert projects require climate-responsive design and careful utility and site planning. · Larger parcels expand options but still require zoning, utility and access verification. · Solar exposure and high-desert climate are important inputs for envelope and energy planning.

  • Palmdale

    High-desert projects require climate-responsive design and careful utility and site planning. · Larger parcels expand options but still require zoning, utility and access verification. · Aerospace and employment districts create land-use patterns distinct from surrounding residential areas.

North County · 2

  • Santa Clarita

    Wildland-urban interface conditions can affect materials, access and agency coordination. · Hillside lots can add grading, drainage, access and geotechnical questions to early feasibility. · Master-planned areas may combine city standards with tract, association or design-guideline requirements.

  • Westlake Village

    Master-planned areas may combine city standards with tract, association or design-guideline requirements. · With little vacant land, reuse, additions and careful site planning often matter more than greenfield assumptions. · Objective standards and design review should be identified before exterior form and materials are finalized.

Confirm anything decision-critical against the city's own published source and the responsible state or regional authority, and record the date you checked — forms, fees and thresholds change.