New Pre-Approved ADU Plans Program: Free Plans From California HCD

California Is Giving Away Free ADU Plans — Here's How to Get Them

In a bold move to accelerate ADU construction across the state, the California Department of Housing and Community Development (HCD) has launched a pre-approved ADU plans program. This initiative provides homeowners with professionally designed, code-compliant ADU plans at no cost — eliminating one of the biggest barriers to building an accessory dwelling unit.

If you've been thinking about building an ADU but felt overwhelmed by design costs and permitting timelines, this program could be exactly what you need. Let's break down everything you need to know about California's pre-approved ADU plans.

What Are Pre-Approved ADU Plans?

Pre-approved ADU plans are architectural designs that have already been reviewed and certified by the state of California to meet building code requirements. When a city accepts these plans, homeowners can skip much of the traditional plan-check process — potentially saving weeks or even months of permitting time.

How the Program Works

HCD certifies plans: Professional architects submit ADU designs to HCD for review against state building codes
Plans are published: Approved designs are made available through HCD's website and participating cities
Homeowners select a plan: You choose a design that fits your lot and needs
Streamlined permitting: Cities that participate in the program accept pre-approved plans with minimal additional review
Local adaptations: Some site-specific engineering (foundation, soils) may still be required

What's Included in Pre-Approved Plans

Typical pre-approved plan sets include:

Architectural drawings: Floor plans, elevations, roof plans, sections
Structural engineering: Framing plans, foundation details, connection schedules
Title 24 energy compliance: Energy calculations for the specific design
Plumbing and electrical layouts: Basic MEP (mechanical, electrical, plumbing) plans
Specification sheets: Materials and finish specifications

Available Plan Types and Sizes

The pre-approved plans library includes a variety of ADU configurations to suit different lot sizes and homeowner needs:

Studio ADUs (400–500 sq ft)

Open-concept living/sleeping area
Full kitchen and bathroom
Ideal for rental income or home office
Typically the fastest and most affordable to build

One-Bedroom ADUs (500–750 sq ft)

Separate bedroom and living area
Full kitchen and bathroom
Best balance of livability and construction cost
Most popular configuration for long-term rentals

Two-Bedroom ADUs (750–1,200 sq ft)

Two separate bedrooms
Full kitchen, living room, and one or two bathrooms
Maximum rental value
Great for family members or premium rental market

Junior ADUs (up to 500 sq ft)

Converted from existing space within the main home
Efficiency kitchen (small sink, cooking appliance, counter)
Separate entrance required
Most affordable option — learn more about JADUs

How Much Money Can You Save?

The financial benefits of using pre-approved plans are significant:

Design Cost Savings

Custom architectural plans for an ADU requires a property-specific written estimate depending on complexity. Pre-approved plans eliminate this cost entirely, or reduce it to a fraction for site-specific adaptations.

Permitting Time Savings

Traditional ADU plan check takes 4–12 weeks in most Southern California cities. Pre-approved plans can reduce this to as little as 1–3 weeks, since the building department doesn't need to review the structural and architectural design from scratch.

Reduced Correction Rounds

One of the biggest delays in permitting is correction letters — where the city asks for changes to your plans. Pre-approved designs have already passed rigorous state review, dramatically reducing the chance of corrections.

Overall Impact

Between design savings and faster permitting, homeowners using pre-approved plans can save approximately a property-specific written estimate and 2–4 months compared to the traditional custom design route.

Which Cities Accept Pre-Approved Plans?

As of 2026, participation varies by city. Here's what we're seeing across Southern California:

Cities with Active Pre-Approved Plan Programs

Los Angeles: The city's Standard Plan Program offers multiple pre-approved designs
San Jose: One of the earliest adopters with a robust library
San Diego: Accepts state-certified plans with minimal additional review
Long Beach: Actively promoting pre-approved plans to streamline ADU permits — see our Long Beach projects

Cities Developing Programs

Many cities in Los Angeles and Orange County are in various stages of adopting pre-approved plan programs. Even cities without formal programs may accept HCD-certified plans with expedited review.

How to Check Your City

Visit your city's building department website
Call the planning counter and ask about pre-approved ADU plans
Check HCD's website for the latest list of participating jurisdictions
Contact Vision ADU — we track program availability across all the cities we serve

Limitations and Considerations

While pre-approved plans offer tremendous benefits, they're not a perfect fit for every situation:

Site-Specific Requirements

Even with pre-approved plans, you'll likely need:

Soils report: Your specific soil conditions determine foundation requirements
Site plan: Showing exactly where the ADU sits on your lot, setbacks, and utilities
Utility connections: Engineering for sewer, water, and electrical connections to your property
Grading plan: If your lot has significant slope

Design Limitations

Pre-approved plans are standardized designs. They may not:

Maximize every square foot of your available space
Match your main home's architectural style perfectly
Include custom features you want (vaulted ceilings, unique window configurations)
Account for unusual lot shapes or constraints

When Custom Design Makes More Sense

Consider custom plans if:

Your lot has unusual dimensions or significant slope
You want the ADU to closely match a distinctive home style
You need specific accessibility features
You're building a two-story ADU on a challenging site
You want to maximize the allowed square footage for your specific lot

How to Use Pre-Approved Plans Effectively

Step 1: Evaluate Your Property

Before selecting a pre-approved plan, assess your property:

Measure available space (accounting for setbacks — typically 4 feet from rear and side property lines)
Check your lot's zoning designation
Identify utility connection points
Note any slopes, trees, or easements that affect placement

Step 2: Choose the Right Plan

Select a plan that:

Fits within your available buildable area
Meets your goals (rental income vs. family housing)
Stays within your budget
Complements your existing home as much as possible

Step 3: Get Site-Specific Engineering

Even with pre-approved architectural plans, you'll need:

A licensed surveyor to prepare a site plan
A geotechnical engineer for soils testing
Possibly a civil engineer for drainage and utility connections
Foundation modifications based on your soils report

Step 4: Submit for Permits

Work with your builder or permit expediter to submit:

The pre-approved plan set
Site-specific engineering documents
Required application forms and fees
Any city-specific supplemental documents

Step 5: Build

Once permitted, construction proceeds like any ADU project. Learn about our construction process.

Combining Pre-Approved Plans with Professional Building

At Vision ADU, we can work with pre-approved plans or create custom designs — whatever makes the most sense for your project. Many of our clients start with a pre-approved plan and then work with our team to make site-specific modifications that optimize the design for their property.

Our Approach

Free property assessment: We evaluate your lot and help you determine whether pre-approved or custom plans are the better choice — get your assessment
Plan adaptation: If a pre-approved plan is close but not perfect, our architects can modify it for your specific needs
Full-service construction: Whether using pre-approved or custom plans, we handle everything from permitting through construction to final inspection

The Future of Pre-Approved Plans

California continues to expand and improve the pre-approved plans program:

More design options: New plans are being added regularly, including modern, traditional, and contemporary styles
Accessory structure integration: Plans that include garages, carports, or workshops alongside the ADU
Sustainability features: Designs that exceed Title 24 minimums with solar-ready roofs, EV charging, and water conservation features
Prefab compatibility: Plans designed for factory-built components that can reduce construction time

Take Action: Start Your ADU Project Today

Whether you use pre-approved plans or opt for a custom design, the most important step is getting started. California's favorable ADU regulations won't last forever in their current form, and construction costs continue to rise.

Check availability: Visit HCD's website or contact us to learn which pre-approved plans are available in your city
Assess your property: Get a free property assessment to understand your ADU potential
Compare options: Our team can help you weigh pre-approved vs. custom plans for your specific situation
Start building: The sooner you begin, the sooner you'll have rental income or additional living space

Pre-approved plans still need to be built by a qualified team, and local review habits differ from city to city — including Sherman Oaks, North Hollywood, and Woodland Hills. For help choosing a builder, see our guide on how to hire an ADU contractor near you.

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Vision ADU helps homeowners across Los Angeles and Orange County navigate every aspect of ADU construction — from plan selection through move-in day. Whether you choose pre-approved plans or a fully custom design, we're here to make the process smooth and stress-free. Book your free consultation today.