ADU Plans Los Angeles: Costs And Tips

Accessory Dwelling Units (ADUs) are becoming increasingly popular as a housing solution, offering flexibility and additional living space on residential properties. In this blog, we’ll explore the various types of ADUs, delve into the key elements that go into creating ADU plans, discuss the process of working with an ADU designer, shed light on the costs involved, and provide insights into the timeline for plan creation and city checks. Additionally, we’ll examine the pros and cons of pre-approved city ADU plans, helping you make an informed decision about your ADU project

Here at GreatBuildz, a free service that connects homeowners in Los Angeles with reliable general contractors, we speak to homeowners every day about the details of their ADU or garage conversion project.


We’ve worked on hundreds of accessory dwelling units and other remodeling projects throughout Los Angeles and have found that a meticulous plan will always yield the best results. Here is some information about the general costs and tips one should definitely consider when beginning their ADU project.

ADU plans for design and layout planning

Types of ADUs

There are several types of ADUs that homeowners can consider, each with its own unique features and benefits.

  • Detached ADU – This unit is a separate structure that is physically detached from the main dwelling. It can be a standalone cottage, a converted garage, or a newly constructed building in the backyard.
  • Attached ADU – This unit is connected to the main house, either through a shared wall or by being built as an extension of the existing structure. 
  • Garage Conversions – Homeowners can transform their existing garages into livable spaces, such as studios, apartments, or guest suites.
  • Junior ADUs (JADUs) – These are smaller units typically created by converting a portion of an existing home, such as a bedroom or a basement. JADUs have their own entrance and may have separate kitchen and bathroom facilities.ADU architect and designer

Anatomy of an ADU Plan

To create a set of ADU plans, several important factors and considerations need to be taken into account.

  • Design Layout – The design layout of an ADU is a crucial aspect of the planning process. It involves determining the size, room configurations, and overall flow of the unit. 
  • Structural Considerations – ADU plans should address the structural aspects of the unit, including the foundation, framing, roofing, and exterior finishes. 
  • Plumbing and Electrical Systems – The plans should incorporate the plumbing and electrical requirements of the ADU. This includes the placement of fixtures, outlets, and switches, as well as the layout of plumbing lines, drains, and ventilation systems. 
  • HVAC and Mechanical Systems – The plans should specify the heating, ventilation, and air conditioning (HVAC) system for the ADU, considering the size and layout of the unit. Additionally, any mechanical systems such as water heaters or ventilation fans should be addressed in the plans.
  • Interior Finishes – The selection of interior finishes, such as flooring, wall finishes, and cabinetry, should be outlined in the plans. 
  • Accessibility Features – Incorporating accessibility features, such as ramps, wider doorways, and grab bars, may be necessary depending on local accessibility requirements or the specific needs of the occupants.
  • Lighting and Ventilation – The plans should indicate the placement of windows, skylights, and artificial lighting fixtures to ensure sufficient natural light and ventilation within the ADU.
  • Permitting and Code Compliance – ADU plans must comply with local building codes and regulations. This includes setbacks, height restrictions, fire safety measures, and any other requirements specific to the area.
    anatomy of ADU plan

How to Get Started Creating ADU Plans with a Designer or Architect

Getting started with creating ADU plans involves collaborating with an ADU architect or designer who specializes in ADU design and construction. The following steps can help homeowners initiate the process:

  • Research and Identify Potential Designers/Architects – Begin by researching and identifying professionals who have experience and expertise in designing ADUs. Look for individuals or firms with a portfolio that showcases their ADU blueprints and a track record of successful designs.
  • Consultation and Site Assessment – Schedule an initial consultation with the designer or architect to discuss your goals, requirements, and vision for the ADU. During this meeting, they will likely conduct a site assessment to evaluate the feasibility and constraints of the property.
  • Budget and Design Considerations – Discuss your budget with the designer or architect. They can help you understand the potential costs involved in constructing an ADU and provide guidance on design options that align with your budget. 
  • Conceptual Design and Layout – Once the designer or architect has a clear understanding of your needs and budget, they will start developing a conceptual design and layout for the ADU. This will include considerations such as room configurations, overall size, exterior aesthetics, and interior functionality. 
  • Permitting and Code Compliance – The designer or architect will navigate the permitting process on your behalf. They will create detailed ADU plans that comply with local building codes and regulations. They will also assist in obtaining the necessary permits and approvals from the local planning department.
  • Collaboration and Iteration – The design process is iterative, with multiple rounds of feedback and revisions. Collaborate closely with the designer or architect, providing your input and preferences throughout the design development. 
  • Construction Documentation – Once the design is finalized, the designer or architect will create detailed construction documentation. These documents include architectural drawings, structural plans, plumbing and electrical layouts, and specifications for finishes and materials.
  • Engaging Contractors – Your designer or architect may be able to recommend trusted contractors experienced in building ADUs. Alternatively, you can request bids from multiple contractors and select the one that aligns with your budget and project requirements. 

ADU planning and discussion with expert

Costs of ADU Plans and Permits in LA

The cost of ADU plans typically depends on the complexity and size of the project, as well as the specific requirements of the homeowner. Designers or architects usually charge a fee based on a percentage of the total construction cost or a flat fee. ADU plan costs in Los Angeles can range from $5,000 to $20,000 or more.

Obtaining permits for an ADU in Los Angeles also incur certain fees. Permit fees in the city can range from a few thousand dollars to upwards of $10,000, depending on the scope of the project. These fees cover the costs associated with plan review, inspections, and other administrative processes.

It’s important to note that these costs are specific to ADU plans and permits. They do not include the overall construction costs, which involve labor, materials, and other expenses associated with building an ADU. The total cost of an ADU project will also depend on factors such as the size, complexity, and desired finishes of the unit.

It’s worth exploring whether any fee waivers or incentives are available for ADU construction in Los Angeles. The city has offered fee waivers for certain ADU projects in the past.

Additionally, homeowners may be eligible for incentives or financial assistance programs that can help offset some of the costs associated with ADU development.

red backyard ADU plans

Timeline of ADU Plan Creation and ADU Plan Checks

The timeline for creating ADU plans typically depends on the complexity of the project, collaboration with the designer or architect, and the homeowner’s decision-making process. It may take several weeks to a few months to finalize the design, incorporating the homeowner’s preferences and ensuring compliance with local regulations.

The permitting process in Los Angeles can take around three to six months or more. This timeline includes the review and approval of the ADU plans by the city’s building department, addressing any comments or modifications, and obtaining the necessary permits.

Several factors can affect the timeline for ADU plan creation and city plan checks. These include the workload of the local building department, the complexity of the project, the accuracy and completeness of the submitted plans, and any potential revisions or additional documentation requested by the city during the review process.

In some cases, expedited review options may be available for ADU projects. The Los Angeles Department of Building and Safety has introduced expedited processing for certain ADU applications, aiming to shorten the review and approval timeline. However, availability and eligibility for expedited review may vary.

Should You Use a City Pre-Approved Plan?

City pre-approved ADU plans, also known as standardized or pre-designed ADU plans, are a concept implemented by some cities to streamline the ADU approval process. These plans are typically created by the city or a designated agency and are intended to meet certain requirements and design guidelines established by the local jurisdiction.

While city pre-approved ADU plans can offer certain advantages, it’s important to consider their limitations, which may explain why they may not work for most people:

  • Limited Customization – Pre-approved ADU plans are designed to meet general standards and guidelines, which may not accommodate specific preferences, needs, or unique site conditions. 
  • Site-specific Considerations – Each property and location has its own characteristics and constraints. Pre-approved ADU plans may not take into account the specific topography, orientation, setbacks, or utility connections of an individual property.
  • Style and Aesthetics – Pre-approved ADU plans may have a specific architectural style or aesthetic that may not align with individual tastes or match the existing main dwelling on the property. 
  • Compliance with Changing Regulations – Pre-approved ADU plans may not always align with the most recent building codes, zoning regulations, and ADU policies, leaving homeowners with outdated plans that may not meet current regulations. 
  • Unique Property Constraints – Some properties may have unique challenges or constraints, such as irregular lot sizes, existing structures, or historic preservation requirements. Pre-approved ADU plans may not address these specific considerations, requiring customized designs to navigate these complexities.

If you’re working on developing plans for an ADU in the Los Angeles and Southern California areas, GreatBuildz can introduce you to the best local contractors to bring your dreams to life. GreatBuildz is a free service that matches homeowners with reliable, thoroughly screened general contractors. Call (818.317.3567) or visit our website to be matched with a professional, pre-vetted ADU contractor.

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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