Phase 4


  • Identify what you want in a design
  • Understand the design process and professionals involved
  • Hire a professional team to create your design

Once you have a sense of what you want to build, know what you can build, and have estimated your budget, you can start designing your ADU, which begins with design inspiration and ends with permit-ready plans.


The Design phase typically takes 1-6 months. Most ADU projects take 12-18 months to complete, but some extend to 24 months or more.



Before you begin: It is helpful to have a clear sense of what you want early in the process. An architect or designer can help you brainstorm, but they cannot start designing until you’ve made basic decisions like the type of ADU you want (see Get Started) and how many bedrooms it will have. Our ADU Worksheets can help you think about these questions.

Step 1

Consider the county's "Permit-Ready" Plans

COMING SOON! El Dorado County is currently developing options for “permit-ready” plans that will have already been reviewed by appropriate departments and agencies, saving you time and money. Stay tuned for more information.

Step 2

Hire Experienced Professionals

Although you can build an ADU as an owner builder, we strongly recommend hiring a licensed architect or designer and a licensed contractor, or a design/build team, and most homeowners do. Bringing on a professional early in the process is often key to getting your ADU approved quickly, managed efficiently, and built cost-effectively. Relevant experience and fit are critical, and it’s important to look at their past work and check references.

Our Contractor List provides options for professionals working on ADUs in our area and our ADU Worksheets include a list of questions to consider when hiring a team.

Your team may include one or more of the following:

  • Licensed architect or designer to design your ADU and potentially see you through permitting and construction
  • Licensed contractor to build your ADU
  • Design/build company that designs and builds your ADU
  • Modular/prefab company who sells preset designs for modular/prefab homes

Unincorporated El Dorado County: ADU plans must be stamped by either a licensed architect or a licensed engineer.

City of Placerville: plans do not need a licensed professional stamp unless it requires engineering under building code requirements (for instance: a bearing stem wall).

Step 3

Create Initial Design

Once you have your team in place, you will work with them to design your ADU. Together you will consider size, use, layout, specific project needs (storage, laundry room, etc.), architectural style, and privacy.

First, you’ll likely get conceptual drawings – drawings based on measurements of your property (perhaps a property survey), local rules, and the type and size of ADU you want. These drawings can also be helpful in finalizing what you want.

Once conceptual drawings have been approved, you’ll get refined drawings that include structural and design components.

Once you have an initial design, it’s a good idea to discuss it with local staff so they can point out any issues before submitting your permit application. Your design team can attend this meeting to clarify drawings and help you understand requirements.

If you haven’t already, this is also a good time to reach out to utility service providers (water, sewer, gas, etc.) to confirm your design meets their requirements. See the Contact page for all relevant contact information.


Find answers to the most frequently asked questions about ADU design.

Find a professional

Check out our Contractor List for professionals who work on ADUs in our area


Tell us your thoughts!

Please give us feedback about ADUs in our area. If you leave your contact info, we may be able to get back to you with more information. 

If you’re looking for specific advice or information about your property and ADU, please use the contact information for El Dorado County or the City of Placerville at the bottom of this website. 

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