Phase 4
Design
- 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.
Timeline
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.
Design
Step-by-Step
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 "Pre-Reviewed" Plans
NOW HERE! El Dorado County has developed Pre-Reviewed ADU Plans that have been examined by the appropriate departments and agencies; ultimately, saving you time and money.
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: ADU plans do not need a licensed professional stamp unless it requires engineering under building code requirements (for instance: a bearing stem wall).
TOOLS AND RESOURCES
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 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.
TOOLS AND RESOURCES
Site-built/Traditional: A traditionally constructed ADU is designed and built specifically to your preferences and property and built on site (“stick-built”). This option allows for a lot of customization and smaller changes to be made throughout the construction process.
Prefabricated/panelized/modular: These ADUs are partially or mostly built in a factory, then shipped to your site to be put together. Sometimes the company will include all services in their fee (“turn-key”), including help with permitting and all on-site construction tasks (e.g., laying the foundation, utility hookups, etc.). Other times you’ll need to hire additional professionals to help.
Sewer Districts and Onsite Septic Systems: If your property is outside of a sewer service district, you will need to find out if your septic system will meet local requirements when adding an ADU to your property. You may have to increase your septic capacity (add a new tank) or establish a new water source, which can be an unexpected cost, so talk to the El Dorado County Environmental Management Department early in the process to find out (see the Contact page for details).
Water Wells: If your home is not served by the public water system, El Dorado County Environmental Management will require a capacity report to ensure the existing water well is adequate for an additional residence. You must submit a perc test, septic design, and well production report to Environmental Management (with or after building permit application).
City of Placerville: Septic systems are not permitted in the City unless the public sewer main is greater than 200 feet from the residence. Septic systems require a permit application, a review and an approval by the El Dorado County Environmental Management Department.
Most homeowners choose to work with some type of design professional to plan their ADU and help throughout the process. 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 will be critical.
There are a variety of types of designer, and they may be an architect, builder, “designer,” design/build, or a modular/prefab company. If you’re hiring a local individual or team, they’ll likely start the process by visiting your home and talking to you about your ideas and goals. If it seems like a good match, they will prepare a proposal detailing their services and fee. Professionals typically charge for an initial consultation or proposal.
The American Institute of Architects provides helpful information for homeowners and maintains a local Central Valley chapter website where you can find professionals accepting new work.
You can also check out our Contractor List to see if it includes any design professionals who interest you.
See our ADU Worksheets for a list of questions to ask a potential architect or designer.
Once you have a design established with your architect/designer, it’s a great idea to discuss it with Planning staff so they can point out any issues before you prepare your application. See our ADU Worksheets for questions you might want to ask.
Your ADU may be expected to comply with objective design standards, such as roof pitch, landscaping guidelines, and others. For instance, City of Placerville properties in Historic Districts require a review for consistency with historical criteria, and ADUs in architecturally controlled Community Services Districts require architectural approval before building permits are issued. Confirm applicable design guidelines with local staff before beginning the design process.
El Dorado County is currently working on permit-ready ADU plans that will save you time and money in the design and permitting process. When those plans are ready, this site will point you in the right direction.
Find a professional
Check out our Contractor List for professionals who work on ADUs in our area
