Frequently Asked Questions
What are ADUs?
ADUs – also called granny flats, second units, and casitas – can meet the changing needs of your family over time, including a home for loved ones, additional income, and an option to downsize after you retire. They can be attached or detached from the main home, and are generally between 150 and 1,200 square feet. ADUs are allowed to be built on most properties in California with limited exceptions.
How do I use the ADU Plans Gallery?
The Plans Gallery can help you at various stages of an ADU project. When you’re just getting started, you can browse for inspiration on design, layout, and features. When you have a clearer picture of what you are looking for and what fits on your property, you can select a design and contact the designer or company for more details (inclusion in the gallery does not constitute endorsement of an individual designer or company). We invite you to use the various features of the Gallery, including filtering for construction type, square footage, number of bedrooms, and features important to you. You can also mark favorite plans and return to your favorites later!
What are pre-approved ADU plans?
Pre-approved plans have been pre-reviewed for building code by a local, state, or federal government, reducing review time for the rest of the permitting application to 30 days.* They are general and not tied to a specific property, including structural, roof, and floor plans, and cannot be customized much beyond materials to qualify for the expedited review. Our gallery includes site-built plans, which are built from scratch on your lot, and prefabricated plans, which are fully or partially built off-site and delivered to your property.
Why do I see plans that aren’t pre-approved? The gallery includes designs from trusted designers that have not yet been reviewed for building code. You can use these plans and then continue customization and permitting without expedited review – but still save substantial time and money over a fully custom design.
What do I do after I pick a design? You can contact the designer directly and/or access the plans online, then work with the original designer or another professional to complete site planning and file all necessary applications. Contact staff with questions about what’s required and the application process at: planningdept@mariposacounty.org or by calling 209-966-5151.
How much do plans typically cost? Designers set the price to use their plans or purchase prefabricated units, and costs can vary based on what is included in the plans. The gallery also includes free or very low-cost plans provided by other government agencies or nonprofit organizations.
I have a unique property or live in a special zone – can I use these plans? Possibly! Designs typically include the main structure and not the foundation or other site-specific elements, so it depends on the rules for your area. Galleries include a WUI Compliant filter for areas that require that WUI building materials be used.
I am having trouble using the ADU Plans Gallery, what do I do?
Please go to ADUAccelerator.org/docs/homeowners for instructions and helpful articles. If you are still having trouble, please contact support@aduaccelerator.org with a description of your issue.
The ADU Plans Gallery is maintained by Mariposa County, developed by Community Planning Collaborative.
*Applies to jurisdiction reviews; any reviews by outside agencies may take more than 30 days.
