Building an ADU is an investment of time as well as money. Most projects take one to two years to complete. Typically, it takes homeowners one to three months to get started and assemble their team, then one to six months to develop plans, meet with the city, and submit the application. Depending on what permits are required, how many rounds of review are required and how quickly a homeowner and their project team can respond to comments, it will take one to six months to get permits. Construction usually takes six to twelve months.

You’re not required to tell your neighbors about your ADU, but it’s always a good idea to communicate with them early in the process. Your project will run more smoothly if they are kept informed, and they may have great ideas for your project!

If you live in a Neighborhood or Homeowners Association, talk with your representative or board early in the process. They can’t prevent you from building or renting an ADU, but they may have guidelines you’ll need to know for design and construction. Depending on where you live, written approval from your HOA may be required before your location will permit your ADU.

ADUs often need separate waste treatment and your system may need to be modified. Contact your Environmental Health Department early in the process. For contact information, see the Contact page.

ADUs may require a well report and well systems may need to be upgraded. Contact your County Environmental Health Department early in the process. For contact information, see the Contact page.

The best place to start is with thinking about what you want, understanding your goals and concerns, and looking at other ADUs for inspiration. Once you have some ideas in mind, you can consider your budget and move on to Learning the Rules to figure out what you can build on your property.

You can also use your County Process-at-a-Glance resource for an overview of the steps and some initial issues to consider as you get started.