The best place to start is by 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 our Process-At-A-Glance resource for an overview of the steps and some initial issues to consider as you get started.

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 local staff, 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.

ADUs and JADUs are allowed in any zone that allows single family or multifamily homes and can be added to existing or proposed homes.

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 you can get permits.

If your property has an onsite septic system, you will likely need to apply for additional permits from the Alameda County Department of Environmental Health (DEH). It is important to know this early on in the process and meet with DEH to see if you are able to accommodate an ADU on your property. If you can, the permit process can add months and significant costs to the process of building.