Are you interested in building an ADU in California? If yes, there are quite a few rules and regulations you need to be aware of. However, we are just going to focus on ADU size limits in California.
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Size Limits Differ
Depending on where you live in California will determine what size limits apply to you. Cities are broken up into different zones, and every zone has its own regulations. So, your neighbor might be able to build a huge ADU, but the zone line falls in between you two so you can only build an 800 square-foot unit.
This is why it is important to talk to your local government about what zone you fall in and what ADU zoning laws apply to you. If you don’t want to talk to your local planning board, you can always hire an ADU professional who is local to your area. They will have a vast knowledge of the zoning laws and will be able to figure it all out for you so that you don’t have to spend all your time in the research phase of construction.
General ADU Max Sizes
As we mentioned before, ADU regulations in California vary by region. However, generally speaking, an ADU can usually be up to 1,200 feet if it is a detached unit. If the ADU is an attached unit, it can be up to 50% of the primary house’s square footage. If it is a JADU, it can be up to 500 square feet.
Everywhere you go will always have the maximum square footage of at least 800 square feet. If your region’s maximum is below this, you can argue that those rules are unenforceable.
General ADU Minimums
Generally speaking, your ADU can be as small as 150 square feet regardless of what type it is. This would be a very small unit though, and just barely be able to fit the mandatory kitchen, bathroom, and living space requirements.
If you want to go smaller, you can apply for a discretionary permit. However, you will likely be denied, but it is worth a shot.
