Question 1

What is an ADU?

Accepted Answer

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family or multifamily residential lot. They're also called granny flats, casitas, in-law suites, or backyard homes. California law now makes them easier than ever to build.

Question 2

What types of ADUs can I build?

Accepted Answer

There are four common types: a detached ADU (a standalone backyard structure), an attached ADU (an addition to your existing home), a garage conversion, and a Junior ADU (JADU) up to 500 sq ft carved out of your existing home footprint.

Question 3

How many ADUs can I build on my property?

Accepted Answer

On a single-family lot you can typically build one detached ADU (up to 1,200 sq ft), one attached ADU, and one JADU (up to 500 sq ft) — up to three units total. Multifamily properties can add up to eight detached ADUs plus interior conversions of up to 25% of existing units.

Question 4

Do I have to live on the property to build an ADU?

Accepted Answer

No. Owner-occupancy is no longer required for standard ADUs — California made this permanent as of 2026. (A JADU still carries an owner-occupancy requirement.)

Question 5

How big can a Junior ADU (JADU) be?

Accepted Answer

A JADU is capped at 500 sq ft and must be created within the existing footprint of your home — typically by converting a bedroom, office, or part of an attached garage.

ADU Basics — Everything You Need to Know

Four kinds of ADU.

How many ADUs can I build?

California ADU law.

Who builds ADUs?

Is an ADU right for me?

Questions, answered.