Everything You Need to Know to Build an ADU
What is an ADU?
ADU (also “second unit” or “granny unit”), short for Accessory Dwelling Unit, means an attached or detached residential dwelling unit, situated on the same lot as an existing primary single-family dwelling. The ADU provides complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation.
Homeowners are scrambling to add value to their properties by building Accessory Dwelling Units (ADUs), a.k.a. guest houses or granny flats. In Los Angeles alone, permit applications spiked a whopping 2,500% from 2016 to 2017. ADU’s accounted for 23% of all plans permitted in Los Angeles in 2019.
Want to build an ADU? Here’s what you need to know to obtain a permit for an ADU:
- An ADU may be built on Single Family Residence zoned lots and on Multifamily lots.
- The ADU is a structure that is in addition to a main house, whether attached or detached.
- Different from a “tiny house”, it cannot stand alone on a lot.
- It is not permitted to have an ADU in the front half of the property.
- One ADU and one Junior ADU are allowed per lot.
- Depending on the city, the ADU may be as large as 1,200 square feet.
- The minimum size varies, but can never be less than 150 square feet.
- An ADU must contain a full restroom, kitchenette, 1 to 3 bedrooms, and a living area.
- An ADU may not require additional parking space if located close to public transit.
Each city and county has its own requirements for obtaining a permit for an ADU. You should always seek the advice of a licensed architect with specific residential ADU experience.
New Standalone ADU
ADU Above Garage
Can an ADU be on the second floor?
Yes, in most municipalities, and the ADU can have its own private entry or it may have an entry within the existing main dwelling.
Can an ADU be a two story structure?
Yes in most cities.
How far must I be from my neighbor’s property line?
The setbacks, or minimum distances from your property line, and heights will vary by district. Most cities do not require more than a four foot side and rear yard setback. Be sure to speak with a licensed architect.
What are my parking requirements?
Many cities may not require replacement parking when a garage, carport or covered parking is converted or demolished to create an ADU, or is converted to an ADU. In lieu of an additional parking space, required for an ADU, you may qualify for an exemption if your ADU is within half a mile of a local bus stop.