What an ADU is
An ADU is a self-contained living unit with its own kitchen, bathroom and entrance, located on the same lot as a primary residence. Families build them for aging parents, adult children, rental income, a home office or guests. California law has made them easier to build by limiting the restrictions cities can place on them, though local rules still apply.
Types of ADUs
| Type | What it is | Often a fit when |
|---|---|---|
| Detached ADU | A new, separate building in the backyard | You have yard space and want privacy for both households |
| Attached ADU | An addition connected to the main house | The lot is tight but you can extend from the house |
| Garage conversion | An existing garage turned into living space | You have a usable garage and want a faster path to livable area |
| Interior conversion | Existing space inside the home converted to a separate unit | There is underused space, such as a basement or large room, with separate access possible |
What the state rules generally do
State law generally requires cities to review compliant ADU applications on a streamlined basis, and it limits some local requirements, such as certain parking and setback rules. Size limits, height limits, utility connections, fire requirements and design standards still apply and differ by city. We check the current rules for your parcel rather than relying on rules of thumb.
What the project involves
Feasibility
We look at the lot, setbacks, utilities, existing structures and what you want the ADU to be.
Design and engineering
Plans, structural design and the supporting documents your city requires.
Permits
Submittal, plan-check responses and approval.
Construction
Site work, foundation, framing, systems, finishes and final inspections.
Things to decide early
- Utility strategy: connect to existing water, sewer and power, or upgrade capacity.
- Heating and cooling choice for a small, efficient unit.
- Privacy and access: pathway, entrance placement and windows.
- Whether the unit will be rented, which affects layout and finishes.
- How the ADU relates to your existing landscaping, trees and easements.
ADUs and fire zones
Properties in the foothills of Burbank, Glendale, Pasadena and Altadena may be in fire-hazard zones with stricter building standards for exterior materials, vents and defensible space. These affect cost and design and are best addressed from the first sketch.