Lamorinda hills
ADU Builders in Orinda, CA
In Orinda the lot usually decides the ADU. Steep grades, oaks and mapped fire hazard zones shape where a unit can go and how it must be built. County pre-approved (PADU) vendor plans are available, and Orinda is in the SD7 ADU Accelerator (up to $15,000).
Orinda essentials
What applies in Orinda as of October 2026
| Item | Orinda | Source |
|---|---|---|
| Building permits | Contra Costa County building inspection | County |
| Pre-approved plans | County PADU vendor plans; site-specific review still required | County |
| Rebate | SD7 ADU Accelerator, up to $15,000 | SD7 page |
| Fire zones | Mapped Fire Hazard Severity Zones require Chapter 7A wildfire-resistant construction | CAL FIRE |
| City ADU info | City of Orinda ADU page | City |
Steep lots
Slope, fire and access
- Foundations: stepped footings, piers or retaining walls are common; budget geotechnical and structural engineering.
- Fire-resistant construction: ignition-resistant siding, vents, decking and roofing under Chapter 7A in mapped zones.
- Prefab access: narrow, winding streets and tree canopies can block crane placement; confirm before choosing prefab (prefab ADUs).
- Sewer route: downhill runs to the house lateral are easier; uphill ADUs may need a pump.
- Conversions: an existing garage avoids most grading and is often the simplest Orinda ADU.
Moraga shares the County PADU program and SD7 eligibility. Rules & permits → · Cost →
FAQ
Orinda ADU questions
Can I use pre-approved ADU plans in Orinda?
Yes. Orinda is served by Contra Costa County building inspection, so County PADU vendor plans can be used. You still need planning and building permits, a foundation design and site review.
Is Orinda in the SD7 ADU rebate program?
Yes. Orinda is listed in the SD7 ADU Accelerator, which offers up to $15,000 per qualifying ADU while each city's allocation lasts.
Can a prefab ADU be installed on a steep Orinda lot?
Sometimes. It depends on whether a truck and crane can reach the pad past narrow streets, trees and power lines. Get an access check before choosing a model.
Next step
Plan your Orinda ADU
Share your lot and goals. A local ADU builder can review feasibility and give you a quote.