ADU Structural Design in California
ADU structural design coordinates the foundation, floor, wall, roof, and seismic system with the architectural plans and site conditions. We engineer attached and detached accessory dwelling units and provide the structural calculations and drawings for local permit review.
- Typical engineering timeline
- 2–4 weeks
- Permit required?
- Yes — before ADU construction
- What you receive
- Foundation, framing, and lateral design set
- Cost basis
- Free review; fixed proposal after scope
Timelines and fee basis are CMZStudio planning estimates based on industry experience. They are not City processing times, official fee schedules, or a project-specific proposal.
Is this your situation?
- Detached backyard ADUs
- Attached additions and garage conversions
- Second-story or over-garage units
- Architects and owners who need a coordinated structural set
What you receive
Every engagement ends in signed documents your contractor can build from and the city can approve.
- 01
Foundation design
We size slabs, footings, anchors, and hold-downs for the building and available site information.
- 02
Framing and lateral design
We engineer gravity framing, shear walls, diaphragms, and connections.
- 03
Permit documents
We coordinate structural calculations and drawings with the architectural package.
How the engineering is done
- 1
Review
Check the site, architectural plans, jurisdiction, and available soil information.
- 2
Coordinate
Resolve openings, roof form, utilities, and architectural constraints.
- 3
Engineer
Design an efficient foundation, framing, and seismic load path.
- 4
Permit
Deliver the structural package and support structural plan-check responses.
Lei Zheng
Founder & Principal Engineer, CMZStudio
California Professional Engineer
Licensed engineering from first calculation through plan check.
Lei Zheng has held a California Civil Engineer license since 2006. At CMZStudio, he reviews structural decisions, prepares and stamps engineering documents, and supports responses through city plan check.
Official California DCA record
C-69809
- License holder
- Lei Zheng
- License type
- Civil Engineer
- Issued
- March 17, 2006
Status verified July 23, 2026
- California-licensed
- 20 years
- Official DCA record
- C-69809
Direct answers before you call
The permit jurisdiction and site conditions control the final scope. We confirm both during the free initial review.
See the engineering in context
Verify the requirements
These California sources support the licensing, code, and compliance information on this page.
Request a free structural review
Prefer to talk? +1 510-277-7700 · Mon–Fri · 9:00–18:00