ADU Structural Engineering in Orange County — Permit-Ready Plans from a Licensed PE
PE-stamped structural plans for garage conversions, detached ADUs, attached ADUs, and JADUs. Foundation design, framing plans, lateral system calculations, and full plan check support — from a licensed PE who stays on your project start to finish.
Structural Engineering for Every ADU Type
California allows multiple unit types on single-family lots. Each has distinct structural requirements. Affinity engineers all of them.
Garage conversion
Converting an existing garage into habitable space. Requires slab evaluation, wall framing assessment, lateral compliance, and new load path design.
Existing slab evaluation
Framing retrofit design
5–10 business days
Detached ADU
New freestanding structure. Requires complete structural design — new slab, framing, lateral system, and all connections from foundation through roof.
New slab-on-grade
Full lateral system
2–3 weeks
Attached ADU / JADU
Converting existing space or adding an attached unit. Scope depends on modifications to existing load paths and connection to the primary structure.
Existing structure analysis
Connection details
5–10 business days
Converting an existing garage?
Garage-to-ADU conversions have a different structural scope than new construction. Existing slab evaluation, framing modifications, lateral system upgrades, and seismic compliance — all engineered for your city's plan check standards.
Every ADU Package Includes
Structural calculations
Seismic (ASCE 7), wind, and gravity load analysis. Foundation design, beam sizing, connection forces — current California Building Code.
PE-stamped drawings
Foundation plan, framing plan, shear wall layout, connection details — detailed enough that your GC builds from them without field questions.
Jurisdiction review + PE stamp
Drawings reviewed against your city's plan check triggers before submission. PE stamp and signature — P.E. #82726, California.
Corrections + construction support
Plan check corrections responded to within 48 hours. Direct PE access during construction for RFIs, inspections, and field questions.
"From the first consultation visit to the delivery of final plans, Daniel went above and beyond to help us."
— Yelp Review, Orange County, CA
From First Call to Approved Permit
Scope call
Call or text (714) 215-7413, or submit the quote form. We review your ADU project and send a written scope with a firm fee within 24 hours.
Same-day response. No obligation.
Document collection
Architectural plans, site survey, existing conditions gathered. GC coordination if applicable.
1–2 business days after deposit.
Structural design
Foundation, framing, lateral system, connections — all to ASCE 7, NDS, ACI 318. Reviewed against your city's plan check standards.
Garage: 5–10 days. Detached ADU: 2–3 weeks.
Delivery, stamp, and support
PE-stamped drawings delivered. Plan check corrections handled within 48 hours. Your PE stays available through construction for every RFI and inspection.
Support through project close.
Frequently Asked Questions
Do I need a structural engineer for an ADU?
What does a structural engineer do for an ADU?
How long does it take to get ADU structural plans?
Can you help if my garage slab isn't adequate?
Do you work with my city's building department?
Structural engineer vs architect — who do I need?
Other Structural Engineering Services
Garage conversion
Dedicated structural design for garage-to-ADU conversions. Slab evaluation, framing retrofit, shear wall compliance.
Room additions
Structural plans for additions, second stories, and open-concept remodels. Beam sizing and load path design.
Inspections & letters
PE-stamped inspection letters for real estate, insurance, and permit compliance. Reports in 3–5 business days.