Engineering Services
Structural Engineering Services in Orange County & LA County
Every project gets direct PE attention, drawings your team can build from, and construction-phase support as standard.
ADU & garage conversion
Foundation, framing, and lateral system design for attached, detached, and garage-conversion ADUs.
Room additions & remodels
Structural design for additions, second stories, and open-concept remodels. Beam sizing and load path design.
Load-bearing wall removal
Beam and column sizing for safe wall removal. PE-stamped plans for open floor plan conversions.
Inspections & PE letters
PE-stamped letters for real estate, insurance, and permit compliance. Clear findings and recommendations.
Commercial & TI
Structural engineering for tenant improvements, seismic anchorage, equipment platforms, and code compliance.
Seismic retrofit
Retrofit design, foundation bolting, shear walls. Rooftop analysis.
Complete Plan Sets
Architecture, structural engineering, and MEP coordinated under one PE's oversight. One engagement, one set of drawings, one point of contact. No separate consultants to manage.
Architectural design — floor plans, elevations, sections, PE-stamped structural calculations and drawings, MEP engineering — mechanical, electrical, plumbing, All disciplines coordinated before submission, Plan check corrections + construction support
Who we work with
How we make your project easier.
For homeowners
You don’t need to understand structural engineering — that’s our job. You need clear answers, a firm timeline, and someone who picks up the phone when you have a question.
Plain-language guidance through the permit process
Written scope and firm quote before any work starts
Same-day response on every call, text, and email
For contractors & architects
Your structural engineer should make your job easier, not harder. Drawings detailed enough that your framing crew doesn’t call with questions. RFI responses the same day they’re sent.
Construction-ready plan sets — no field guesswork
Direct PE line for RFIs and inspection-day questions
Available through construction — not just through stamp
Three phases. Full PE oversight. Zero surprises.
From the first call to the final inspection, every project is led by a licensed PE with direct access throughout.
Scope and quote
Submit the form. Tell us the project type, address, and timeline. You'll have a written scope and firm fee within 24 hours.
Engineering and stamp
PE-stamped structural drawings and calculations — seismic, wind, and gravity as required. Every set is reviewed against your city's plan check standards before submission.
Construction support
When your permit is approved and construction begins, your PE stays directly available. RFIs, field questions, inspector issues — all handled same business day.
What Homeowners and Contractors Say
"He was reasonably priced, knowledgeable, committed and always available."
— Google Review, Irvine, CA
"From the first consultation visit to the delivery of final plans, Daniel went above and beyond to help us.""
— Yelp Review, Orange County, CA
"Daniel's patience and attention to detail were exceptional in designing condo units for my multi-zoned property.""
— Yelp Review, Orange County, CA
Daniel De Witte, P.E.
Every project at Affinity Design Group is led by Daniel De Witte, P.E. (#82726) — a California licensed Professional Engineer with jurisdiction-specific knowledge across Orange County and Los Angeles County.
When you call, your engineer answers. When your inspector has a question, your engineer responds. Need architecture or MEP alongside structural? We handle that too — one firm, one coordinated plan set.
Serving Orange County & Southeast Los Angeles County
Jurisdiction-specific plan check knowledge for building departments across both counties.